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[hreg] Assistance RESPONSE

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  • Bashir Syed
    ... From: Bashir Syed To: hreg@yahoogroups.com Sent: Friday, September 02, 2005 9:09 PM Subject: Re: [hreg] Assistance John: Here is how one computes the
    Message 1 of 11 , Sep 2, 2005
      Corrected version:
      ----- Original Message -----
      Sent: Friday, September 02, 2005 9:09 PM
      Subject: Re: [hreg] Assistance

      John:
      Here is how one computes the payoff time for the system
      Life expectancy of the PV System (less the cost of changing  and maintaining the storage batteries): 
                     Mono-Crystalline & Poly-crystalline  ~ 25 years
                     Thin Film or Amorphous PV ~ 10 years
      Data Required for Computing Cost benefits:
          1. Insolation data (amount of sunlight in kWh/sq. meter) obtained from maps prepared by National Renewable Energy Laboratory ( www.nrel.gov or check with Google
      NREL site provides the approximate daily insolation (amount of sunlight) in kWh/sq.meter that falls on a south-facing surface for an average day.
      For example, for Houston, TX  this value from NREL maps Insolation - ln. (Hstn)  = 5 kWh/sq.meter
      [The value in Alaska ~ 3 kWh/sq.meter.  The value for  Southern Arizona ~ 7 kWh/sq. meter] from U.S. Map.
       
          2. Energy provided by Sun/ sq. meter = E(sun) = 1 kW/sq.m
       
          3. The average Efficiency of the Solar PV Panels, eff (PV)  ~ 12% (for our calclculations)
       
          4. Yearly consumption of energy from Utility Bill  = E/year  in kWh/year
                 Let us assume for example: E/month = 450 kWh/month (average);   or   E/year = 5400 kWh/year
                 This information can be used to compute average energy usage per day = 
                 Average Energy Consumption /day= <E/day> = [E(consumed/yr)/ 365 days/yr] = <E/day> ~ 15 kWh/day
                 (Note: Average over a year period provides better estimates]
       
      Computations:
      (a) Area of PV array (in sq. meters) needed to provide this much Energy/day =
                     [ (<E/day in kWh/day>) / [(Insolation in kW/sq.m ) X (eff. of PV)] = [15 kWh/day] / [(5 kWh/sq.m/day) X (eff. 012)]  = 25 sq. meter 
       
      (b) Output (peak) of selected PV Array:
                     [ E(sun) X (eff.of PV) X (Computed area of PV array)] = [ (1 kW/sq.m) X (0.12) X (25 sq. m)] = 3.0 kW (Peak)  
       
      (c) Number years to payoff the cost of PV System:  N (For our Hypothetical example)
                     Let us say, Total System cost  = C(syst)  for example $18,000
                      Average, Yearly Utility Bill         =  C(util)    for our example is #3,000/year  (which by the way will always be increasing every year)
                      N = [C(syst)] / [C(util) = [ $18,000] / [$3,000] = 6 years
                     i.e. It will take ~ 6 years to pay off the Cost of PV System (not considering the cost of replacing batteries)
      Therefore, one can recover the cost this system in our example in about 6 years, and the only extra cost will be to replace and maintain the batteries.
      For next 19 years the electricity will be literally FREE (since there is no fuel cost at all).
      I checked my utility bill and found that half the charges billed to me were for Fuel - a charge which which will keep on increasing.  
       
      I hope the above example clarifies the mystries of PV Systems, and the Cost savings in the long run over 25 year period - the life expectancy of Mono/Poly -Crystalline Silicon PV Systems. 
       
       
      Bashir A. Syed  
       
       
       
       
      ----- Original Message -----
      Sent: Friday, September 02, 2005 2:40 PM
      Subject: Re: [hreg] Assistance

      Jane, we can help you but will need more deatails to give payback. perhaps
      we can do this offline.

      send info or call me

      thanks
      jmiggins@...



      John Miggins
      Harvest Solar & Wind Power
      "renewable solutions to everyday needs"
      www.harvest-energy.com
      Phone/Fax 918-743-2299
      Cell: 918-521-6223

      ----- Original Message -----
      From: "Jane Edgar" <jedgar@...>
      To: <hreg@yahoogroups.com>
      Sent: Friday, September 02, 2005 12:30 PM
      Subject: [hreg] Assistance


      > Can anyone give me factual calculations on the use of photovoltaics  i.e.
      > cost benefits and payback period.
      >
      > I need to convince my company that we could actually run our offices on
      > solar.  We have so many covered walk ways that we could fit arrays of
      > modules to them.
      >
      > Best regards Jane
      >
      >
      >
      >
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
      >
      >

    • Andrew McCalla
      All, There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using
      Message 2 of 11 , Sep 3, 2005

        All,

         

        There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.

         

        The method however, that has been presented in this thread, is most peculiar.

         

        First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn’t acceptable to simply de-rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.

         

        This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.  To be clear: it would not, at least not in Houston . 

         

        Secondly, and regarding the basis for the calculations we have seen: 

        It will be very hard to install to functionality a quality 3 kW system installed for $18K.  Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K).  Perhaps this includes environmental costs or other “intangibles”, which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis. 

         

        I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones.  However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people’s energy “needs”.

         

        See below for a more “real world” projection for what the 3 kW system in question might actually do in Houston :

         

        Station Identification

        City:

        Houston

        State:

        TX  

        Latitude:

        29.98° N

        Longitude:    

        95.37° W

        Elevation:

        33 m

        PV System Specifications

        DC Rating:

        3.0 kW

        DC to AC Derate Factor:

        0.770

        AC Rating:

        2.3 kW

        Array Type:

        Fixed Tilt  

        Array Tilt:

        30.0°

        Array Azimuth:

        180.0°

        Energy Specifications

        Cost of Electricity:    

        9.2 ¢/kWh

         

         

         

        Results


        Month

        Solar Radiation
        (kWh/m2/day)

        AC Energy
        (kWh)

        Energy Value (estimated)
        ($)

        3.68     

        252   

        23.18   

        4.12     

        251   

        23.09   

        4.82     

        321   

        29.53   

        4.98     

        315   

        28.98   

        5.24     

        335   

        30.82   

        5.53     

        337   

        31.00   

        5.43     

        338   

        31.10   

        5.44     

        342   

        31.46   

        5.40     

        332   

        30.54   

        10 

        5.19     

        334   

        30.73   

        11 

        4.33     

        277   

        25.48   

        12 

        3.34     

        226   

        20.79   

         

         

         

         

         

         

         

         

        Year 

        4.79     

        3660   

        336.72   

         

         

         

        And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:

         

         

        Station Identification

        City:

        Houston

        State:

        TX  

        Latitude:

        29.98° N

        Longitude:    

        95.37° W

        Elevation:

        33 m

        PV System Specifications

        DC Rating:

        4.5 kW

        DC to AC Derate Factor:

        0.770

        AC Rating:

        3.5 kW

        Array Type:

        Fixed Tilt  

        Array Tilt:

        30.0°

        Array Azimuth:

        180.0°

        Energy Specifications

        Cost of Electricity:    

        9.2 ¢/kWh

         

         

         

        Results


        Month

        Solar Radiation
        (kWh/m2/day)

        AC Energy
        (kWh)

        Energy Value (estimated)
        ($)

        3.68     

        377   

        34.68   

        4.12     

        376   

        34.59   

        4.82     

        481   

        44.25   

        4.98     

        472   

        43.42   

        5.24     

        502   

        46.18   

        5.53     

        505   

        46.46   

        5.43     

        508   

        46.74   

        5.44     

        514   

        47.29   

        5.40     

        498   

        45.82   

        10 

        5.19     

        500   

        46.00   

        11 

        4.33     

        416   

        38.27   

        12 

        3.34     

        339   

        31.19   

         

         

         

         

         

         

         

         

        Year 

        4.79     

        5489   

        504.99 

         

         

         

        Andrew H. McCalla

        Meridian Energy Systems

        2300 S. Lamar, Ste. 107

        Austin, TX   78704

         

        Voice: (512) 448-0055

        Fax:    (512) 448-0045

        www.meridiansolar.com

         

         

      • Robert Johnston
        Andrew, Bashir: If I put Bashir’s $6/W cost with Andrews estimate of 4.5kWh system for $505 worth of annual electrical energy, then that says the system
        Message 3 of 11 , Sep 3, 2005

          Andrew, Bashir:


          If I put Bashir’s $6/W cost with Andrews estimate of 4.5kWh system for $505 worth of annual electrical energy, then that says the system should cost on the order of $27,000 to install.  If it saves $505 in electrical energy costs, that is a 53 year payback, or twice the expected life of the equipment.  I haven’t made allowance for rising electricity costs, but neither have I factored in the finance costs of the system (or the opportunity cost of spending the $27k if one were to tie up that much cash instead of investing it elsewhere), so isn’t this reasonable for a very rough calculation?  If this is correct, then what Andrew is showing us is what I’ve always heard—that PV is not yet economically viable except for remote installations.  Am I missing something?

