Solar Payback Period Calculator
Estimate how many years a rooftop solar PV system takes to pay for itself, plus its 10-year and 25-year net benefit. Enter the installed cost after rebates, annual generation, how much you use yourself and your import and feed-in electricity prices — a browser-only simple-payback estimate.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the system cost in dollars after any rebates or incentives.
- Enter the annual energy the system produces in kWh per year (from a quote or a solar-output estimate).
- Set the self-consumption fraction (0–1) — the share of generation you use on-site rather than export (0.5 by default).
- Enter your electricity import price ($/kWh) and feed-in tariff ($/kWh), then read the payback period and net benefits.
How it works
Solar saves you money two ways: energy you use yourself avoids buying grid power at the import price, and surplus energy you export earns the feed-in tariff. Because self-used energy is usually worth much more than exported energy, the tool blends the two by your self-consumption fraction: blended value = self × import price + (1 − self) × feed-in. Annual saving = annual production × blended value, and simple payback = system cost ÷ annual saving. Net benefit over a period = annual saving × years − system cost. This is a simple (undiscounted) payback — it doesn't model price inflation, panel degradation, inverter replacement or the time-value of money, so treat it as a first-pass guide.
Worked example
Worked example. A $6,000 system (after rebates) producing 9,000 kWh/yr, with 50% self-consumption, a $0.30/kWh import price and a $0.05/kWh feed-in tariff: blended value = 0.5×$0.30 + 0.5×$0.05 = $0.175/kWh. Annual saving = 9,000 × $0.175 = $1,575.00. Payback = $6,000 ÷ $1,575 = 3.81 years. Over 25 years the net benefit is $1,575×25 − $6,000 = $33,375.00.
Common mistakes
- Valuing all generation at the feed-in tariff — energy you use yourself is worth the (much higher) import price you avoid, so self-consumption dominates the savings.
- Using the sticker price instead of the cost after rebates — payback should be based on what you actually pay out of pocket.
- Treating simple payback as the whole story — it ignores electricity-price inflation, panel degradation and inverter replacement, so a full net-present-value analysis may differ.
Frequently asked questions
What is a typical solar payback period?
For many homes it lands somewhere around 3–7 years depending on system cost, sunlight, how much you use yourself and local tariffs. Higher self-consumption and higher import prices shorten it; a low feed-in tariff with lots of export lengthens it.
Why does self-consumption matter so much?
Energy you use on-site offsets the full retail import price (often $0.25–$0.40/kWh), while exported energy usually earns only a small feed-in tariff (often $0.03–$0.10/kWh). Using more of your generation — by shifting loads to daytime or adding a battery — is the biggest lever on payback.
Does this account for rising electricity prices or panel ageing?
No — this is a simple payback that holds prices and output constant. In practice rising import prices shorten payback while panel degradation (~0.5% per year) and inverter replacement work against it; a net-present-value model captures those and the time-value of money.
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- Electricity Cost Calculator
- Solar Panel Count Calculator
- Battery Bank Size Calculator
- Solar Irradiance to kWh Calculator
- Inverter Sizing Calculator
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