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Solar Battery Payback Calculator
Solar batteries like Tesla Powerwall, Enphase IQ, FranklinWH cost $10K-$18K installed. Payback depends on: time-of-use (TOU) arbitrage, backup value in outages, and 30% federal tax credit. This calculator models the ROI.
Payback years
14.5
Net cost after credit/rebate
$9,450
Annual benefit
$650
Federal tax credit
$4,050
15-year lifetime net (after payback)
$300
How the math works
$13,500 installed battery: $4,050 federal credit → $9,450 net. $650/yr annual benefit. Payback 14.5 years. 15-year lifetime: net $300 positive.
Pure ROI rarely drives battery purchase — comfort + resilience do. California SGIP rebate (up to $5K) is the main thing that makes batteries attractive on cost alone.
How to Use
- Enter battery installed cost, annual TOU arbitrage savings, and expected outage value.
- See net cost after tax credit and payback years.
Frequently Asked Questions
What's TOU arbitrage?
Time-of-use rate plans charge 3-5x more during peak (4-9pm) vs off-peak. Battery stores off-peak or solar electricity, discharges during peak. Annual savings $200-$600 in high-TOU markets (CA, NYC).
How much is outage protection worth?
Varies wildly. Cold-climate freeze = $5K+ pipe damage. Tropical storm outage = $300 food spoilage. Average grid outage 6-10 hrs/yr. Value $100-$500/yr typical; higher if high-outage area.
Tax credit?
30% federal IRA credit through 2032 on battery + installation. State credits vary (CA SGIP rebate up to $5K). Combined can reduce net cost 40-50%.
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