One thing I'm considering doing is getting with a few friends and going to buy a pallet of panels. The ET Solar panels which are 36 volts and 8.8 amps selling for ~$300 each or $7000 for a set of 26 from Wholesale Solar can be useful for all parties involved. Just one mounted atop a trailer can keep my battery topped off without having to resort to the generator. Other panels always come in handy. Having one 15A circuit at one's stick/brick house that is just powered by solar and batteries, and intended for low-draw stuff (laptop/cellphone/tablet chargers), would help a bit on the electric bill, but would get the parasitic loads off the mains power, and also offer a circuit that is guarenteed to be live in case of a power outage (so the refrigerator can be plugged into it, for example.)
Of course, since this is a 36 volt panel, a MPPT controller is a must, unless I want to chop off 2/3 of the incoming wattage. Maybe BFL13 is right with wasting money, but I'm going with a more expensive CC, even if it is a no-name Chinese model that is no-frills, but can get the right power to the batteries at the stage of charging needed.
The solar charging system for my RV and cargo trailer is less about money, but more about being able to be at a festival where most people are tenting it on weekends, and not have to wake up the neighborhood by starting up a generator, even a super-quiet model. That, and passively keeping batteries charged to compensate for the energy lost due to running the furnace at night.
Plus, it is a cool tinkering project. Good, reliable power without having to pay for the local utility to come string a line, or have to fire up a fairly high cost/watt generator. Always a nice thing to have.
