Here's my cheapo setup. That mini- Altoids tin has a voltage regulator circuit I built and what you can't see is a trimmer pot connecting pins 2 and 3 of the chip to make it variable. I've premarked points on the pot to match other device voltages. I could make it smaller but the thing weighs about an ounce as it is. The pictured battery is a 12vdc, 1.4ah gel cell that will last me a week of 1 watt transmitter time, and charge other devices as well. That battery costs about $6 and is basically a chunk of lead in weight, but is very forgiving with respect to charging scheme. Lithium batteries are much lighter, way more expensive, and a bit more picky about how they are charged. All my lithium batteries are salvaged from cell phones, however. Anyway, like you said NiytOwl, most of the time we aren't out that long and this setup is lighter than a solar array and much more reliable. I've never lost a coin cell or run one down in my led light, and I don't bother with hauling extras. My stuff is designed around remote amateur radio operation. A system could easily be optimized based on specific hiker needs and weight cut to a minimum.