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A Different Form of Solar

Posted: Mon Dec 03, 2018 9:20 pm
by Farside
I think it's worth having a section here on solar heating, cooking, and driving engines directly from the sun's rays.

Re: A Different Form of Solar

Posted: Wed Dec 05, 2018 1:27 pm
by Farside
I think it's worth keeping an eye out for those old rear projection televisions that people give away. The Fresnel lens that makes up the screen is a critical component for harnessing useful amounts of solar energy, and I don't think these are being manufactured anymore.

Re: A Different Form of Solar

Posted: Wed Dec 05, 2018 2:06 pm
by Farside
Another useful technique involves making large parabolic mirrors (actually it's a spherical mirror but it's close enough) out of those silver mylar space blankets. By securing them to a rigid form, and creating a vacuum in the space between the film and the form, you get a good enough parabolic mirror for use in solar cooking and energy production.

You can also adjust the focal length of the mirror by adjusting the vacuum strength. I've experimented with this technique, and by far the trickiest part is creating a reliable seal between the film and the former so that air doesn't get back in and deform the mirror. My biggest challenge has been where the mylar is folded upon itself where it contacts the frame.


Re: A Different Form of Solar

Posted: Mon Jan 28, 2019 5:50 am
by SmartLikeTruck
I clicked on this thread fully expecting to see Minto wheels, which is somewhat low temperature differential thermal to mechanical energy without the precision machining for a stirling engine.

I've played with parabolic mirror setups, the tracking setup is where it gets complicated, if I was to follow up I'd do parabolic trough that way you only need to track the sun on one axis.