RE: Concentrating Solar Energy
- To: "'domesteading at sculptors dot com'" <domesteading at sculptors dot com>
- Subject: RE: Concentrating Solar Energy
- From: John Atkins <jatkins at technistar dot com>
- Date: Wed, 29 Apr 1998 08:19:38 -0600
- Return-receipt-to: John Atkins <email@example.com>
Yeah. There's two limitations offhand:
1. Heat. Photovoltaic cells can only take just so much heat. I'd
leave any more than 2x or 3x to the scientists for now! Excess heat will
lessen the life of the panels. 100 suns can probably melt metal - we
used to melt pennies with a big Fresnel in the back yard.
2. Tracking. You have to accurately position (and move) the panels
to concentrate the light from the Fresnel onto the photovoltaic panel.
The more concentration, the more accuracy required.
You can also do the concentration at the 2x or 3x level with mirrors
hung off each side of the photovoltaic panel, the way solar food ovens
work. This may be easier and cheaper for home, as big Fresnels are
pricey and degrade in the sun. If they were my panels, I'd try to mount
a heat sink on the back side of each, at least for desert/high altitude
I know that somebody was making or still is making Fresnel concentrator
panels for home use.
From: The Butterfly [SMTP:salsbury at sculptors dot com]
Sent: Tuesday, April 28, 1998 8:44 PM
To: domesteading at sculptors dot com
Subject: Concentrating Solar Energy
Another interesting bit...
In that article about the new solar cells, they were
concentrated light to get faster results, so that they could
efficiencies and so on. The light source they used was "11
suns", or 11x
the normal solar light level.
They talked about some of the large-scale solar power
stations, and how they used solar concentration to get "100
suns" of energy
to work with.
This got me thinking about scaled-down applications in
use. Why not use arrays of mirrors and/or Fresnel lenses to
more solar energy onto your solar cells, or solar water heaters?
can get more energy out of the same amount of solar cell
heat out of the same amount of black water pipes, etc.
I'm not sure what the operating tolerances of commercial
solar cells are, but they're certainly more than one "sun". The
example of 100 suns was probably the extreme of the high-end
they use for space applications and the aforementioned solar
the article did mention a target range of 10-20 suns for common
You can buy large Fresnel lenses from Edmund Scientific
scientific supply companies for a reasonable price. My current
catalog has 11" square sheets for $12. They used to sell ones
2'-3' in diameter, but I don't see one in this catalog.
Still, the price is quite cheap for making solar
probably give a 2x or greater increase in energy for the solar
Has anyone done any work with this? John Atkins? You
used to play
with Fresnels, didn't you?
Patrick G. Salsbury -
Check out the Reality Sculptors Project:
Politicians are the root of most evil.
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