From: James Rogers (jamesr@best.com)
Date: Wed Sep 06 2000 - 06:10:28 MDT
On Wed, 06 Sep 2000, you wrote:
> Eugene Leitl wrote:
>
> > 2) solar cells do not require direct sunlight to generate
> > juice. diffuse daylight does nicely, especially when we're talking
> > about amorphous cells.
>
> Sure, but their efficiency decreases as flux decreases, and total flux does
> decrease with diffusion, as visible is converted to IR. If your flux drops by
> half due to diffusion by cloud cover, and the efficiency drops as well as flux
> drops, your output decreases markedly.
My understanding, from doing some research into solar electric out of
necessity, is that even the best locales in the U.S. in terms of available
sunlight throughout the year (such as Arizona), don't average much better
than the equivalent of 5-5.5 hours of full-flux exposure per day over a
year's time. So while diffuse light may offer some power, it seems that
it is only a minor contributor to the total output. Most power generated
in PV systems appears to be during that relatively narrow window of peak
solar flux.
-James Rogers
jamesr@best.com
This archive was generated by hypermail 2.1.5 : Fri Nov 01 2002 - 15:30:49 MST