A bloke I know pointed out that solar cells are now up to 40 percent
efficient. Couple of things came to mind so I looked up SolarSystems
and see they are using them. So I calculated a few bits for said
bloke. Here 'tis.
A SolarSystem project http://www.solarsystems.com.au/projects.html
Here is more detail, upon which I have calculated some efficiency
So let's see how that works out.
270,000 Mw-hrs per year claimed output.
6 Mw-hrs per year per home
16.44 kw-hrs per home per day (thatís a bit low compared to Western
Australia where the climate is much hotter but otherwise about right
As an aside, what about the other 90 percent of energy that is used by
$20 million cost
$.14 per kw-hr equivalent to 3,000,000,000 kw-hrs, i.e., 3,000,000
But the system delivers only 270,000 Mw-hrs per year. Ergo, system
will have to be in operation for 11.1 yeas before it pays for its
What is the running cost?
154 Mw per 800 hectares.
8e2 * 1e2 * 1e2 = 8e6 sq metres.
Insolation is nominally 1 Kw per sq metre at normal incidence.
System should deliver 8e3 Mw at peak efficiency. Ergo, ground cover
efficiency is only 154/8000 = 1.9 percent!!!!
With efficiency this low my calcs suggest we will have to cover 75
million sq kilometres with such collectors by 2050 to satisfy world
energy needs. I can't see it happening
Finally, am I Robbie Crusoe or has anyone else wondered what happens
to the 90 percent (or more) solar energy that is absorbed but not
converted to electricity? As far as I can see it will be dissipated
into the environment as waste heat. It seems to me that it will add to
global warming. Of course some will eventually be radiated into space,
a least that part that doesn't get trapped by the CO2 but overall it
seems to be to be counterproductive.
This is extraordinarily depressing.
** Posted from http://www.teranews.com **
I think your question boils down to whether the albedo of a solar
panel is lower than that of the surface it's replacing.
Lower albedo generally means increased heat conversion. Even though
some 10% of light hitting a panel is converted to electricity instead
of heat, eventually nearly all of that electricity WILL end up as
I suspect there isn't really much difference. Most of the time,
you're covering roof space with solar panels. I doubt that there's a
big difference in effective albedo between a typical roof tile and a
solar panel. You should be more concerned about home and asphalt road
construction, if you care to feel depressed about such things. PV's
net effect, by decreasing GHG emission in the long term, is likely a
Only mega expensive space ones. More like 15% for what you can buy at
slightly more same prices.
Where did you think 100% of the insolation was going before the solar
panel was placed there? If you must be depressed about something,
pick something real. There's NO net difference here!!!