I currently use a backup generator to handle power outages. The plan is to take everything totally off-grid, but I probably won't do that until I expand and build my new systems, probably next year.

You can generate and store adequate electricity for the inflation fan with a small solar kit and deep cycle battery(ies), since the fan only uses around 40 watts iirc. It's also possible to rig a very small turbine to trickle charge the battery(ies).

If you want to power air pumps/water pumps, that'll increase your electricity needs a little bit, but there are still relatively cheap solar/wind systems that can provide more than enough juice.

I also think it's wise to choose your fish type and stocking density with an eye toward a worst-case scenario. It's possible to raise a lot of tilapia at a low enough density that they can thrive without aeration (or even filtration), so a large enough system of that type could supply you with all the meat you want without having to worry about catastrophic suffocation from electrical failures. If that's the route you go, I'd suggest putting a few apex predators like bass in there to eliminate the possibility of the tilapia overproducing and getting too densely populated.