I think it’s more like this: Say maintenance of a grid costs $1 million/year, power generation costs another $1 million/year and people use 10 million kWh/yr at 20¢ per. Everything is balanced. Then half the people cut their usage in half. Grid maintenance still costs $1 million/year, generation dropped to $750,000, but revenue dropped to $1.5 million. They have to raise the price 16% to go back to paying for maintenance. You’re still saving money if you dropped your usage more than 16%, but those that didn’t pay the difference.

Since you generally have to be fairly well-off to afford the massive upfront labor costs involved with solar, its adoption has disproportionately raised the living expenses of the lower class.

The alternative is a base services charge, where everyone pays a flat percentage of the grid maintenance costs and then his or her usage is on top of that. No idea why it’s taking this long for PG&E to adopt that model, but adding charges for solar is a big improvement in equity.