> If it's the latter, then reduction of 1 kWh delivered should save them the same amount of money.
The "net metering" policy being changed isn't regarding "saving the grid the money by reducing the amount delivered to a customer." If you don't use the power from them, you don't pay for it. But this is about the utility paying the customer the retail rate for excess generation - aka paying retail rate for something that would offset a cost they'd otherwise pay wholesale rate to generate. This is about the current (not the new) system: https://news.energysage.com/net-metering-2-0-in-california-e...
It's not clear to me at all that it makes sense to compel the utility to purchase your excess power at the retail rate, if you're generating more than you can use. It also seems to gives weird incentives to size and spend on your home setup.