Dear Mr. EcoGeek,
I've heard that it takes more energy to produce photovoltaic cells than the cells will ever produce throughout their lifetime. Is there any truth to that, or are those naysayers just saying nay?

David
Spokane, WA

Short Answer:
Those naysayers are just saying nay! But that doesn't mean there's not more to this story.

Long Answer:

This myth was probably perpetuated by studying solar panels created for NASA. If you need something extremely efficient for use in outer-space, yes, then it doesn't matter how much energy you use to create the panel. But for use hear on Earth, it's ridiculous for anyone to say that solar panels consume more energy than they produce.

Of course, doing anything in this world takes energy. Whether it's building power lines or shipping oil from Saudi Arabia, it takes energy to make energy usable. In fact, there's a nifty number that puts all of this into perspective. It's called the “energy balance”, and it is, in short, the amount of energy you get out divided by the energy you put in.

So, for corn ethanol, for example, we get 1.3 units of energy for every 1 unit we put in, so its energy balance is 1.3. Whereas for Brazilian sugar cane ethanol, we get 8 units of energy for every one we put in. As for gasoline, its energy balance is about 5.

So what does this have to do with solar? It is a bit incorrect to apply energy balance to solar panels, because they don't actually contain the energy, so it's not something that I've ever actually seen done. But I think it makes sense to fudge it a bit in light of your question.

Data from a study(pdf) from Energy Environment and Economics Inc. showed that the average solar panel gets five times more energy out than was originally put in. Roughly the same “energy balance” as gasoline. 

Still, no one is satisfied with that number.

As PV material (usually polysilicon) is energy intensive to create, a lot of folks are trying to figure out how to use less of it. One common method is to use mirrors or lenses to concentrate the sunlight on a relatively small amount of polysilicon material. Additionally, a whole other branch of the solar industry is trying to make solar panels from less energy intensive materials, including the much touted copper indium gallium selenide (CIGS) thin-film solar panels.

There may be some economic reason to not be an early adopter of solar, but there is certainly no doubt that they produce a lot more energy than they consume. And soon, they'll be producing even more.

Comments (7)

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Love Love LOVE this blog!
written by Thursday , July 13, 2007

Thanks for running it!

Great question, this - I'd heard the same claim, but pretty much ignored it (considering the source). Nice to have an answer.

I'm looking to become an electrician, specializing in green-power conversions. Even after the local housing boom slows, there will be plenty of work for me; and I can feel good about it, too.

Are you familiar with micro-hydro generators?

using solar panel energy to make solar p
written by Johan Smit , July 13, 2007

and probably dumbfound the people trying to make the sums...

VP
written by Kristina , July 13, 2007

One very exciting technology that promises to bring the cost of solar energy down considerably is currently under development by Tempronics out of Tuscon, AZ. Using the principles of heat conversion via nanometer thermotunneling, Tempronics devices can dramatically reduce the cost of converting the sun's energy into electricity. Check it out at: http://www.tempronics.com

Sounds reasonable - then why don't we se
written by Dave , July 17, 2007

The process uses less silicon, and energy per panel. interested in your opinion. http://solar.anu.edu.au/docs/0...nology.pdf

answer fast
written by luma , January 15, 2008

hi my name is luma and im from jordan and i want to ask you if we can buy this innovalight ?
how much it would coast us ?
and how fast can you deliver it to the middle east??
thanks alot

...
written by David Stupka , March 29, 2008

Are there any green home developments, where all homes sold are green homes?

% of energy produced by solar panels
written by April Renae , April 16, 2008

im doing a project and i need to know how much energy is produced by one solar panel!!!
PLEASE HELP ME!!!!
thanks
april

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