Step 12: Conclusion
Clearly, a giant Fresnel lens with an area of ~1.2m2 is a powerful asset. Assuming the maximum available solar energy hitting the ground is around 1000W/m2, this lens could theoretically concentrate 1200W of power into a square centimeter. Of course, at this latitude and time of year, around half of the maximum sunlight is available so this would make an excellent summer project. But even during winter, the fact that I could easily melt solid copper and make a nickel red hot is pretty damn cool.
There are a good number of websites about the joys of giant Fresnels, namely:
- "Now We're Cooking with Light"
- "Random Destructive Acts via Focused Solar Radiation"
- "How to Melt a Penny"
- Howstuffworks Article
- Wikipedia Article
Perhaps the most valuable thing you can get out of this instructable is the source for these giant lenses. There are loads of of them heading for landfills, or recycling, or god knows what else, so reclaim these things and put them to use!
Note: You may think, as I did, "Gee, I bet I could make a super efficient solar panel with one of these". But according to this discussion board that isn't a very good idea, and could ruin your expensive solar panel. You could certainly power a small heat engine like this stirling engine though, by trapping all the light in a black container thermally connected to the boiler. A company working on this technology, but using reflectors instead of lenses, is Stirling Energy Systems.
Thanks to everyone for your comments and suggestions.
Special thanks to foobaz utne for solving my problem with the Fresnel lens focusing properly.
I hope you enjoyed this project, and I will either update this if I further develop it, or post other solar-related projects in the future.