One day I was watching greenpowerscience on youtube and I saw them boiling water with parabolic mirrors. I thought that was the coolest thing since sliced bread and I wanted one, it turns out these puppies were pretty expensive, but they worked really well so I will probably end up getting one sometime in the future. Until then, I have one that I built, here is how I did it:
I started with a box of old cd’s that I got from various ISPs and a five foot diameter satellite dish that I got off Craigslist for $20. The wire mesh dishes are easier to work with because you don’t have to drill into it. Basically all you have to do is attach the CDs shiny side up to the mesh of the dish, as close as you can get them together. You can attach them a variety of ways, the cheapest being drilling two small holes in the clear part of the cd, threading wire through it and twisting it around the mesh of the dish, it works great and you can attach a whole dish worth of cd’s for $20 in wire.
The other method is to use carriage bolts through the center of the cd and thread a nut on to secure it to the dish, this is very expensive and very heavy, but it looks better…its up to you, I use wire. Either way you do it attach the cd’s tight enough so that they will not move.
Next find your focal point, this is dangerous as the focal point is very hot and very bright, wear welding gloves and goggles to protect you from burns. Take a board and hold it out in front of the dish moving it up and down until you find the most concentrated beam, measure how far from the bottom of the dish that point is.
Next build your heating platform, take 1/2″ steel pipe and attach it to the edges of the dish forming a tripod supporting a thick steel plate. Build a metal box around the plate and this is your oven. You can cook anything in here. You can control the temperature by covering the surface of a section of disks with a non reflective sheet.
What else can you do? You can attach a boiler to the plate and generate steam that will run a steam engine, you can attach a Concentrated Solar Plate under the steel plate and generate solar electricity. You can attach a coil of copper tubing to the plate and run water through it to create hot water, very hot water. You can light just about anything you want on fire. You can flash cook food by holding it under the plate in the beam. You can run the hot water into radiation lines in your house to heat your house in the winter. The possibilities are nearly endless. If you live off the grid or in a natural disaster zone this collector can cover many of your needs that you usually couldn’t have without standard utilities.