Estimate solar-battery payback from battery cost, annual savings, usable capacity, and electricity-price assumptions.
E.g., Tesla Powerwall 2/3 (13.5 kWh)
Full hardware & installation price
Grid import cost
Solar export credit
Days fully cycled
Without a battery, excess daytime solar doesn't vanish — it exports to the grid for a feed-in tariff. Therefore, a battery's genuine value per kWh is the spread ($/kWh Retail minus $/kWh Feed-in), not the full retail cost.
Estimated Payback Period
9.6 Years
Net cost $10,103 ÷ Annual saving $1,053
Federal Rebate
$3,397
25% upfront discount
Net Cost Out-of-Pocket
$10,103
After STC point-of-sale deduction
Annual Bill Savings
$1,053
At 300 cycles / year
Value Per kWh Shifted
$0.26/kWh
Retail spread over feed-in
1st Year ROI
10.4%
10-Year Total
$10,530
20-Year Total
$21,060
At 9.6 years, this payback is on the longer side relative to typical battery warranties (10-15 years) — check whether your usage pattern (cycle days/year) or a smaller, better-matched battery size would improve the numbers.
From 1 May 2026, the Australian federal Cheaper Home Batteries Program utilizes a tiered STC Factor schedule to discourage oversized residential storage while maximizing support for standard 10–14 kWh systems:
100%
Base rate: 6.8 STCs / kWh (~$252/kWh rebate)
60%
60% of base rate: 4.08 STCs / kWh
15%
15% of base rate: 1.02 STCs / kWh
$0
No additional federal subsidy
Disclaimer: This tool provides informational results only and should not be used as professional advice.
The Solar Battery Payback Calculator estimates simple payback by comparing battery cost with annual savings.
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This is a planning estimate, not a guarantee of bill reduction or investment return.
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