California NEM 3.0 solar and battery payback calculator: Avoided cost analysis

What NEM 3.0 changed — and what it didn't

California's Net Billing Tariff (NBT), commonly referred to as NEM 3.0, took effect April 15, 2023 for all new solar applications. The change reduced export compensation from full retail rate credits (NEM 2.0's ~$0.27–$0.32/kWh in PG&E territory) to "Avoided Cost Calculator" rates, which average approximately $0.05–$0.08/kWh.

What did not change: solar power you consume directly in your home still offsets retail electricity at full value ($0.27–$0.47/kWh depending on TOU tier and utility). The economic revolution is in export compensation — power you send back to the grid is now worth 75–80% less than power you self-consume.

For comprehensive home energy decision-making, see our high-efficiency home infrastructure and resilience guide.

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The self-consumption arbitrage model

The fundamental NEM 3.0 economics are driven by the self-consumption ratio:

$$\text{Annual Solar Value} = (E_{\text{self}} \times R_{\text{retail}}) + (E_{\text{export}} \times R_{\text{avoided}})$$

Where:

• $E_{\text{self}}$: kWh consumed directly from solar
• $R_{\text{retail}}$: Your retail electricity rate ($0.27–$0.47/kWh in CA)
• $E_{\text{export}}$: kWh exported to grid
• $R_{\text{avoided}}$: NEM 3.0 avoided cost rate (~$0.05–$0.08/kWh)

For a 7.5 kW system generating 11,000 kWh/year in Southern California:

Battery storage recovers approximately 93% of the value lost to NEM 3.0 export rate reduction.

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Payback period comparison: NEM 2.0 vs NEM 3.0

Battery sizing guidance: The economically optimal battery capacity under NEM 3.0 captures daytime solar production that would otherwise be exported at low avoided cost rates, storing it for evening on-peak consumption (typically 4–9 PM when TOU rates peak at $0.40–$0.55/kWh in PG&E/SCE/SDG&E territory).

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SGIP battery incentive — the California offset

California's Self-Generation Incentive Program (SGIP) provides direct rebates for battery storage, partially offsetting NEM 3.0's economic impact:

• Equity tier: $1,000/kWh (income-qualified customers in high fire-risk or disadvantaged communities)
• Equity resiliency tier: $1,000/kWh (for customers on medical baseline or in Tier 3+ HFTD)
• General market: $150–$250/kWh (for standard residential batteries)

A 13.5 kWh Tesla Powerwall at $250/kWh SGIP = $3,375 in rebates, reducing net battery cost to approximately $6,500–$8,500 after incentives.

Use the Solar ROI Calculator to model your specific NEM 3.0 self-consumption ratio, battery size, and TOU rate schedule for a personalized payback analysis.