We just completed a week at Big Bend National Park. We have a 12 volt golf cart
battery with 155 amps available, and two 90 watt
solar panels. Our rooftop panel provided a few amps but our movable panel provided most of the amps because we could point it toward the low sun. Each day when we returned to the camper the
battery was fully charged even though we used the
propane heater/fan a lot and also a CPAP machine. Happy with our larger battery and
solar panels.