           

          Robert Johnston

           


          From: hreg@yahoogroups.com [mailto: hreg@yahoogroups.com ] On Behalf Of Andrew McCalla
          Sent: Saturday, September 03, 2005 7:15 AM
          To: hreg@yahoogroups.com
          Subject: RE: [hreg] Assistance RESPONSE

           

          All,

           

          There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.

           

          The method however, that has been presented in this thread, is most peculiar.

           

          First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn’t acceptable to simply de- rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.

           

          This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.  To be clear: it would not, at least not in Houston . 

           

          Secondly, and regarding the basis for the calculations we have seen: 

          It will be very hard to install to functionality a quality 3 kW system installed for $18K.  Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K).  Perhaps this includes environmental costs or other “intangibles”, which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis. 

           

          I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones.  However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people’s energy “needs”.

           

          See below for a more “real world” projection for what the 3 kW system in question might actually do in Houston :

           

          Station Identification

          City:

          Houston

          State:

          TX  

          Latitude:

          29.98° N

          Longitude:    

          95.37° W

          Elevation:

          33 m

          PV System Specifications

          DC Rating :

          3.0 kW

          DC to AC Derate Factor:

          0.770

          AC Rating :

          2.3 kW

          Array Type:

          Fixed Tilt  

          Array Tilt:

          30.0°

          Array Azimuth:

          180.0°

          Energy Specifications

          Cost of Electricity:    

          9.2 ¢/kWh

           

           

           

          Results


          Month

          Solar Radiation
          (kWh/m2/day)

          AC Energy
          (kWh)

          Energy Value (estimated)
          ($)

          3.68     

          252   

          23.18   

          4.12     

          251   

          23.09   

          4.82     

          321   

          29.53   

          4.98     

          315   

          28.98   

          5.24     

          335   

          30.82   

          5.53     

          337   

          31.00   

          5.43     

          338   

          31.10   

          5.44     

          342   

          31.46   

          5.40     

          332   

          30.54   

          10 

          5.19     

          334   

          30.73   

          11 

          4.33     

          277   

          25.48   

          12 

          3.34     

          226   

          20.79   

           

           

           

           

           

           

           

           

          Year 

          4.79     

          3660   

          336.72   

           

           

           

          And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:

           

           

          Station Identification

          City:

          Houston

          State:

          TX  

          Latitude:

          29.98° N

          Longitude:    

          95.37° W

          Elevation:

          33 m

          PV System Specifications

          DC Rating :

          4.5 kW

          DC to AC Derate Factor:

          0.770

          AC Rating :

          3.5 kW

          Array Type:

          Fixed Tilt  

          Array Tilt:

          30.0°

          Array Azimuth:

          180.0°

          Energy Specifications

          Cost of Electricity:    

          9.2 ¢/kWh

           

           

           

          Results


          Month

          Solar Radiation
          (kWh/m2/day)

          AC Energy
          (kWh)

          Energy Value (estimated)
          ($)

          3.68     

          377   

          34.68   

          4.12     

          376   

          34.59   

          4.82     

          481   

          44.25   

          4.98     

          472   

          43.42   

          5.24     

          502   

          46.18   

          5.53     

          505   

          46.46   

          5.43     

          508   

          46.74   

          5.44     

          514   

          47.29   

          5.40     

          498   

          45.82   

          10 

          5.19     

          500   

          46.00   

          11 

          4.33     

          416   

          38.27   

          12 

          3.34     

          339   

          31.19   

           

           

           

           

           

           

           

           

          Year 

          4.79     

          5489   

          504.99 

           

           

           

          Andrew H. McCalla

          Meridian Energy Systems

          2300 S. Lamar, Ste. 107

          Austin, TX   78704

           

          Voice: (512) 448-0055

          Fax:    (512) 448-0045

          www.meridiansolar.com

           

           

           

        • John Miggins
          Thanks for the help Bashir, your calculations helped me clarify the calcuation process and thanks for the clarification Andrew. I appreciate this thread as it
          Message 4 of 11 , Sep 3, 2005
            Thanks for the help Bashir, your calculations helped me clarify the calcuation process and thanks for the clarification Andrew.  I appreciate this thread as it goes to the heart of what we often encounter in the solar business.  People want to know how long it will take to pay for their system and  it often shows a long time, over 20 years.  I have struggled with this and asked Bashir for his method thinking that I had missed something.  What is true payback period and what is true cost of line power are legitimate questions.
             
            I do know that new panels are hot or produce up to 15% more than they are rated to allow for some loss in power over time.  a 150 watt panel will actually put out over 170 watts.  This should be figured into the equation but a dissipation of this effect will need to be included as well.
             
            Incentives are what is driving the market, california being one instance, as well as remote users who have little other choice.  For people in urban areas, the payback may be long but seeing what has happened in LA/MS it makes sense to have some solar capability for back-up to run your refrig, phone, some lights and fans in case power goes out.  This can be done for $5000 or less and will provide for some security and peace of mind.
             
            Payback goes out the window when the power is out.
            solar thermal makes sense right now, payback is less than 5 years.
             
             
             
             
             
            John Miggins
            Harvest Solar & Wind Power
            "renewable solutions to everyday needs"
            www.harvest-energy.com
            Phone/Fax 918-743-2299
            Cell: 918-521-6223
            ----- Original Message -----
            Sent: Saturday, September 03, 2005 7:15 AM
            Subject: RE: [hreg] Assistance RESPONSE

            All,

             

            There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.

             

            The method however, that has been presented in this thread, is most peculiar.

             

            First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn’t acceptable to simply de-rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.

             

            This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.  To be clear: it would not, at least not in Houston . 

             

            Secondly, and regarding the basis for the calculations we have seen: 

            It will be very hard to install to functionality a quality 3 kW system installed for $18K.  Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K).  Perhaps this includes environmental costs or other “intangibles”, which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis. 

             

            I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones.  However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people’s energy “needs”.

             

            See below for a more “real world” projection for what the 3 kW system in question might actually do in Houston :

             

            Station Identification

            City:

            Houston

            State:

            TX  

            Latitude:

            29.98° N

            Longitude:    

            95.37° W

            Elevation:

            33 m

            PV System Specifications

            DC Rating:

            3.0 kW

            DC to AC Derate Factor:

            0.770

            AC Rating:

            2.3 kW

            Array Type:

            Fixed Tilt  

            Array Tilt:

            30.0°

            Array Azimuth:

            180.0°

            Energy Specifications

            Cost of Electricity:    

            9.2 ¢/kWh

             

             

             

            Results


            Month

            Solar Radiation
            (kWh/m2/day)

            AC Energy
            (kWh)

            Energy Value (estimated)
            ($)

            3.68     

            252   

            23.18   

            4.12     

            251   

            23.09   

            4.82     

            321   

            29.53   

            4.98     

            315   

            28.98   

            5.24     

            335   

            30.82   

            5.53     

            337   

            31.00   

            5.43     

            338   

            31.10   

            5.44     

            342   

            31.46   

            5.40     

            332   

            30.54   

            10 

            5.19     

            334   

            30.73   

            11 

            4.33     

            277   

            25.48   

            12 

            3.34     

            226   

            20.79   

             

             

             

             

             

             

             

             

            Year 

            4.79     

            3660   

            336.72   

             

             

             

            And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:

             

             

            Station Identification

            City:

            Houston

            State:

            TX  

            Latitude:

            29.98° N

            Longitude:    

            95.37° W

            Elevation:

            33 m

            PV System Specifications

            DC Rating:

            4.5 kW

            DC to AC Derate Factor:

            0.770

            AC Rating:

            3.5 kW

            Array Type:

            Fixed Tilt  

            Array Tilt:

            30.0°

            Array Azimuth:

            180.0°

            Energy Specifications

            Cost of Electricity:    

            9.2 ¢/kWh

             

             

             

            Results


            Month

            Solar Radiation
            (kWh/m2/day)

            AC Energy
            (kWh)

            Energy Value (estimated)
            ($)

            3.68     

            377   

            34.68   

            4.12     

            376   

            34.59   

            4.82     

            481   

            44.25   

            4.98     

            472   

            43.42   

            5.24     

            502   

            46.18   

            5.53     

            505   


            (Message over 64 KB, truncated)

          • Andrew McCalla
            Robert, Bass boats aren’t economically feasible for 99% of their owners either, but they are selling them like hotcakes (no offense to any Bass fisherpeople
            Message 5 of 11 , Sep 3, 2005

              Robert,

               

              Bass boats aren’t economically feasible for 99% of their owners either, but they are selling them like hotcakes (no offense to any Bass fisherpeople out there, but there is a much cheaper way to get fish).

