Hello everyone! Hola a todos!
My name is Josema and I'm from Spain.
After several weeks of searching for information and some Do It Yourself, I finished my heliostat / Sun tracker.
It moves a 20w solar panel or a mirror 35x50cm sized. (I'm currently testing both configurations)
I used two car window motors, whose DC motors I replaced by stepper motors. They have a worm gear with a 70:1 reducing ratio. If we consider that the stepper motor coupled to its axis have 200 steps, we get 14000 steps per 360º to rotate the heliostat in azimuth, also in elevation. This is a theoretical resolution of 0.025 degrees per step. Not bad!
The movement is amazing and accurate.
I added a RC transmitter joystick to adjust the mirror position to the chosen target without a computer.
All electronics are powered by a 12V battery.
You can see more pictures in this link (spanish language): http://puspis.blogspot.com.es/2013/07/siguiendo-el-sol-o-como-meter-un.html
And this video on Youtube, where you can see how it changes from heliostat to solar tracker: https://www.youtube.com/watch?v=OkmI0UgYbzk
Thanks to Gabriel Miller for their great work and thanks to Google Translator for helping me to translate this text.
Best regards from Spain. Josema