Thats a interesting site! The Big Island has a bunch of these setups over there where the utilities arent brought in yet. It costs over $5000 a pole to bring power in from the electric co up on the volcanoe!
The batteries are the most common over there. A old car alternator driven by a propeller on a car hub to drive the alt and your set. Only need a fireplace then it gets really cold up on the volcanoe..