               

              I don’t think you are missing too much, except perhaps that most consumers of pv aren’t looking at the purchase of a system primarily as an investment such as they might stock, real estate, etc.…… and certainly not in this market of incredibly inexpensive utility costs.  Instead, it is a beneficial, fascinating device that is for some, a luxury item……. one that happens to have a payback.

               

              However, unlike other luxury items (luxury automobiles, hot tubs, big-screen TV’s, and bass boats) pv actually does have a payback, and actually does, from the minute it is exposed to sunlight and put to work, begin to offset the amount of energy required in its manufacture.

               

              I think Randy Udall captured the sentiment quite well in this article:

              http://www.solenergy.org/pdf/PV101/GridConnectedPV-Udall.pdf

               

              And for those of you wanting to get into the energy payback component a bit more deeply:

              http://www.homepower.com/files/pvpayback.pdf

               

               

              Andrew H. McCalla

              Meridian Energy Systems

              2300 S. Lamar, Ste. 107

              Austin, TX   78704

               

              Voice: (512) 448-0055

              Fax:    (512) 448-0045

              www.meridiansolar.com

               


              From: hreg@yahoogroups.com [mailto: hreg@yahoogroups.com ] On Behalf Of Robert Johnston
              Sent: Saturday, September 03, 2005 9:07 AM
              To: hreg@yahoogroups.com
              Subject: RE: [hreg] Assistance RESPONSE

               

              Andrew, Bashir:


              If I put Bashir’s $6/W cost with Andrews estimate of 4.5kWh system for $505 worth of annual electrical energy, then that says the system should cost on the order of $27,000 to install.  If it saves $505 in electrical energy costs, that is a 53 year payback, or twice the expected life of the equipment.  I haven’t made allowance for rising electricity costs, but neither have I factored in the finance costs of the system (or the opportunity cost of spending the $27k if one were to tie up that much cash instead of investing it elsewhere), so isn’t this reasonable for a very rough calculation?  If this is correct, then what Andrew is showing us is what I’ve always heard—that PV is not yet economically viable except for remote installations.  Am I missing something?

               

              Robert Johnston

               


              From: hreg@yahoogroups.com [mailto: hreg@yahoogroups.com ] On Behalf Of Andrew McCalla
              Sent: Saturday, September 03, 2005 7:15 AM
              To: hreg@yahoogroups.com
              Subject: RE: [hreg] Assistance RESPONSE

               

              All,

               

              There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.

               

              The method however, that has been presented in this thread, is most peculiar.

               

              First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn’t acceptable to simply de- rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.

               

              This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.  To be clear: it would not, at least not in Houston . 

               

              Secondly, and regarding the basis for the calculations we have seen: 

              It will be very hard to install to functionality a quality 3 kW system installed for $18K.  Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K).  Perhaps this includes environmental costs or other “intangibles”, which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis. 

               

              I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones.  However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people’s energy “needs”.

               

              See below for a more “real world” projection for what the 3 kW system in question might actually do in Houston :

               

              Station Identification

              City:

              Houston

              State:

              TX  

              Latitude:

              29.98° N

              Longitude:    

              95.37° W

              Elevation:

              33 m

              PV System Specifications

              DC Rating :

              3.0 kW

              DC to AC Derate Factor:

              0.770

              AC Rating :

              2.3 kW

              Array Type:

              Fixed Tilt  

              Array Tilt:

              30.0°

              Array Azimuth:

              180.0°

              Energy Specifications

              Cost of Electricity:    

              9.2 ¢/kWh

               

               

               

              Results


              Month

              Solar Radiation
              (kWh/m2/day)

              AC Energy
              (kWh)

              Energy Value (estimated)
              ($)

              3.68     

              252   

              23.18   

              4.12     

              251   

              23.09   

              4.82     

              321   

              29.53   

              4.98     

              315   

              28.98   

              5.24     

              335   

              30.82   

              5.53     

              337   

              31.00   

              5.43     

              338   

              31.10   

              5.44     

              342   

              31.46   

              5.40     

              332   

              30.54   

              10 

              5.19     

              334   

              30.73   

              11 

              4.33     

              277   

              25.48   

              12 

              3.34     

              226   

              20.79   

               

               

               

               

               

               

               

               

              Year 

              4.79     

              3660   

              336.72   

               

               

               

              And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:

               

               

              Station Identification

              City:

              Houston

              State:

              TX  

              Latitude:

              29.98° N

              Longitude:    

              95.37° W

              Elevation:

              33 m

              PV System Specifications

              DC Rating :

              4.5 kW

              DC to AC Derate Factor:

              0.770

              AC Rating :

              3.5 kW

              Array Type:

              Fixed Tilt  

              Array Tilt:

              30.0°

              Array Azimuth:

              180.0°

              Energy Specifications

              Cost of Electricity:    

              9.2 ¢/kWh

               

               

               

              Results


              Month

              Solar Radiation
              (kWh/m2/day)

              AC Energy
              (kWh)

              Energy Value (estimated)
              ($)

              3.68     

              377   

              34.68   

              4.12     

              376   

              34.59   

              4.82     

              481   

              44.25   

              4.98     

              472   

              43.42   

              5.24     

              502   

              46.18   

              5.53     

              505   

              46.46   

              5.43     

              508   

              46.74   

              5.44     

              514   

              47.29   

              5.40     

              498   

              45.82   

              10 

              5.19     

              500   

              46.00   

              11 

              4.33     

              416   

              38.27   

              12 

              3.34     

              339   

              31.19   

               

               

               

               

               

               

               

               

              Year 

              4.79     

              5489   

              504.99 

               

               

               

              Andrew H. McCalla

              Meridian Energy Systems

              2300 S. Lamar, Ste. 107

              Austin, TX   78704

               

            • SBT Designs
              Why don t we just stop kidding ourselves? The entire concept of payback from a solar power system is a dinosaur from the 1980s when the government,
              Message 6 of 11 , Sep 3, 2005
                Why don't we just stop kidding ourselves?  The entire concept of "payback" from a solar power system is a dinosaur from the 1980s when the government, academics and solar vendors alike were trying to justify to the American consumer (the most uneducated consumer in the world) why we should invest in solar.  At best this data is a weak marketing tool.
                 
                So called calculations of payback are little more than fiction because all renewable energy systems are subject to the behavior of weather.  We have been trying to predict the weather for thousands of years with less than accurate results.  Because you cannot tell me what the weather will be like tomorrow you also cannot tell me how much power a renewable energy power system will produce.  I can offer you any "calculations" you like for a solar power system for any location in the world.   Your calculations, my calculations and anyone else's calculations would be just as accurate as gazing into a crystal ball.  And your crystal ball works just as well as mine.  Most American consumers don't read and would not even understand payback calculations and estimates.  And let's not even bring up the topic of efficiencies.  When I am asked about efficiency that is always the first indication of a clueless consumer.  The next indication would be that consumer concerned about the "imbedded pollution" of the solar manufacturing process.  Give me a break.  These concerns and payback concerns are the concerns of a consumer who probably has no intention of investing in renewable energy - plain and simple.
                 
                The basic practical fact of investing in solar technology (or any renewable energy technology) is that a solar power system is an on site electric power generator capable of providing power if no utility power is available at all, capable of providing electricity in the event of utility failure and/or capable of producing distributed power that can be applied back to the grid at large.  The fuel for that generator is free, natural, nonpolluting sunshine.  If the American consumer cannot recognize the logic and practical nature of this basic fact (and they don't)  why waste time producing pages of nearly useless data that will end up in the trash can?  And what about the risk that some grubby lawyer might use that data against you in the future because your solar power system did not deliver as predicted by your payback estimates?
                 
                I'd rather spare the trees.
                 
                Steven Shepard
                SBT Designs
                25581 IH-10 West
                San Antonio, Texas 78257
                (210) 698-7109
                www.sbtdesigns.com
                ----- Original Message -----
                Sent: Saturday, September 03, 2005 7:15 AM
                Subject: RE: [hreg] Assistance RESPONSE

                All,

                 

                There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.

                 

                The method however, that has been presented in this thread, is most peculiar.

                 

                First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn’t acceptable to simply de-rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.

                 

                This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.  To be clear: it would not, at least not in Houston . 

                 

                Secondly, and regarding the basis for the calculations we have seen: 

                It will be very hard to install to functionality a quality 3 kW system installed for $18K.  Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K).  Perhaps this includes environmental costs or other “intangibles”, which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis. 

                 

                I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones.  However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people’s energy “needs”.

