Hello, in this Instructable I will show you how to generate solar power using inexpensive solid state parts and without PV (photovoltaic) cells or panels. I wanted to make this project to see if I could beat the dollars per watt costs of commercially available solar panels.
You only need a few inexpensive parts to build one. It is pretty easy to build and very simple. As far as I know, my idea for the combination of thermoelectric coolers and Fresnel lenses is original... but it's probably not.
Sorry about the rubber bands and foam but remember this is an experiment on my part. Rubber bands are just the best thing for me! Likewise, I recommend you also build a prototype and if (when) it works you should go on to more fancy enclosures. Remember this is just a rough guideline and you can modify it however!
How it works:
This generation method uses a Peltier cell to generate electricity. Peltier cells are designed to be used as heat pumps. When you apply power to a Peltier cell, it begins pumping heat, and one side becomes cold and the other, hot. However, you can do the opposite and generate power from a temperature differential on the sides. To generate this differential, a Fresnel lense focuses light onto one side of the Peltier, and it becomes hot. The other side has a heatsink attached along with a fan that is powered by the Peltier.
Lenses concentrate light, which is absorbed by everything, and when light is absorbed, heat is created. You can easily burn yourself and other things with the lens. Don't leave this out uncovered because the sun moves and it might focus on something. I disclaim all responsibility for anything ever.
Step 1: Parts and Tools
a Peltier cell (I got a 50W one for $5 off of eBay, they are still there)
a Fresnel lense (mine's about the size of a sheet of printer paper, there are a whole lot on ebay)
a CPU heatsink (any type of heatsink will work, as long as it's big enough. I got mine at a garage sale for $2.50)
a 5V fan (more info on that later)
Black paint (I used semi-flat spray paint and it didn't burn)
Note on the peltier: The wattage doesn't affect the power output, but it does affect the internal resistance, which in turn affects the voltage output. Higher wattage = lower voltage, higher amperage. You want a lower wattage peltier so the voltage output is high enough.
My dad built a DIY projector and one of the Fresnel lenses he bought was scratched so he gave it to me.
Warning about the Fresnel! Don't go much bigger than the sheet-magnifier size because you will fry your Peltier. We are probably already running it over it's heat limit, which means it may not last as long.
We have a bunch of foam lying around from building RC foamy airplanes.
The heatsink used to have a fan on it but it was 12v and barely ran off of 5v, so I hunted for 5 volt fans. I was impatient and couldn't find one that I could purchase locally, so I went to Fry's electronics and picked up a laptop cooling pad for $10. There is another one there for $5 that will work fine. It had two fans built in, so I took out the 6 screws, pulled it apart, and pried off the two fan blades/circuit boards. As you can see, they were smart and made the fan axles built into the case instead of standalone fans... so I outsmarted them and dremeled out the axles! You could go my route and use a band/jig saw or dremel, but I highly recommend buying a 5v fan online to save yourself the trouble.