> If there were a carbon tax, net metering of retail solar would still be unsustainable, just with different price points.

If there was a (correctly priced) carbon tax, I wouldn't be making this argument. Clean forms of energy would naturally win in the market, because they are in fact much cheaper when you take the long-term consequences of dirty energy into account.

We don't do that, so we need to subsidize clean energy production instead. The free grid connection is a reward for performing a social good.

And, it is not "unfair" to make PG&E pay extra for clean energy when we let them release carbon into the atmosphere for free.

That isn't the situation today. The decision is between two clean energy sources, where one is 10x the cost of the other.

Net metering meant pge had to buy residentially generated power for 40 cents instead of industrial solar for 4 cents.

...does California already have enough industrial solar to power the entire state? I didn't realize that, that changes things significantly.

Yes, it has to turn off industrial solar production on sunny days. Less frequently, it has negative wholesale prices where it pays other states to take the excess power.

This is exactly why they got rid of net metering

Yeah this is exactly why the new version of the policy (attempts to) incentivize storage in addition to solar, because that makes the excess solar power more useful, by allowing it to be time-shifted to times when there is a dearth instead of an excess (ie. when the sun goes down). The big subsidy of net metering for stand-alone residential solar is no longer beneficial; there are better things for the system at large to be spending its resources on, like storage, and also transmission and distribution improvements.