Is net return all that matters? Seems like with increasing heat waves, power outages etc, being able to generate and store your own electricity has value from a resiliency standpoint.

Note that merely having solar panels on your house doesn't automatically let you run your house off of the panels in the event that the grid goes down. Firstly, if you're connected to the grid, then a single house trying to push power into a downed grid would be like trying to refill the ocean with a super soaker. Even with lots of houses doing it, the frequency would be wildly unstable at best and cause damage to equipment. Secondly, it poses dangers for lineworkers who are probably trying to resolve the outage, by putting surprise voltage into wires.

It's certainly possible to have a solar installation that does let you disconnect from the grid, but it requires extra hardware (including a battery backup).

Exactly right. Typical solar installations keep you on the grid. And when the grid goes out, so do you.

To become grid-independent adds substantial expense. Having your own battery adds another $10-20k, along with whatever costs are associated with switching the grid.

Also, being off-grid is actually illegal in some places.

Why would it be illegal? Safety concerns? (E.g. freezing in Alaskan winter)

Utilities and governments tend to have close relationships.

Governments want utilities to continue working at reasonable prices, so they regulate utilities heavily. In exchange, utilities get protection against competition. This is true in many countries.

Specifically around solar, there's a concept called "utility death spiral" where more and more people opt out of the grid, causing the grid to be unmaintainably expensive. This the dream that solar conpanies tell their investors.

Power companies would of course want protection from the utility death spiral, and can often get it.

Disconnection isn't always illegal. Another form this can take is "all houses have to pay a grid fee, whether or not they are connected".

I'm not sure what kinds of hardware you guys have seen or been marketed. But from my pov, these are all pretty standard features of most hybrid inverters and come out of the box. The only extra expense to not be grid tied is needing a battery and maybe a tiny amount of extra electrical wiring. It wasn't even a question that popped up during my build.

Then again, we regularly have huge rolling blackouts here so we need the inverter to be a giant UPS for the house and be able to use solar and grid at the same time.

What's the math if we see annual electricity price increases? we've seen 2 hikes of 10-20% in the last 18 months here in Florida. Making me consider solar sooner rather than later.

If the savings is $2677 on year 8 (first year of profits after paying off the initial investment) and then increases 10% every year after that, the net return is $33675. This works out to an annual return of 7%, a considerable improvement! The same calculation with annual rate increases of 20% yields a net return of $53002 and an annual return of 9%.

I agree its a big assumption to assume that electricity prices will stay the same, my assumption is that electricity price increases will significantly outpace inflation.

Also there is a question if electricity produced by panels will match the peak demand or in general is utilized. Scenario where solar is overbuild and thus power generated by it has near zero price for large part of the day might happen.