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Solar & Wind ROI / Payback Calculator

Work out how many years a solar or wind system takes to pay for itself in avoided electricity costs, from total system cost, expected annual generation, and your electricity price.

Simple payback period8.9 years
Annual savings$900

How to measure your inputs

  • System cost: total installed cost, minus any rebates or incentives already applied.
  • Annual generation: from the Solar Array or Wind Output calculators above, or an installer's site-specific estimate.
  • Electricity price: your current utility rate per kWh, from a recent bill.

Methodology

Simple payback: years = system cost ÷ (annual generation kWh × electricity price per kWh). A standard, widely quoted metric for residential/small-scale renewable systems, deliberately not a discounted-cashflow model that would need an assumed discount rate this tool has no reliable way to source.

Reading a simple payback number correctly

Simple payback vs. a full financial model

This calculator gives simple payback — system cost divided by annual savings — which answers "how many years until the system has paid for itself in avoided electricity costs." It deliberately doesn’t model financing costs, electricity price inflation, or a discount rate, since those need assumptions this tool has no reliable way to source; simple payback is still the number most commonly quoted for residential-scale systems, so it’s a genuinely useful first check.

Why electricity price inflation usually helps you, not hurts you

This calculator uses today’s electricity price throughout, which is actually the conservative assumption — electricity prices have historically trended upward over time in most markets, which would make real payback faster than this simple estimate, not slower. If prices fall or stay flat, actual payback would be close to this estimate or slightly longer.

What a good payback period looks like

There’s no universal "good" number — it depends on system lifespan (solar panels commonly carry 25-year warranties, so a 6-8 year payback leaves many years of near-free generation afterward) and your own financial planning horizon. Compare payback period against expected system lifespan, not against an arbitrary target.

Frequently asked questions

What's the difference between simple payback and ROI?

Simple payback tells you how many years until the system breaks even. ROI (return on investment) is typically expressed as a percentage return over a specific period or the system’s lifetime, and can account for savings that continue well past the payback point — a system with an 8-year payback and a 25-year lifespan has 17 years of pure savings after breakeven, which simple payback alone doesn’t show.

Does this include government incentives or rebates?

Not automatically — subtract any rebate or incentive from your system cost figure before entering it, since that directly reduces the amount that needs to be paid back through savings.

Should I use my current electricity price or a future projection?

Current price is the safer, more conservative choice, since it doesn’t rely on a speculative projection. Since electricity prices have historically trended upward in most markets, using today’s price tends to slightly overestimate payback time rather than underestimate it.

What counts as a good payback period for a solar or wind system?

There’s no fixed answer — compare the payback period to the system’s expected lifespan (often 20-25+ years for solar panels). A shorter payback relative to lifespan means more years of essentially free generation afterward.