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Hi Eric,

Perhaps you were thinking of this "Solar Death Ray"? :-)
http://www.solardeathray.com/ 

It doesn't have to be a single concave mirror, but I imagine the collectors
being 100+ feet away from the solar panel (with the same focal length).
It's still a dangerous, adult-supervised activity, as you could put an eye
out, but you wouldn't melt your hand unless you were near the focal length
and the students were quite accurate with their mirrors.  Perhaps the
collectors could be positioned around a circle, each with their own target
solar panel and energy gauge, to disperse the heat and provide some
competition.  

Even so, the heat may still be too much of a hazard, and the solar panels
may not be able to convert the additional light into electricity, but it's
worth an experiment.  On the other hand, you may find that students will
have a hard time focusing their mirrors on a tight spot at 100 ft or more,
making the collectors relatively safe.  I wouldn't give up at the hint of
danger until you've experimented a bit to find out what the real risks are.
The first obvious rule is to make sure every collector is only designed to
point upwards.

Good luck!
Eric



-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]] On Behalf Of Eric Siegel
Sent: Sunday, February 22, 2009 1:36 PM
To: [log in to unmask]
Subject: Re: [ISEN] Earth Day

ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related
institutions.
****************************************************************************
*

I wouldn't try using concave mirrors (which is what I think you mean  
by solar collectors).  I intuit, without any real experience, that  
this could be dangerous.

Eric Siegel
esiegel at nyscience dot org

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