I'd also like to learn about solar power...but why not focus on reducing power usage first.
I run a fishroom pushing 60 tanks, including a 180g, two 150g and several other large tanks on ~ $100 per month by:
1) Only heating tanks that need it (fishroom's in my basement and stays at ~70F in the winter, slightly warmer in the summer), I keep mostly Central American and Uruguayan cichlids and livebearers. I have more spawning than I know what to do at the lower end of the temperature scale.
2) Running almost exclusively air-driven (box, sponge, Poret w/air lifter) filters. Big pumps and canister filters suck power. On my larger tanks, I user "dump" filters (sump on top of the tank) and get much more flow at lower power use because of less head loss (than a sump that requires 6 foot or more pumping uphill).
3) Overhead lighting and use of timers. I have overhead vs. individual lights on the tanks in my fishroom. When I'm at work, I have one 14W fluorescent bulb for the whole room...when I'm home, I light the whole room with 64W...but only when I'm in the room. The fish don't need it.
When I hear about people filtering tanks with multiple FX5s, monster pumps, keeping them at 86F, keeping heavy lights in 24x7, I cringe. Less is more
Matt