Solar Battery Payback Calculator
Estimate whether adding battery storage to your solar system pays off — critical for NEM 3.0 states like California where export credits are low.
How this calculator works
- Estimate whether a home battery pays off by comparing its annual arbitrage value (shifting cheap solar to expensive evening hours) against its installed cost.
- Enter battery capacity, installed cost, your electricity rate, and your export credit. The calculator models daily shifting of 60% of capacity and returns annual savings and battery payback.
- The key insight: in 1:1 net metering states the spread is near zero (battery = backup only), while in NEM 3.0 states it is huge (battery = smart investment).
Disclaimer: All figures are estimates based on public 2026 data (EIA, NREL PVWatts, DSIRE) and your inputs — not a quote, tax advice, or financial advice. The federal residential solar credit (Section 25D) expired December 31, 2025. Verify with your utility, a licensed installer, and a tax professional before signing anything.
Example scenarios
CA NEM 3.0: 33¢ rate, 5¢ export — large spread, battery pays.
1:1 metering state: 30¢ rate, 30¢ export — no spread, backup only.
Data & algorithm
- Daily shifted kWh = battery capacity × 0.6.
- Annual arbitrage = daily shifted kWh × 365 × (rate − export credit).
- Battery payback = installed cost ÷ annual arbitrage.
Official data sources
- Battery pricing: Tesla Powerwall 3 / Enphase IQ 5P 2026 street prices. Export rates: state net metering tariffs.
All figures dated 2026. Incentives and rates change — verify current values with your utility and the administering authority before making decisions.
Frequently asked questions
When is a solar battery worth it in 2026?
In net-billing states (CA, NV, AZ, HI) where exports are cheap — arbitrage payback often 6–9 years. In full-retail 1:1 states, it is mainly backup power.
How much does a Tesla Powerwall cost?
Roughly $11,500 installed for a 13.5 kWh Powerwall 3 before incentives like California SGIP.