Capacity is a fixed cost. Society expects five nines, so we build the grid to meet the peak hour of the peak year out of ten years. But the cost to meet that peak is amortized over all of the electricity. And because the per capita use in California is lower than most other states, the fixed cost is amortized across fewer hours. Rooftop solar decreases total retail usage. Afternoon air conditioning increases the peak. Both contribute to increasing retail rates. Importantly, wholesale rates (where the market is deregulated) have not seen the same increase that retail rates have seen.