A lot of the solar technology that hits the news tends to be a bit on the high-tech side, such as photovoltaic and concentrating solar power devices, but taking advantage of free energy from the sun doesn't have to cost a ton of money, as there are low-tech methods of using solar power to do the work without electronics, wires, or requiring an engineering degree.
This little solar cooker project is a great example of that, because with just a handful of common household materials and a bit of time and creativity, you can create a personal stove capable of reaching temperatures between 250° and 375° F, powered solely by the sun.
Instructables user sclausson has created a step-by-step guide to what is dubbed the Purple Fig Solar Cooker, and it can be built with items that are both cheap and easy to find. The whole materials list consists of posterboard, aluminum foil, some glue, a shoelace, and a couple of binder clips (and some purple paint - after all, it is named the Purple Fig solar cooker).
According to sclausson, the total cost for the materials should be under $5 (and probably free for those with the materials already at hand in the home or office), which means that I expect all of you to build one this week and cook your lunch in it.
The posterboard forms the structure of the cooker, the foil provides the reflective surface for concentrating the rays of the sun, the glue holds the foil to the posterboard, and the binder clips hold the device in shape. I won't tell you what the shoelace is for, as you'll need to head over to Instructables to find that out (but I will tell you that it is a key component of the design). While the finished product is small in size, it does seem as if this solar cooker design could also be easily scaled up to fit the size of the materials you have.
Check out the Purple Fig Solar Cooker at Instructables, and if you do end up building one, we'd love to see your pictures.