Solar Battery Payback Calculator
Estimate annual delivered battery energy, avoided grid cost, net annual savings and simple payback from battery capacity, cycling and electricity values.
Default project preview
13.5 years
Delivered energy per cycle
11.18 kWh
Annual delivered energy
3,353 kWh
Avoided grid value
$1,073.09
Charging energy value
$291.60
Calculator
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Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Installed battery cost
Enter this project assumption in a unitless value. The current imperial default is 9500. Minimum: 0.
Nominal battery capacity
Enter this project assumption in kWh. The current imperial default is 13.5 kWh.
Usable capacity
Enter this project assumption in %. The current imperial default is 90 %. Minimum: 1. Maximum: 100.
Round-trip efficiency
Enter this project assumption in %. The current imperial default is 92 %. Minimum: 1. Maximum: 100.
Equivalent cycles per year
Enter this project assumption in cycles. The current imperial default is 300 cycles. Minimum: 0.
Avoided grid energy value
Enter this project assumption in per kWh. The current imperial default is 0.32 per kWh. Minimum: 0.
Solar charging energy value
Enter this project assumption in per kWh. The current imperial default is 0.08 per kWh. Minimum: 0.
Annual maintenance allowance
Enter this project assumption in a unitless value. The current imperial default is 80. Minimum: 0.
How to read the outputs
Delivered energy per cycle
after round-trip loss. Default preview: 11.18 kWh.
Annual delivered energy
300 equivalent cycles. Default preview: 3,353 kWh.
Avoided grid value
annual delivered energy value. Default preview: $1,073.09.
Charging energy value
modeled solar opportunity cost. Default preview: $291.60.
Net annual savings
after charging value and maintenance. Default preview: $701.49.
Ten-year net position
before financing, degradation and replacement. Default preview: -$2,485.12.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Annual delivered energy = capacity × usable share × efficiency × cycles. Net savings = avoided grid value − charging-energy value − maintenance. Payback = installed cost ÷ net savings.
FAQ
Solar Battery Payback Calculator questions
Why assign a value to solar charging energy?+
Energy used to charge a battery may otherwise have been exported or used directly, so it can have an opportunity cost.
Does backup power value appear in payback?+
No. Reliability and outage resilience are personal or business values not included in the simple energy calculation.
Will battery degradation change payback?+
Yes. Declining usable capacity reduces delivered energy over time.