Solar would work but maintenance is still expensive plus and many people still use generators to charge their solar battery as it isn't too efficient
Discussion
Ah, I see. One way is to run Sovran_SystemsOS on a laptop. This would give you some battery power for when the generator runs out of gas. Then you could either gracefully shut it down or do the maintaince to the generator while the battery power is used as not to interput service.
I am thinking out loud.
I think this is a better solution