                 

                See below for a more “real world” projection for what the 3 kW system in question might actually do in Houston :

                 

                Station Identification

                City:

                Houston

                State:

                TX  

                Latitude:

                29.98° N

                Longitude:    

                95.37° W

                Elevation:

                33 m

                PV System Specifications

                DC Rating:

                3.0 kW

                DC to AC Derate Factor:

                0.770

                AC Rating:

                2.3 kW

                Array Type:

                Fixed Tilt  

                Array Tilt:

                30.0°

                Array Azimuth:

                180.0°

                Energy Specifications

                Cost of Electricity:    

                9.2 ¢/kWh

                 

                 

                 

                Results


                Month

                Solar Radiation
                (kWh/m2/day)

                AC Energy
                (kWh)

                Energy Value (estimated)
                ($)

                3.68     

                252   

                23.18   

                4.12     

                251   

                23.09   

                4.82     

                321   

                29.53   

                4.98     

                315   

                28.98   

                5.24     

                335   

                30.82   

                5.53     

                337   

                31.00   

                5.43     

                338   

                31.10   

                5.44     

                342   

                31.46   

                5.40     

                332   

                30.54   

                10 

                5.19     

                334   

                30.73   

                11 

                4.33     

                277   

                25.48   

                12 

                3.34     

                226   

                20.79   

                 

                 

                 

                 

                 

                 

                 

                 

                Year 

                4.79     

                3660   

                336.72   

                 

                 

                 

                And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:

                 

                 

                Station Identification

                City:

                Houston

                State:

                TX  

                Latitude:

                29.98° N

                Longitude:    

                95.37° W

                Elevation:

                33 m

                PV System Specifications

                DC Rating:

                4.5 kW

                DC to AC Derate Factor:

                0.770

                AC Rating:

                3.5 kW

                Array Type:

                Fixed Tilt  

                Array Tilt:

                30.0°

                Array Azimuth:

                180.0°

                Energy Specifications

                Cost of Electricity:    

                9.2 ¢/kWh

                 

                 

                 

                Results


                Month

                Solar Radiation
                (kWh/m2/day)

                AC Energy
                (kWh)

                Energy Value (estimated)
                ($)

                3.68     

                377   

                34.68   

                4.12     

                376   

                34.59   

                4.82     

                481   

                44.25   

                4.98     

                472   

                43.42   

                5.24     

                502   

                46.18   

              • J. P. Malone
                Thanks for the very direct answer. I agree with your assessment of our education as clueless consumers. I am guilty. I, see from your SBT Systems web site
                Message 7 of 11 , Sep 4, 2005

                  Thanks for the very direct answer. I agree with your assessment of our education as clueless consumers.  I am guilty.

                   

                  I, see from your SBT Systems web site that you specialize in installing solar systems.  So it must be a tough sell when you are basically selling either (1) a backup generator that may be seldom used, or (2) a luxury toy that only an elite few can truly afford without being ignorant about their personal capital allocation.

                   

                  I look forward to the day when a number of the products you sell will be efficient for average consumers & small businesses to use without the marketing hype you refer to in your email.

                   

                  Your web page states:

                  “Solar technology will make a positive impact on your bottom line reducing your overall electric utility costs.”

                  From what you say, I take it that this would be the case only in remote locations not serviced by the utility grid. 

                   

                  Thanks again for your straight forward response.  Your clear statement has made me less clueless than before about being a consumer of renewable energy.

                   

                  J. Patrick Malone

                   


                  From: hreg@yahoogroups.com [mailto: hreg@yahoogroups.com ] On Behalf Of SBT Designs
                  Sent: Saturday, September 03, 2005 10:32 PM
                  To: hreg@yahoogroups.com
                  Cc: Juan Gone; Joseph; Dominick A. Dina Sr.; Weldon Coldiron; Terry Hamilton; greenbuilding@...; 12VDC_Power@yahoogroups.com
                  Subject: Re: [hreg] Assistance RESPONSE

                   

                  Why don't we just stop kidding ourselves?  The entire concept of "payback" from a solar power system is a dinosaur from the 1980s when the government, academics and solar vendors alike were trying to justify to the American consumer (the most uneducated consumer in the world) why we should invest in solar.  At best this data is a weak marketing tool.

                   

                  So called calculations of payback are little more than fiction because all renewable energy systems are subject to the behavior of weather.  We have been trying to predict the weather for thousands of years with less than accurate results.  Because you cannot tell me what the weather will be like tomorrow you also cannot tell me how much power a renewable energy power system will produce.  I can offer you any "calculations" you like for a solar power system for any location in the world.   Your calculations, my calculations and anyone else's calculations would be just as accurate as gazing into a crystal ball.  And your crystal ball works just as well as mine.  Most American consumers don't read and would not even understand payback calculations and estimates.  And let's not even bring up the topic of efficiencies.  When I am asked about efficiency that is always the first indication of a clueless consumer.  The next indication would be that consumer concerned about the "imbedded pollution" of the solar manufacturing process.  Give me a break.  These concerns and payback concerns are the concerns of a consumer who probably has no intention of investing in renewable energy - plain and simple.

                   

                  The basic practical fact of investing in solar technology (or any renewable energy technology) is that a solar power system is an on site electric power generator capable of providing power if no utility power is available at all, capable of providing electricity in the event of utility failure and/or capable of producing distributed power that can be applied back to the grid at large.  The fuel for that generator is free, natural, nonpolluting sunshine.  If the American consumer cannot recognize the logic and practical nature of this basic fact (and they don't)  why waste time producing pages of nearly useless data that will end up in the trash can?  And what about the risk that some grubby lawyer might use that data against you in the future because your solar power system did not deliver as predicted by your payback estimates?

                   

                  I'd rather spare the trees.

                   

                  Steven Shepard
                  SBT Designs
                  25581 IH-10 West
                  San Antonio , Texas 78257
                  (210) 698-7109
                  www.sbtdesigns.com

                  ----- Original Message -----

                  Sent: Saturday, September 03, 2005 7:15 AM

                  Subject: RE: [hreg] Assistance RESPONSE

                   

                  All,

                   

                  There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.

                   

                  The method however, that has been presented in this thread, is most peculiar.

                   

                  First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn’t acceptable to simply de-rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.

                   

                  This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.  To be clear: it would not, at least not in Houston . 

                   

                  Secondly, and regarding the basis for the calculations we have seen: 

                  It will be very hard to install to functionality a quality 3 kW system installed for $18K.  Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K).  Perhaps this includes environmental costs or other “intangibles”, which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis. 

                   

                  I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones.  However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people’s energy “needs”.

                   

                  See below for a more “real world” projection for what the 3 kW system in question might actually do in Houston :

                   

                  Station Identification

                  City:

                  Houston

                  State:

                  TX  

                  Latitude:

                  29.98° N

                  Longitude:    

                  95.37° W

                  Elevation:

                  33 m

                  PV System Specifications

                  DC Rating:

                  3.0 kW

                  DC to AC Derate Factor:

                  0.770

                  AC Rating:

                  2.3 kW

                  Array Type:

                  Fixed Tilt  

                  Array Tilt:

                  30.0°

                  Array Azimuth:

                  180.0°

                  Energy Specifications

                  Cost of Electricity:    

                  9.2 ¢/kWh

                   

                   

                   

                  Results


                  Month

                  Solar Radiation
                  (kWh/m2/day)

                  AC Energy
                  (kWh)

                  Energy Value (estimated)
                  ($)

                  3.68     

                  252   

                  23.18   

                  4.12     

                  251   

                  23.09   

                  4.82     

                  321   

                  29.53   

                  4.98     

                  315   

                  28.98   

                  5.24     

                  335   

                  30.82   

                  5.53     

                  337   

                  31.00   

                  5.43     

                  338   

                  31.10   

                  5.44     

                  342   

                  31.46   

                  5.40     

                  332   

                  30.54   

                  10 

                  5.19     

                  334   

                  30.73   

                  11 

                  4.33     

                  277   

                  25.48   

                  12 

                  3.34     

                  226   

                  20.79   

                   

                   

                   

                   

                   

                   

                   

                   

                  Year 

                  4.79     

                  3660   

                  336.72   

                   

                   

                   

                  And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:

                   

                   

                  Station Identification

                  City:

                  Houston

                  State:

                  TX  

                  Latitude:

                  29.98° N

                  Longitude:    

                  95.37° W

                  Elevation:

                  33 m

                  PV System Specifications

                  DC Rating:

                  4.5 kW

                  DC to AC Derate Factor:

                  0.770

                  AC Rating:

                  3.5 kW

                  Array Type:

                  Fixed Tilt  

                  Array Tilt:

                  30.0°

                  Array Azimuth:

                  180.0°

                  Energy Specifications

                  Cost of Electricity:    

                  9.2 ¢/kWh

                   

                   

                   

                  Results


                  Month

                  Solar Radiation
                  (kWh/m2/day)

                  AC Energy
                  (kWh)

                  Energy Value (estimated)
                  ($)

                  3.68     

                  377   

                  34.68   

                  4.12     

                  376   

                  34.59   

                  4.82     

                  481   

                  44.25   

                  4.98     

                  472   

                  43.42   

                  5.24     

                  502   

                  46.18   

                  5.53     

                  505   

                  46.46   

                  5.43     

                  508   

                  46.74   

                  5.44     


                  (Message over 64 KB, truncated)
                • Robert Johnston
                  I keep hearing about solar as an insurance policy for power failures. I think a generator would be more reliable. Living on the Gulf Coast (not San Antonio),
                  Message 8 of 11 , Sep 4, 2005

                    I keep hearing about solar as an insurance policy for power failures.  I think a generator would be more reliable.  Living on the Gulf Coast (not San Antonio), I have seen what even Cat I storm winds can do. I think the chances of any PV panels on or around my home surviving a hurricane are slim.  If the wind didn’t directly send the panels flying, it would smash them with windblown debri, or drop a tree on them.  And I’d hate to think what flooding would do to electronics.

