John Steck wrote:
Wandering into this project about as green as they come (pardon the pun).
I started my research with this as a system baseline:
http://www.realgoods.com/renew/shop/product.cfm/dp/1800/sd/1804/ts/2012239
Whoa! $8,900 for 2.3 kWh/day?!? That's 100 watts average power (over 24
hours), or $89,000 per kilowatt of generator capacity. That's insane. Is
that correct?
This web site claims the cost is $4 per watt-hour, which would also be
insane . . . Do they mean per watt of capacity?
http://www.solareco.com/articles/article.cfm/id/29
I believe the Japanese PV program makes more sense. The industry has
lowered the cost considerably, much of Japan has bright sunlight for most
of the year, and electricity in Japan is much more expensive to start with.
They claim the cost is now 500 yen per watt of capacity ($4.50). See:
http://www.southeastgreenpower.net/2005/presentations/ChrisOBrien.pdf
By the way, p. 12 of this document shows Fresnel lenses being used with PV,
with "record high conversion efficiency."
Comparing this to other energy sources is a can of worms because solar is
only available for about a third of the day, but on the other hand it
always shows up just when you need it most, for air-conditioning. Wind
turbines are intermittent and they may produce peak power in the middle of
the night when you do not need electricity.
This site makes dubious claims about longevity: "PV modules last a long,
long time. How long we honestly don't yet know, as the oldest terrestrial
modules are barely 30 years old, and still going strong. In decades-long
tests the fully-developed technology of single- and poly-crystal modules
has shown to degrade at fairly steady rates of 0.5% to 1% per year." NREL
and industry sources I have read say that after 20 years most PV modules
degrade so much they produce between one-third of the original output to
nothing, and they are not worth maintaining.
All in all, while I love the idea of PV electricity, I think spending
$8,900 for this is crazy. You would save more energy investing that kind of
money in insulation and improved lighting and appliances.
- Jed
