Solar Battery Storage Calculator

Battery value comes from two sources: time-of-use (TOU) rate arbitrage and backup power value during outages.

Arbitrage value: each day, the battery stores cheap off-peak (or solar-produced) electricity and discharges during peak rate hours. Daily savings = usable battery capacity × (peak rate − off-peak rate). We assume 90% depth of discharge and 365 cycles per year.

Backup value: the value of avoiding outages varies widely. We let you specify an annual figure (default $0 if you have rare outages, $100–$500 if you experience them regularly).

The battery qualifies for the 30% federal tax credit (through 2032) when paired with solar or installed standalone with at least 3 kWh capacity.

Home battery storage has become significantly more accessible since the Inflation Reduction Act extended the 30% tax credit to standalone storage. A typical Tesla Powerwall 3 or equivalent system costs $12,000–$15,000 installed; after the federal credit, that drops to about $8,400–$10,500.

The financial case for a battery depends heavily on your utility's rate structure. In California, Hawaii, and other markets with steep time-of-use spreads, batteries can capture $0.15–$0.30/kWh per cycle, paying back in 10–13 years. In simpler net metering markets, the arbitrage value is minimal because every kWh you export earns retail credit anyway.

The non-financial value matters too. Backup power during outages is increasingly relevant as climate-related grid stress grows. Batteries paired with solar provide true energy independence — you can ride through multi-day outages with continued solar charging. For some homeowners, this resilience is worth the cost regardless of the strict payback math.