                     

                    As an insurance policy against “brownouts” such as California experienced a couple years ago, I think it makes more sense.  But not for hurricane insurance.

                     

                    Robert Johnston

                     

                     


                    From: hreg@yahoogroups.com [mailto:hreg@yahoogroups.com] On Behalf Of SBT Designs
                    Sent: Saturday, September 03, 2005 10:32 PM
                    To: hreg@yahoogroups.com
                    Cc: Juan Gone; Joseph; Dominick A. Dina Sr.; Weldon Coldiron; Terry Hamilton; greenbuilding@...; 12VDC_Power@yahoogroups.com
                    Subject: Re: [hreg] Assistance RESPONSE

                     

                    Why don't we just stop kidding ourselves?  The entire concept of "payback" from a solar power system is a dinosaur from the 1980s when the government, academics and solar vendors alike were trying to justify to the American consumer (the most uneducated consumer in the world) why we should invest in solar.  At best this data is a weak marketing tool.

                     

                    So called calculations of payback are little more than fiction because all renewable energy systems are subject to the behavior of weather.  We have been trying to predict the weather for thousands of years with less than accurate results.  Because you cannot tell me what the weather will be like tomorrow you also cannot tell me how much power a renewable energy power system will produce.  I can offer you any "calculations" you like for a solar power system for any location in the world.   Your calculations, my calculations and anyone else's calculations would be just as accurate as gazing into a crystal ball.  And your crystal ball works just as well as mine.  Most American consumers don't read and would not even understand payback calculations and estimates.  And let's not even bring up the topic of efficiencies.  When I am asked about efficiency that is always the first indication of a clueless consumer.  The next indication would be that consumer concerned about the "imbedded pollution" of the solar manufacturing process.  Give me a break.  These concerns and payback concerns are the concerns of a consumer who probably has no intention of investing in renewable energy - plain and simple.

                     

                    The basic practical fact of investing in solar technology (or any renewable energy technology) is that a solar power system is an on site electric power generator capable of providing power if no utility power is available at all, capable of providing electricity in the event of utility failure and/or capable of producing distributed power that can be applied back to the grid at large.  The fuel for that generator is free, natural, nonpolluting sunshine.  If the American consumer cannot recognize the logic and practical nature of this basic fact (and they don't)  why waste time producing pages of nearly useless data that will end up in the trash can?  And what about the risk that some grubby lawyer might use that data against you in the future because your solar power system did not deliver as predicted by your payback estimates?

                     

                    I'd rather spare the trees.

                     

                    Steven Shepard
                    SBT Designs
                    25581 IH-10 West
                    San Antonio , Texas 78257
                    (210) 698-7109
                    www.sbtdesigns.com

                    ----- Original Message -----

                    Sent: Saturday, September 03, 2005 7:15 AM

                    Subject: RE: [hreg] Assistance RESPONSE

                     

                    All,

                     

                    There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.

                     

                    The method however, that has been presented in this thread, is most peculiar.

                     

                    First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn’t acceptable to simply de- rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.

                     

                    This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.  To be clear: it would not, at least not in Houston . 

                     

                    Secondly, and regarding the basis for the calculations we have seen: 

                    It will be very hard to install to functionality a quality 3 kW system installed for $18K.  Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K).  Perhaps this includes environmental costs or other “intangibles”, which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis. 

                     

                    I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones.  However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people’s energy “needs”.

                     

                    See below for a more “real world” projection for what the 3 kW system in question might actually do in Houston :

                     

                    Station Identification

                    City:

                    Houston

                    State:

                    TX  

                    Latitude:

                    29.98° N

                    Longitude:    

                    95.37° W

                    Elevation:

                    33 m

                    PV System Specifications

                    DC Rating :

                    3.0 kW

                    DC to AC Derate Factor:

                    0.770

                    AC Rating :

                    2.3 kW

                    Array Type:

                    Fixed Tilt  

                    Array Tilt:

                    30.0°

                    Array Azimuth:

                    180.0°

                    Energy Specifications

                    Cost of Electricity:    

                    9.2 ¢/kWh

                     

                     

                     

                    Results


                    Month

                    Solar Radiation
                    (kWh/m2/day)

                    AC Energy
                    (kWh)

                    Energy Value (estimated)
                    ($)

                    3.68     

                    252   

                    23.18   

                    4.12     

                    251   

                    23.09   

                    4.82     

                    321   

                    29.53   

                    4.98     

                    315   

                    28.98   

                    5.24     

                    335   

                    30.82   

                    5.53     

                    337   

                    31.00   

                    5.43     

                    338   

                    31.10   

                    5.44     

                    342   

                    31.46   

                    5.40     

                    332   

                    30.54   

                    10 

                    5.19     

                    334   

                    30.73   

                    11 

                    4.33     

                    277   

                    25.48   

                    12 

                    3.34     

                    226   

                    20.79   

                     

                     

                     

                     

                     

                     

                     

                     

                    Year 

                    4.79     

                    3660   

                    336.72   

                     

                     

                     

                    And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:

                     

                     

                    Station Identification

                    City:

                    Houston

                    State:

                    TX  

                    Latitude:

                    29.98° N

                    Longitude:    

                    95.37° W

                    Elevation:

                    33 m

                    PV System Specifications

                    DC Rating :

                    4.5 kW

                    DC to AC Derate Factor:

                    0.770

                    AC Rating :

                    3.5 kW

                    Array Type:

                    Fixed Tilt  

                    Array Tilt:

                    30.0°

                    Array Azimuth:

                    180.0°

                    Energy Specifications

                    Cost of Electricity:    

                    9.2 ¢/kWh

                     

                     

                     

                    Results


                    Month

                    Solar Radiation
                    (kWh/m2/day)

                    AC Energy
                    (kWh)

                    Energy Value (estimated)
                    ($)

                    3.68     

                    377   

                    34.68   

                    4.12     

                    376   

                    34.59   

                    4.82     

                    481   

                    44.25   

                    4.98     

                    472   

                    43.42   

                    5.24     

                    502   

                    46.18   

                    5.53     

                    505   

                    46.46   

                    5.43     

                    508   

                    46.74   

                    5.44     

                    514   

                    47.29   

                    5.40     

                    498   

                    45.82   

                    10 

                    5.19     

                    500   

                    46.00   

                    11 

                    4.33     

                    416   

                    38.27   

                    12 

                    3.34     

                    339   

                    31.19   

                     

                     

                     

                     

                     

                     

                     

                     

                    Year 

                    4.79     

                    5489   

                    504.99 

                     

                     

                     

                    Andrew H. McCalla

                    Meridian Energy Systems

                    2300 S. Lamar, Ste. 107

                    Austin, TX   78704

                     

                    Voice: (512) 448-0055

                    Fax:    (512) 448-0045

                    www.meridiansolar.com

                  • John Miggins
                    Steve, I respectfully disagree on several points. You cannot lump all comsumers into one group- there are large numbers of highly educated literate consumers
                    Message 9 of 11 , Sep 4, 2005
                      Steve, I respectfully disagree on several points.
                       
                      You cannot lump all comsumers into one group- there are large numbers of highly educated literate consumers who have questions about solar and renewable energy products and it is our job to help educate them as to the benefit of our products.  Payback is one area that need to be explained and can be predicted very reliably. You can do alot to save energy without spending anything on solar panels. conservation, house design, and several other techniques are the first thing that should be done before investing in generation capacity.
                       
                      Weather, although not predictable, is predictable year over year within a small degree of error thanks to hundreds of years of weather data, we know generally how much solar irraditation will hit a specific area on a yearly basis.  True this can change but it will not change that much over time quickly.  You cannot agrue that you don't know that Alaska will be colder than Houston next winter, this is just common sense and geometry.
                       
                      We have found an increased interest in all forms or renewable energy and are happy to provide case studies, calculations and other "data" from very reliable sources to help people make informed decisions.  Solar panels can be mounted in such as way as to survive hurricane winds although flying debris may be a problem.  Also in a disaster a generator may be more robust and powerful, but you must have fuel for this, a luxury that may not be available.  We get fuel from the sky every day for free.
                       
                      Man's ability to survive and harness nature through the use of our biggest tool, our brain, is the reason we don't live in caves anymore. 
                       
                      The future of renewable energy is bright, I like to see the glass half full and actively try to fill it up the rest of the way.  Just my personal approach.  
                       
