OK, since you asked and I will apologize for my snarkiness, here is a bit of electricity 101:
The basic relationships are:
Watts are a measure of the rate of production of energy. Watts are volts times amps. AC shore power is 110-120v and DC battery power is 12V. So 100 watts AC is a little less than 1 amp and 100 watts DC is bit more than 8 amps.
Watt hours are a measure of total energy.
You can convert DC to AC using an inverter. But it takes about 10 amps DC (allowing for efficiency losses) to make 1 amp of AC.
With that electricity background maybe we can have a conversation. You said that power is expensive in the Bahamas and you run your generator to make your own. None of this has anything to do with your DC needs.
Let's assume that the incremental costs (ignoring capital costs and depreciation) of running your generator are maintenance and fuel. I will bet that the incremental costs are at least $.50 per KW. Fuel alone is probably more than half of that. Small generators are very inefficient and fuel costs in the Bahamas are high.