I just made an instructable and entered it in the green competition. Way too late of course.
the picture shows the generic driver of a battery wall clock.
I have adapted one by removing the 2 concentric pipes in the middle that run the minute and second hand to just leave the hour hand driver that i use to drive a "gear" wheel.
Anyway, the idea is to do a little dismemberment of clocks, and use the little drive mechanism to control the turning of a solar reflector to continually have the sun focused on what you cook. My current edition of it seems to be working.
I believe a simple tracker is sorely needed for solar applications.
Once a reliable one comes on the market, you may see new backyard applications popping up. For instance, I cook soil! I stick it in a big black pot, and steam it in my tracking solar cooker for a day. This generally reaches 60 or 70 C (It is a big pot and soil has a low thermal conductivity) which is enough to kill seed eating bugs and weed seeds. I end up with excellent home made seeding soil.
Solarization is also possible. Again, a big pot or can, put in all your rotten insect infested fruit, cook for a day, and next year, less bugs on your trees and less sourse of fungal infection.
It might even end up as a stage in the processing of compost. Lots of weed roots and seeds survive the compost heat. But they might not do so good after a day at 70 C!
Tracking might even be accurate enough to make quicklime!
Quicklime is made from limestone CaCO3 that is heated enough to drive off the CO2.
You then slake the lime (add water) and it gives off a lot of heat.
Heat storage potential? and you have Ca(OH)2 which is the basis for lime plaster.
Parabolic dish concentrators can get hot enough to cook limestone. but I do not know the details.
There is more of but that will do for now.
I hope people try this and prove to the holy free market that simple trackers are needed!