## [hreg] Assistance RESPONSE

Expand Messages
• ... 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
>
>
>
>
>
>
>
>
>
>
>

• 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) (\$) 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

• 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) (\$) 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

• 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)(\$) 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 (Message over 64 KB, truncated)
• 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

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) (\$) 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

• 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)(\$) 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
• 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.

“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 -----

From:

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 (Message over 64 KB, truncated)
• 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 -----

From:

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

• 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)(\$) 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  (Message over 64 KB, truncated)
• 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
(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
(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

------------------------------------------------------------------------------

a.. Visit your group "hreg" on the web.

b.. To unsubscribe from this group, send an email to:
hreg-unsubscribe@yahoogroups.com

------------------------------------------------------------------------------
• 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
(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
(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

----------------------------------------------------------------------------
--

a.. Visit your group "hreg" on the web.

b.. To unsubscribe from this group,
send an email to:
hreg-unsubscribe@yahoogroups.com

c.. Your use of Yahoo! Groups is