California had proposed a rule (NEM 3.0) that would add a grid access charge for solar, which is reasonable. However, the cost for the average solar install would be $50+/month.
The only reason why some solar customers pay zero is that they _significantly_ overproduce (export more than they use) and overproduction is compensated at the wholesale rate (typically $0.03-$0.04/kWh for PG&E), not the retail rate ($0.11-$0.45/kWh for PG&E).