One Year of NEM 3.0 in California: Battery Adoption Soars as Export Rates Plummet

One year after California's NEM 3.0 net billing tariff took full effect, the data reveals a dramatic reshaping of residential solar economics in the state. Export compensation rates under the avoided cost calculator average $0.05–$0.08 per kWh, down roughly 75% from the flat retail-rate credits homeowners received under NEM 2.0. The practical result: a solar-only system without storage now has a simple payback period of 12–15 years in California versus 7–9 years previously. However, the market has adapted sharply. Battery storage attachment rates on new residential solar installations climbed to 74% statewide by Q4 2025, up from approximately 15% before the transition, representing a 400% increase. The average system now pairs a 7–10 kW array with a 10–13 kWh battery, primarily to maximize self-consumption during peak-rate evening hours under time-of-use tariffs. For existing NEM 2.0 customers, grandfathering protections remain in place through April 2028, making system expansions a near-term priority. Financial advisors and solar contractors recommend homeowners on NEM 2.0 consider adding battery storage now to extend grandfathered status. Homeowners on NEM 3.0 should program battery charge windows between 9 AM and 3 PM to capture low-cost solar and discharge during peak TOU periods of 4–9 PM when rates can exceed $0.45 per kWh.