I have a project in work, to build an inverter generator. So far I have a 12 hp Kohler pullyed to a 24v alternator so that at 1800 rpm, the alt is turning 5,000 rpm to power 4 6v 220ah batteries in series. I currently have a small 24v inverter, but once I rig up a governor, I'll pick up a much larger inverter. I'll also add a small solar panel to keep those bats topped off.
I have two LIron batteries already... Another two this year. I will continue to introduce them in a staggered fashion, across several years so they don't all go bad at the same time, when they finally do. Unfortunately, the solar side is not quite done... and the jenny I have is the 8500W contractor generator I have had for years. It does not have the sensing to turn on when the batteries holler for it, but I have rigged it to turn off when the batteries are charged (I can send signal to a switch that uses the natural grounding wire that normally shuts it off).
So right now I have to manually start it, and no option but to watch the fuel - But it's better than nothing.
With four batteries I should be pretty set - with 6 for sure. Now I am just waiting for a failover jenny to come down the river, and figure to get the 4 solar panels I have mounted up next spring.
You might get a kick out of what I am doing with the panels - Petal style... Automatically deploy from protected storage like the petals of a flower - And retract at night or during storms... Don't have that part all the way figured out... I want it to deploy when there is enough light to make it worthwhile, and otherwise default to stored and shut off. Six positions, one being the storage box...
Also want it to track the sun - That would matter here in the winter. Both vertical and horizontal axis. BUT, that wound up scrap. I was using an antenna rotor (from my big Moonraker beam antenna) and it just didn't have the poop. So for now I just dummied a bushing in where it goes so I can finish what I am doing... But I have no idea what the rotor will be now, and have not even begun working on the logic for automating (though probably Raspberry Pi).