Size a residential solar + storage system correctly for economics under California's NEM 3.0 / Net Billing Tariff

Steps

1. Confirm the applicable tariff is CPUC's Net Billing Tariff ('NEM 3.0' is the informal industry name) — applies to all new PG&E/SCE/SDG&E interconnection applications
2. Note the NEM 2.0 grandfathering window is closed: April 15, 2026 was the final deadline to reach Permission to Operate on legacy NEM 2.0 — any new application today is on Net Billing Tariff terms
3. Model export compensation using the time-varying avoided-cost rates rather than a flat retail-rate NEM 2.0-style assumption, since export value drops sharply outside peak hours
4. Recognize that most system value under Net Billing comes from self-consumption and shifting exports into the evening peak window (roughly 6-9pm) — battery storage captures this value that solar-only systems cannot
5. Size the battery around the household's evening load and desired backup needs rather than defaulting to a fixed ratio, since Net Billing Tariff economics are storage-driven rather than export-driven
6. Reflect realistic payback expectations in the proposal (commonly ~8-10 years solar-only vs ~7-8 years with storage under current tariff modeling) rather than pre-NEM-3.0 payback figures