                       
                      John Miggins
                      Harvest Solar & Wind Power
                      "renewable solutions to everyday needs"
                      www.harvest-energy.com
                      Phone/Fax 918-743-2299
                      Cell: 918-521-6223
                      ----- Original Message -----
                      Sent: Saturday, September 03, 2005 10:32 PM
                      Subject: Re: [hreg] Assistance RESPONSE

                      Why don't we just stop kidding ourselves?  The entire concept of "payback" from a solar power system is a dinosaur from the 1980s when the government, academics and solar vendors alike were trying to justify to the American consumer (the most uneducated consumer in the world) why we should invest in solar.  At best this data is a weak marketing tool.
                       
                      So called calculations of payback are little more than fiction because all renewable energy systems are subject to the behavior of weather.  We have been trying to predict the weather for thousands of years with less than accurate results.  Because you cannot tell me what the weather will be like tomorrow you also cannot tell me how much power a renewable energy power system will produce.  I can offer you any "calculations" you like for a solar power system for any location in the world.   Your calculations, my calculations and anyone else's calculations would be just as accurate as gazing into a crystal ball.  And your crystal ball works just as well as mine.  Most American consumers don't read and would not even understand payback calculations and estimates.  And let's not even bring up the topic of efficiencies.  When I am asked about efficiency that is always the first indication of a clueless consumer.  The next indication would be that consumer concerned about the "imbedded pollution" of the solar manufacturing process.  Give me a break.  These concerns and payback concerns are the concerns of a consumer who probably has no intention of investing in renewable energy - plain and simple.
                       
                      The basic practical fact of investing in solar technology (or any renewable energy technology) is that a solar power system is an on site electric power generator capable of providing power if no utility power is available at all, capable of providing electricity in the event of utility failure and/or capable of producing distributed power that can be applied back to the grid at large.  The fuel for that generator is free, natural, nonpolluting sunshine.  If the American consumer cannot recognize the logic and practical nature of this basic fact (and they don't)  why waste time producing pages of nearly useless data that will end up in the trash can?  And what about the risk that some grubby lawyer might use that data against you in the future because your solar power system did not deliver as predicted by your payback estimates?
                       
                      I'd rather spare the trees.
                       
                      Steven Shepard
                      SBT Designs
                      25581 IH-10 West
                      San Antonio, Texas 78257
                      (210) 698-7109
                      www.sbtdesigns.com
                      ----- Original Message -----
                      Sent: Saturday, September 03, 2005 7:15 AM
                      Subject: RE: [hreg] Assistance RESPONSE

                      All,

                       

                      There are many ways of calculating the “payback” of a pv system………some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.

                       

                      The method however, that has been presented in this thread, is most peculiar.

                       

                      First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn’t acceptable to simply de-rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.

                       

                      This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.  To be clear: it would not, at least not in Houston . 

                       

                      Secondly, and regarding the basis for the calculations we have seen: 

                      It will be very hard to install to functionality a quality 3 kW system installed for $18K.  Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K).  Perhaps this includes environmental costs or other “intangibles”, which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis. 

                       

                      I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones.  However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people’s energy “needs”.

                       

                      See below for a more “real world” projection for what the 3 kW system in question might actually do in Houston :

                       

                      Station Identification

                      City:

                      Houston

                      State:

                      TX  

                      Latitude:

                      29.98° N

                      Longitude:    

                      95.37° W

                      Elevation:

                      33 m

                      PV System Specifications

                      DC Rating:

                      3.0 kW

                      DC to AC Derate Factor:

                      0.770

                      AC Rating:

                      2.3 kW

                      Array Type:

                      Fixed Tilt  

                      Array Tilt:

                      30.0°

                      Array Azimuth:

                      180.0°

                      Energy Specifications

                      Cost of Electricity:    

                      9.2 ¢/kWh

                       

                       

                       

                      Results


                      Month

                      Solar Radiation
                      (kWh/m2/day)

                      AC Energy
                      (kWh)

                      Energy Value (estimated)
                      ($)

                      3.68     

                      252   

                      23.18   

                      4.12     

                      251   

                      23.09   

                      4.82     

                      321   

                      29.53   

                      4.98     

                      315   

                      28.98   

                      5.24     

                      335   

                      30.82   

                      5.53     

                      337   

                      31.00   

                      5.43     

                      338   

                      31.10   

                      5.44     

                      342   

                      31.46   

                      5.40     

                      332   

                      30.54   

                      10 

                      5.19     

                      334   

                      30.73   

                      11 

                      4.33     

                      277   

                      25.48   

                      12 

                      3.34     

                      226   

                      20.79   

                       

                       

                       

                       

                       

                       

                       

                       

                      Year 

                      4.79     

                      3660   

                      336.72   

                       

                       

                       

                      And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:

                       

                       

                      Station Identification

                      City:

                      Houston

                      State:

                      TX  

                      Latitude:

                      29.98° N

                      Longitude:    

                      95.37° W

                      Elevation:

                      33 m

                      PV System Specifications

                      DC Rating:

                      4.5 kW

                      DC to AC Derate Factor:

                      0.770

                      AC Rating:

                      3.5 kW

                      Array Type:

                      Fixed Tilt  

                      Array Tilt:

                      30.0°

                      Array Azimuth:

                      180.0°

                      Energy Specifications

                      Cost of Electricity:    

                      9.2 ¢/kWh

                       

                       

                       

                      Results


                      Month

                      Solar Radiation
                      (kWh/m2/day)

                      AC Energy
                      (kWh)

                      Energy Value (estimated)
                      ($)



                      (Message over 64 KB, truncated)

                    • Richard D. Kelley
                      Perhaps this will help! Solar and Wind-Powered Energy Systems Exemption Last DSIRE Review: 08/12/2004 Incentive Type: Property Tax Exemption Eligible
                      Message 10 of 11 , Sep 9, 2005
                        Perhaps this will help!

                        Solar and Wind-Powered Energy Systems Exemption
                        Last DSIRE Review: 08/12/2004
                        Incentive Type: Property Tax Exemption
                        Eligible Renewable/Other Technologies: Passive Solar Space Heat, Solar Water Heat, Solar Space Heat, Photovoltaics, Wind, Biomass, Anaerobic Digestion
                        Applicable Sectors: Residential
                        Amount: 100%
                        Max. Limit: None
                        Authority 1: Texas Statutes § 11.27
                        Date Enacted: 1981


                        [NL]Summary:
                        The Texas property tax code allows an exemption of the amount of the appraised property value that arises from the installation or construction of a solar or wind-powered energy device that is primarily for the production and distribution of energy for on-site use. [NL][NL]"Solar energy device" means an apparatus designed or adapted to convert the radiant energy from the sun, including energy imparted to plants through photosynthesis employing the bioconversion processes of anaerobic digestion, gasification, pyrolysis, or fermentation, but not including direct combustion, into thermal, mechanical, or electrical energy; to store the converted energy, either in the form to which originally converted or another form; or to distribute radiant solar energy or the energy to which the radiant solar energy is converted. [NL][NL]"Wind-powered energy device" means an apparatus designed or adapted to convert the energy available in the wind into thermal, mechanical, or electrical energy; to store the converted energy, either in the form to which originally converted or another form; or to distribute the converted energy.


                        Contact:
                        Pam Groce[NL]Comptroller of Public Accounts[NL]State Energy Conservation Office[NL]111 East 17th Street, Room 1114[NL]Austin, TX 78774[NL]Phone: (512) 463-1889 [NL]Fax: (512) 475-2569[NL]E-Mail: pam.groce@...[NL]Web site: http://www.seco.cpa.state.tx.us[NL]

                        TEXAS STATUTES
                        TITLE 1. PROPERTY TAX CODE
                        SUBTITLE C. TAXABLE PROPERTY AND EXEMPTIONS
                        CHAPTER 11. TAXABLE PROPERTY AND EXEMPTIONS
                        SUBCHAPTER A. TAXABLE PROPERTY
                        § 11.27. Solar and Wind-Powered Energy Devices.
                        (a) A person is entitled to an exemption from taxation of the amount of appraised value of his property that arises from the installation or construction of a solar or wind-powered energy device that is primarily for production and distribution of energy for on-site use.
                        (b) The comptroller, with the assistance of the Texas Energy and Natural Resources Advisory Council, or its successor, shall develop guidelines to assist local officials in the administration of this section.
                        (c) In this section:
                        (1) "Solar energy device" means an apparatus designed or adapted to convert the radiant energy from the sun, including energy imparted to plants through photosynthesis employing the
                        bioconversion processes of anaerobic digestion, gasification, pyrolysis, or fermentation, but not including direct combustion, into thermal, mechanical, or electrical energy; to store the converted energy, either in the form to which originally converted or another form; or to distribute radiant solar energy or the
                        energy to which the radiant solar energy is converted.
                        (2) "Wind-powered energy device" means an apparatus designed or adapted to convert the energy available in the wind into thermal, mechanical, or electrical energy; to store the converted
                        energy, either in the form to which originally converted or another form; or to distribute the converted energy.



