Battery Storage Calculator

This calculator models home battery storage savings over 15 years. For time-of-use (TOU) rate structures, savings come from charging the battery at off-peak rates and discharging during on-peak hours (rate arbitrage). For flat-rate plans with solar, the battery captures excess solar generation for later self-consumption instead of exporting at a lower net metering rate. Battery capacity degrades annually (default 3%/year), while utility rates escalate at 3%/year. Note on incentives: the 30% federal Residential Clean Energy Credit (25D) that covered battery storage ended December 31, 2025 — installations completed after that date do not qualify, so the federal credit toggle is off by default and should only be enabled for systems installed by the deadline. State incentives (e.g., California's SGIP) are governed separately, remain available in several states, and are applied when enabled. Net system cost equals the gross cost minus all applicable incentives. The payback period is the year when cumulative net savings first exceed zero.