[diemos]

I downloaded a pamphlet from NREL on payback times in solar PV systems and the numbers didn't seem to add up. http://www.nrel.gov/docs/fy04osti/35489.pdf

They said that a meter square panel would see 1700kWhrs/year in a good sunny location. At 12% efficiency that's 200kWhrs/year. Those numbers I understand and agree with. Then they claim it takes 600kWhrs to make the silicon (plus 200kWhrs for the other components of the panel) and determined an energy payback time of 4 years for amorphous silicon. So far so good.

Then I said to myself WTF? At $0.05/kwHr wholesale this panel is going to produce $10/year of electricity. If I assume $2/Wpeak (which I certainly wasn't finding retail in a casual web search) a m2 would be $240 giving an economic payback time of 24 years.

Why is the economic payback period so different from the energy payback period? Well, obviously it's got to be salaries and capital costs. So when we calculate EROEI don't we have to include the energy consumed when the workers spend their paychecks and the energy used to build the production plant? Does the oil industry extract oil with a lot fewer workers / capital costs?

Signed, perplexed

[Tyler_JC]

They have to cover the research and development cost of the technology.

You are buying a complex piece of technology.

The panel might cost $2000 to build on the margins but you have to pay for your tiny piece of the factory, the CEO salary, the tax bill, the water bill for the company restroom, etc, etc, etc. All of those costs add up and have nothing to do with energy.

Just like the cost of a sandwich at McDonald's isn't just the cost of the meat, bun, and ketchup. It is also the implied cost of the employees, building maintenance, advertisement campaigns, etc.

[Newfie]

Overheads and adders can be astounding.

In my consulting industry these are typical numbers:

$100 paid to the employee for consulting services.
$150 for overhead including benefits, taxes, retirement, health, marketing, offices, staff, etc.
$250 sub-total
$25 fee on sub total
$275 billing to client

[Keith_McClary]

I notice on this PO.com page there are "Ads By Google" for Earth4Energy$this->bbcode_second_pass_quote('', '
')At Last! A complete step-by-step guide to make
solar panels at home and create electricity!

"Michael's complete step-by-step fully illustrated manual will have you generating your own electricity for less than $200!"

From the workshop of Michael Harvey
Renewable energy enthusiasts
and creator of Earth4Energy.com

[kuidaskassikaeb]

Um, I think you also have to include the add ons for electricity. When I divide my electric bill/ by the KWH I don't get $0.05. It's more like $0.30. We don't use much, so that's high, because it includes fixed charges like hook up. But even the costs that track usage are like 0.15. Comparing wholesale costs might make sense for comparing a utility panel system with a coal plant, but for home use nah.

[vtsnowedin]

Solar panels do not make any sense now with grid power at .07 to .18 per kwh. After the peak when the grid is down or they are charging you 2.00/kwh they will make perfect sense but the demand will far exceed supply. So avoid the rush and get them now while the getting's good. If the grid never goes down you have an expensive toy that wastes less money then an RV and fishing boat and if the grid does go down you will be the family hero. This is a faith test for the Peak Oil religion. Truly penitent men will buy enough PV panels to be independent of the grid at least when the sun is shinning.

[AgentR]

The most useful thing about solar panels remains that they generate power where it is expensive or impossible to run commercial power to. This is especially true in locations where having no power is really annoying, but where having a small amount is very useful.

[vtsnowedin]

$this->bbcode_second_pass_quote('AgentR', 'T')he most useful thing about solar panels remains that they generate power where it is expensive or impossible to run commercial power to. This is especially true in locations where having no power is really annoying, but where having a small amount is very useful.

[shortonoil]

diemos said:

$this->bbcode_second_pass_quote('', 'W')hy is the economic payback period so different from the energy payback period?