                        Thank you,

                        Richard D. Kelley, PMP
                        Certified Project Manger
                        Rdkelley@...
                        (281) 933 - 3958





                        -----Original Message-----
                        From: John Miggins [SMTP:jmiggins@...]
                        Sent: Saturday, September 03, 2005 12:10 PM
                        To: hreg@yahoogroups.com
                        Subject: Re: [hreg] Assistance RESPONSE

                        << File: ATT00012.htm >> Thanks for the help Bashir, your calculations helped me clarify the calcuation process and thanks for the clarification Andrew. I appreciate this thread as it goes to the heart of what we often encounter in the solar business. People want to know how long it will take to pay for their system and it often shows a long time, over 20 years. I have struggled with this and asked Bashir for his method thinking that I had missed something. What is true payback period and what is true cost of line power are legitimate questions.

                        I do know that new panels are hot or produce up to 15% more than they are rated to allow for some loss in power over time. a 150 watt panel will actually put out over 170 watts. This should be figured into the equation but a dissipation of this effect will need to be included as well.

                        Incentives are what is driving the market, california being one instance, as well as remote users who have little other choice. For people in urban areas, the payback may be long but seeing what has happened in LA/MS it makes sense to have some solar capability for back-up to run your refrig, phone, some lights and fans in case power goes out. This can be done for $5000 or less and will provide for some security and peace of mind.

                        Payback goes out the window when the power is out.
                        solar thermal makes sense right now, payback is less than 5 years.





                        John Miggins
                        Harvest Solar & Wind Power
                        "renewable solutions to everyday needs"
                        www.harvest-energy.com
                        Phone/Fax 918-743-2299
                        Cell: 918-521-6223

                        ----- Original Message -----
                        From: Andrew McCalla
                        To: hreg@yahoogroups.com
                        Sent: Saturday, September 03, 2005 7:15 AM
                        Subject: RE: [hreg] Assistance RESPONSE


                        All,



                        There are many ways of calculating the "payback" of a pv system...some which make it look more appealing, some which make it worse, some using very basic calculations, some using complex financial analyses and calculated energy projections.



                        The method however, that has been presented in this thread, is most peculiar.



                        First of all, while acceptable to use the NREL average for back-of-the envelope calculations, it probably isn't acceptable to simply de-rate the STC rating of the array by the inefficiency of it as there are many other inefficiencies that come into play by the time the power from the system in question gets put to work.



                        This pitfall is illuminated in the example that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year. To be clear: it would not, at least not in Houston.



                        Secondly, and regarding the basis for the calculations we have seen:

                        It will be very hard to install to functionality a quality 3 kW system installed for $18K. Furthermore, it would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year for $3K). Perhaps this includes environmental costs or other "intangibles", which is most appropriate in a big-picture way, but maybe not so much for a bare-bones payback analysis.



                        I am a pv advocate and I believe that a true accounting should incorporate all social and environmental costs, in addition to the financial ones. However, or perhaps because of that advocacy, I think that a clear representation needs to made as to the limitations, as well as the capabilities, of this technology with respect to people's energy "needs".



                        See below for a more "real world" projection for what the 3 kW system in question might actually do in Houston:



                        Station Identification

                        City:
                        Houston

                        State:
                        TX

                        Latitude:
                        29.98° N

                        Longitude:
                        95.37° W

                        Elevation:
                        33 m

                        PV System Specifications

                        DC Rating:
                        3.0 kW

                        DC to AC Derate Factor:
                        0.770

                        AC Rating:
                        2.3 kW

                        Array Type:
                        Fixed Tilt

                        Array Tilt:
                        30.0°

                        Array Azimuth:
                        180.0°

                        Energy Specifications

                        Cost of Electricity:
                        9.2 ¢/kWh






                        Results


                        Month
                        Solar Radiation
                        (kWh/m2/day)
                        AC Energy
                        (kWh)
                        Energy Value (estimated)
                        ($)

                        1
                        3.68
                        252
                        23.18

                        2
                        4.12
                        251
                        23.09

                        3
                        4.82
                        321
                        29.53

                        4
                        4.98
                        315
                        28.98

                        5
                        5.24
                        335
                        30.82

                        6
                        5.53
                        337
                        31.00

                        7
                        5.43
                        338
                        31.10

                        8
                        5.44
                        342
                        31.46

                        9
                        5.40
                        332
                        30.54

                        10
                        5.19
                        334
                        30.73

                        11
                        4.33
                        277
                        25.48

                        12
                        3.34
                        226
                        20.79











                        Year
                        4.79
                        3660
                        336.72










                        And here for an output projection for the system one might need (with correct array orientation) to hit their 5400 kWh/year consumption mark:





                        Station Identification

                        City:
                        Houston

                        State:
                        TX

                        Latitude:
                        29.98° N

                        Longitude:
                        95.37° W

                        Elevation:
                        33 m

                        PV System Specifications

                        DC Rating:
                        4.5 kW

                        DC to AC Derate Factor:
                        0.770

                        AC Rating:
                        3.5 kW

                        Array Type:
                        Fixed Tilt

                        Array Tilt:
                        30.0°

                        Array Azimuth:
                        180.0°

                        Energy Specifications

                        Cost of Electricity:
                        9.2 ¢/kWh






                        Results


                        Month
                        Solar Radiation
                        (kWh/m2/day)
                        AC Energy
                        (kWh)
                        Energy Value (estimated)
                        ($)

                        1
                        3.68
                        377
                        34.68

                        2
                        4.12
                        376
                        34.59

                        3
                        4.82
                        481
                        44.25

                        4
                        4.98
                        472
                        43.42

                        5
                        5.24
                        502
                        46.18

                        6
                        5.53
                        505
                        46.46

                        7
                        5.43
                        508
                        46.74

                        8
                        5.44
                        514
                        47.29

                        9
                        5.40
                        498
                        45.82

                        10
                        5.19
                        500
                        46.00

                        11
                        4.33
                        416
                        38.27

                        12
                        3.34
                        339
                        31.19











                        Year
                        4.79
                        5489
                        504.99










                        Andrew H. McCalla

                        Meridian Energy Systems

                        2300 S. Lamar, Ste. 107

                        Austin, TX 78704



                        Voice: (512) 448-0055

                        Fax: (512) 448-0045

                        www.meridiansolar.com








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                      • Andrew McCalla
                        Richard, Not much, but at least it doesn t hurt. Tax code specialists please weigh in to correct if need be, but I ve long understood this to simply mean that
                        Message 11 of 11 , Sep 10, 2005
                          Richard,

                          Not much, but at least it doesn't hurt.

                          Tax code specialists please weigh in to correct if need be, but I've long
                          understood this to simply mean that the appraisal valuation is not allowed
                          to increase because of the installation of one of the described
                          systems......... and not that there is some sort of deduction or other tax
                          benefit to that installation.


                          Andrew H. McCalla
                          Meridian Energy Systems
                          2300 S. Lamar, Ste. 107
                          Austin, TX 78704

                          Voice: (512) 448-0055
                          Fax: (512) 448-0045
                          www.meridiansolar.com


                          _____________________________________________
                          From: hreg@yahoogroups.com [mailto:hreg@yahoogroups.com] On
                          Behalf Of Richard D. Kelley
                          Sent: Friday, September 09, 2005 6:10 PM
                          To: 'hreg@yahoogroups.com'
                          Subject: RE: [hreg] Assistance RESPONSE

                          Perhaps this will help!

                          Solar and Wind-Powered Energy Systems Exemption
                          Last DSIRE Review: 08/12/2004
                          Incentive Type: Property Tax Exemption
                          Eligible Renewable/Other Technologies: Passive Solar Space
                          Heat, Solar Water Heat, Solar Space Heat, Photovoltaics, Wind, Biomass,
                          Anaerobic Digestion
                          Applicable Sectors: Residential
                          Amount: 100%
                          Max. Limit: None
                          Authority 1: Texas Statutes § 11.27
                          <http://www.dsireusa.org/documents/Incentives/TX03F.htm>

                          Date Enacted: 1981



                          Summary:
                          The Texas property tax code allows an exemption of
                          the amount of the appraised property value that arises from the installation
                          or construction of a solar or wind-powered energy device that is primarily
                          for the production and distribution of energy for on-site use.

                          "Solar energy device" means an apparatus designed or adapted
                          to convert the radiant energy from the sun, including energy imparted to
                          plants through photosynthesis employing the bioconversion processes of
                          anaerobic digestion, gasification, pyrolysis, or fermentation, but not
                          including direct combustion, into thermal, mechanical, or electrical energy;
                          to store the converted energy, either in the form to which originally
                          converted or another form; or to distribute radiant solar energy or the
                          energy to which the radiant solar energy is converted.

