I use this guy to supplement my solar panels in the winter. It does 30a, I haven't had an issue running the microwave and ac off it simultaneously. I just finished my second year with it, so far it's just needed an oil change.
I never did the math that far down. There aren't many weeks where I needed to run it every day. The lower your draw the better has been my rule of thumb.
I have a couple jackery batteries that I keep topped off in addition to my solar system. The jackery stuff has it's own solar panels that I can run through a window in fair weather. That stuff, $/kWh, is the ay cheaper. But of course it has a huge up front investment.