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RE: [hreg] Assistance RESPONSE

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  • 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 1 of 11 , Sep 3, 2005
    • 0 Attachment

      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 2 of 11 , Sep 3, 2005
      • 0 Attachment
        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 3 of 11 , Sep 4, 2005
        • 0 Attachment

          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 4 of 11 , Sep 4, 2005
          • 0 Attachment

            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 5 of 11 , Sep 4, 2005
            • 0 Attachment
              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 6 of 11 , Sep 9, 2005
              • 0 Attachment
                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 7 of 11 , Sep 10, 2005
                • 0 Attachment
                  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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