A little window unit could possibly work for a small area of the house like the bedrooms. The central AC has been keeping it at 72-73° and RH of 38-40%. Recently now, the diesel prime set hasn't run for three days and the AC is still going around the clock. But the ambient air has less humidity even though the temp is 85-87°. It's been cooler at night so the compressor doesn't run then, and only the air handler keeps going, which doesn't draw much power. The compressor runs during the day, but the solar and wind power runs it fine with the conditions we've been having.
I'm still learning about all this - we never had AC before. But what I've learned so far is that it can keep the whole house real comfortable just on solar and wind during hot but not real humid weather. If the temp goes into the 90's and the humidity goes up the conditions in the house don't change, but then the diesel prime set is required to keep the batteries from getting dead at night.
After this summer I'll have a better idea of how much it really costs in diesel fuel to run the AC all the time - the hottest part of summer is yet to come. But my gut feeling is that it's not very much. I'm thinking that we're running our AC on off-grid power for probably less money (out-of-pocket) than somebody who lives in California would have to pay for grid power on their "tier" pricing system they got there. The investment we would have to make in solar power and batteries to run it just on RE power would be prohibitive. Running it with our gas genset would also be quite expensive - the diesel burns about half the fuel per kWh that the gas set burns. And off-road dyed red diesel fuel is really cheap right now (cheaper than gasoline by 30 cents/gallon).
So I'll know more at the end of July than I do now about how much it's going to cost. But we sure like the AC