@fireflies
Thank you for your input. I have created some spreadsheets that do calcs (how long does it take to drain a battery given a certain load, how long it would take to charge a certain battery from a solar panel of a any wattage, how many batteries to power a load, etc). Nothing as fancy (or as thorough) as your contact. It's an interesting learning curve.
@dbindoff
I have purchased and can power a 400W heater for several hours from a 225AH battery I purchased dirt cheap from a golf course (old golf buggy deep cell that I've reconditioned with a little tech from John Bedini). I only need the heat in bursts so I can make it last an entire day (more so at night, so the battery gets topped up by my cheapie 60W solar panel throughout the day). Charging up the beast takes some time of course. So really I'd need 2 of these batteries; use one while charging the other, then swap the next day. I'm also playing around with various solar panels (and using mirrors to boost the power - see http://www.youtube.com/watch?v=o_cEYld4LiU for ideas). Also see this YT vid for ideas, including US$1 per Watt DIY solar panels (http://www.youtube.com/watch?v=hNH2YGzwznI).
Now, slightly off topic, but still interesting non-the-less (well, for me anyway) ...
I'm also playing around with using LEDs, diodes and transistors that I've pulled out of old TVs, radios and other electronics at the tip. LEDs, diodes and transistors act like a solar panel and provide free DC electricity when light in shone on them. Shine a light on a single red LED and you'll get 1.3v; 2 LEDs and you'll get 2.6v etc. I duplicated what this guy is doing as an experiment -> http://www.youtube.com/watch?v=oEoCb1ycwEE
I don't have very many strung together at present, but enough to charge a small lithium battery that powers a 6w LED bulb (the equiv of a 35W incancdecent) - which is enough to provide a light over my desktop & keyboard when the sun (light) goes down late afternoon. It'll last all night long, charges itself through the day, then I use it again at night. When I get more LEDs and diodes going I'll be able to power more lights. It's fun experimenting. I want to experiement with a Joule Thief next.
I also want to attempt to replicate another experiemtn I've seen - powering a CFL light with a 1.5v battery (with the aid of a high voltage circuit from a disposable camera). The CFL can be powered for days with a single 1.5v. Mak it a rechargeable battery, charge it with a solar panel, and you've got a high lumen light forever pretty much for free. I'll include the YT link if anyone is interested.
Again, I got my red LEDs from discarded electronics.