                          "Wind-powered energy device" means an apparatus designed or
                          adapted to convert the energy available in the wind into thermal,
                          mechanical, or electrical energy; to store the converted energy, either in
                          the form to which originally converted or another form; or to distribute the
                          converted energy.


                          Contact:
                          Pam Groce
                          Comptroller of Public Accounts
                          State Energy Conservation Office
                          111 East 17th Street, Room 1114
                          Austin, TX 78774
                          Phone: (512) 463-1889
                          Fax: (512) 475-2569
                          E-Mail: pam.groce@...
                          Web site: http://www.seco.cpa.state.tx.us


                          TEXAS STATUTES
                          TITLE 1. PROPERTY TAX CODE
                          SUBTITLE C. TAXABLE PROPERTY AND EXEMPTIONS
                          CHAPTER 11. TAXABLE PROPERTY AND EXEMPTIONS
                          SUBCHAPTER A. TAXABLE PROPERTY
                          § 11.27. Solar and Wind-Powered Energy Devices.
                          (a) A person is entitled to an exemption from taxation of the amount of
                          appraised value of his property that arises from the installation or
                          construction of a solar or wind-powered energy device that is primarily for
                          production and distribution of energy for on-site use.
                          (b) The comptroller, with the assistance of the Texas Energy and Natural
                          Resources Advisory Council, or its successor, shall develop guidelines to
                          assist local officials in the administration of this section.
                          (c) In this section:
                          (1) "Solar energy device" means an apparatus designed or adapted to convert
                          the radiant energy from the sun, including energy imparted to plants through
                          photosynthesis employing the
                          bioconversion processes of anaerobic digestion, gasification, pyrolysis, or
                          fermentation, but not including direct combustion, into thermal, mechanical,
                          or electrical energy; to store the converted energy, either in the form to
                          which originally converted or another form; or to distribute radiant solar
                          energy or the
                          energy to which the radiant solar energy is converted.
                          (2) "Wind-powered energy device" means an apparatus designed or adapted to
                          convert the energy available in the wind into thermal, mechanical, or
                          electrical energy; to store the converted
                          energy, either in the form to which originally converted or another form; or
                          to distribute the converted energy.



                          Thank you,

                          Richard D. Kelley, PMP
                          Certified Project Manger
                          Rdkelley@...
                          (281) 933 - 3958





                          -----Original Message-----
                          From: John Miggins [SMTP:jmiggins@...]
                          Sent: Saturday, September 03, 2005 12:10
                          PM
                          To: hreg@yahoogroups.com
                          Subject: Re: [hreg] Assistance
                          RESPONSE

                          << File: ATT00012.htm >> Thanks for the
                          help Bashir, your calculations helped me clarify the calcuation process and
                          thanks for the clarification Andrew. I appreciate this thread as it goes to
                          the heart of what we often encounter in the solar business. People want to
                          know how long it will take to pay for their system and it often shows a
                          long time, over 20 years. I have struggled with this and asked Bashir for
                          his method thinking that I had missed something. What is true payback
                          period and what is true cost of line power are legitimate questions.

                          I do know that new panels are hot or produce
                          up to 15% more than they are rated to allow for some loss in power over
                          time. a 150 watt panel will actually put out over 170 watts. This should
                          be figured into the equation but a dissipation of this effect will need to
                          be included as well.

                          Incentives are what is driving the market,
                          california being one instance, as well as remote users who have little other
                          choice. For people in urban areas, the payback may be long but seeing what
                          has happened in LA/MS it makes sense to have some solar capability for
                          back-up to run your refrig, phone, some lights and fans in case power goes
                          out. This can be done for $5000 or less and will provide for some security
                          and peace of mind.

                          Payback goes out the window when the power
                          is out.
                          solar thermal makes sense right now, payback
                          is less than 5 years.





                          John Miggins
                          Harvest Solar & Wind Power
                          "renewable solutions to everyday needs"
                          www.harvest-energy.com
                          Phone/Fax 918-743-2299
                          Cell: 918-521-6223

                          ----- Original Message -----
                          From: Andrew McCalla
                          To: hreg@yahoogroups.com
                          Sent: Saturday, September 03, 2005 7:15 AM
                          Subject: RE: [hreg] Assistance RESPONSE


                          All,



                          There are many ways of calculating the
                          "payback" of a pv system...some which make it look more appealing, some
                          which make it worse, some using very basic calculations, some using complex
                          financial analyses and calculated energy projections.



                          The method however, that has been
                          presented in this thread, is most peculiar.



                          First of all, while acceptable to use the
                          NREL average for back-of-the envelope calculations, it probably isn't
                          acceptable to simply de-rate the STC rating of the array by the inefficiency
                          of it as there are many other inefficiencies that come into play by the time
                          the power from the system in question gets put to work.



                          This pitfall is illuminated in the example
                          that a 3 kW array will provide the 450 kWh/month (average) or 5400 kWh/year.
                          To be clear: it would not, at least not in Houston.



                          Secondly, and regarding the basis for the
                          calculations we have seen:

                          It will be very hard to install to
                          functionality a quality 3 kW system installed for $18K. Furthermore, it
                          would seem that the example case is assuming a $.56/kWh rate (5400 kWh/Year
                          for $3K). Perhaps this includes environmental costs or other "intangibles",
                          which is most appropriate in a big-picture way, but maybe not so much for a
                          bare-bones payback analysis.



                          I am a pv advocate and I believe that a
                          true accounting should incorporate all social and environmental costs, in
                          addition to the financial ones. However, or perhaps because of that
                          advocacy, I think that a clear representation needs to made as to the
                          limitations, as well as the capabilities, of this technology with respect to
                          people's energy "needs".



                          See below for a more "real world"
                          projection for what the 3 kW system in question might actually do in
                          Houston:



                          Station Identification

                          City:
                          Houston

                          State:
                          TX

                          Latitude:
                          29.98° N

                          Longitude:
                          95.37° W

                          Elevation:
                          33 m

                          PV System Specifications

                          DC Rating:
                          3.0 kW

                          DC to AC Derate Factor:
                          0.770

                          AC Rating:
                          2.3 kW

                          Array Type:
                          Fixed Tilt

                          Array Tilt:
                          30.0°

                          Array Azimuth:
                          180.0°

                          Energy Specifications

                          Cost of Electricity:
                          9.2 ¢/kWh






                          Results


                          Month
                          Solar Radiation
                          (kWh/m2/day)
                          AC Energy
                          (kWh)
                          Energy Value (estimated)
                          ($)

                          1
                          3.68
                          252
                          23.18

                          2
                          4.12
                          251
                          23.09

                          3
                          4.82
                          321
                          29.53

                          4
                          4.98
                          315
                          28.98

                          5
                          5.24
                          335
                          30.82

                          6
                          5.53
                          337
                          31.00

                          7
                          5.43
                          338
                          31.10

                          8
                          5.44
                          342
                          31.46

                          9
                          5.40
                          332
                          30.54

                          10
                          5.19
                          334
                          30.73

                          11
                          4.33
                          277
                          25.48

                          12
                          3.34
                          226
                          20.79











                          Year
                          4.79
                          3660
                          336.72










                          And here for an output projection for the
                          system one might need (with correct array orientation) to hit their 5400
                          kWh/year consumption mark:





                          Station Identification

                          City:
                          Houston

                          State:
                          TX

                          Latitude:
                          29.98° N

                          Longitude:
                          95.37° W

                          Elevation:
                          33 m

                          PV System Specifications

                          DC Rating:
                          4.5 kW

                          DC to AC Derate Factor:
                          0.770

                          AC Rating:
                          3.5 kW

                          Array Type:
                          Fixed Tilt

                          Array Tilt:
                          30.0°

                          Array Azimuth:
                          180.0°

                          Energy Specifications

                          Cost of Electricity:
                          9.2 ¢/kWh






                          Results


                          Month
                          Solar Radiation
                          (kWh/m2/day)
                          AC Energy
                          (kWh)
                          Energy Value (estimated)
                          ($)

                          1
                          3.68
                          377
                          34.68

                          2
                          4.12
                          376
                          34.59

                          3
                          4.82
                          481
                          44.25

                          4
                          4.98
                          472
                          43.42

                          5
                          5.24
                          502
                          46.18

                          6
                          5.53
                          505
                          46.46

                          7
                          5.43
                          508
                          46.74

                          8
                          5.44
                          514
                          47.29

                          9
                          5.40
                          498
                          45.82

                          10
                          5.19
                          500
                          46.00

                          11
                          4.33
                          416
                          38.27

                          12
                          3.34
                          339
                          31.19











                          Year
                          4.79
                          5489
                          504.99










                          Andrew H. McCalla

                          Meridian Energy Systems

                          2300 S. Lamar, Ste. 107

                          Austin, TX 78704



                          Voice: (512) 448-0055

                          Fax: (512) 448-0045

                          www.meridiansolar.com









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