Well I spent most of 2009 developing a heliostat prototype, and over the last year I've realized that I'm not in the position to go entrepreneurial with it so I'm just putting it out there....
heliostat.sourceforge.net is the home page. It's spankin' new and I'll flesh it out a little better soon.
I started the project with the 328 and filled that up, then split tasks between two 328s communicating over I2C, then found out the solar code wouldn't fit at the same time that the Mega128 support came out, so that was cool. I use a simple TIP 12X H-bridge to drive two satellite dish linear actuators. They have a reed sensor that gives a pulse which is hooked up to an Arduino interrupt for position sensing. An old bicycle frame turned upside down and slightly modified made a great Alt-Azimuth mount. I used a basic LCD keypad shield for user I/O to keep things cheap. The prototype stand with a 4'x4' mirror assembly mounted has even survived a thunderstorm with 40mph gusts and 3/4" hail without any damage to the mirrors.
I've developed this entire project while largely unemployed and semi-homeless, which has at times given it a rather surreal feeling. Whatever was at hand that could be used got used, and purchases were kept to a minimum. Without wasted dead end R&D expenses, the basic prototype that I built could be duplicated for about $350.
The perhaps more complicated part has been building a suitable target device. I've almost finished a bio-mass fueled water heater design that only needs a slightly different heating element for solar use. I've learned that boilers can be dangerous if you don't have the right regulators! If I can just get the wiring right on the DS18b20 sensors then I'll be able to finish my Temperature Differential Controller project.
The vision is to have a small residential "farm" of heliostats that act as slave devices to smart targets which act as master devices in a dynamically distributed solar energy network, with various priority levels for targets resolving allocation conflicts at the heliostat level. All this going over an XBee network would be cool.
Comments, suggestions, support, and encouragement are all appreciated.