Battery calculator
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Home Battery Storage Calculator — Is It Worth It?
Calculate the right battery storage capacity for your home, estimated cost after federal tax credit, and annual savings from storing solar energy.
✓ Updated June 2026
✓ EIA & NREL data
✓ 30% federal ITC included
10–15 kWh
Typical size
$300–800/yr
Extra savings
30%
ITC eligible
Estimate scope & data quality
This tool provides an input-driven estimate. Use the required inputs shown above and review the result limitations below.
- Data quality
- NOT_AVAILABLE
- Result limitation
- Calculator output is not a source-complete customer result.
A tariff credit is distinct from annual savings. If a result is NOT_COMPUTABLE or CONFLICT, it must not be replaced with an estimate or treated as canonical.
How to use this calculator
- Enter your average daily electricity usage in kWh (check your utility bill — divide monthly kWh by 30).
- Enter how many days of backup power you want during an outage.
- Adjust the depth of discharge — how much of the battery you're willing to use (80% is standard).
- Enter your electricity rate to calculate annual savings.
- Results show the battery capacity you need, estimated units, cost and payback period.
Frequently asked questions
Direct answers for US homeowners.
Each Tesla Powerwall 3 stores 13.5 kWh. A typical US home using 30 kWh/day would need about 2-3 Powerwalls for whole-home backup. For overnight solar storage only (storing afternoon solar for evening use), 1 Powerwall is usually sufficient.
Yes. As of 2023, standalone home battery storage systems (not just solar+battery) qualify for the 30% federal ITC under the Inflation Reduction Act, as long as the battery capacity is at least 3 kWh.
LFP (lithium iron phosphate) batteries like the Powerwall 3 last longer (4,000+ cycles), are safer, tolerate 100% discharge, and work better in heat. NMC batteries have higher energy density but degrade faster. For home storage, LFP is generally preferred.
Yes, most modern inverters are battery-ready, and AC-coupled batteries like the Powerwall can be added to any existing solar system. DC-coupled batteries require a hybrid inverter. Adding storage later typically costs 15-20% more than installing at the same time as solar.
Related guides
In-depth articles on sizing, costs, and energy decisions.