Which is true. But it's a rug pull for people who spent money on their panels expecting an RoI. Were existing installations grandfathered in?

Yes, existing installations get 20 years of grandfathered rates [1].

Which makes it more of a ladder pull than a rug pull...

[1] https://www.sce.com/clean-energy-efficiency/solar-generating...

That's fine. If we have enough X then stop paying people to build more X.

Late thought: we continue to reward those who built more X when we needed more X, and that's fine too.

The first round of people paid way more for their solar panels though, and those higher prices helped bootstrap the industry. Should people who paid much less for panels get the same reward? I'm having trouble getting outraged about this, it seems to be incentives working exactly as they should.

I agree, and maybe my "ladder pull" comment comes off as too negative. Most early solar buyers were either in it for environmental reasons or for a modest return on investment. I don't think many were expecting a windfall.

Solar has become all about ROI these days just like home ownership has become an investment.