What inputs do I need?

System cost, incentives, annual kWh, your retail electricity price, export price, and the fraction of energy you self-consume. Optionally set degradation, price inflation, O&M, inverter replacement, and discount rate.

What’s the difference between simple and discounted payback?

Simple payback ignores the time value of money. Discounted payback uses your discount rate to value future cash flows less than today’s money.

Is any data uploaded?

No. Everything runs locally in your browser for privacy.

Solar Payback Calculator — Time to Break Even

Friendly, awareness-level economics. Private by design — runs locally in your browser.

Inputs

Currency System cost (incl. install) Incentive type Incentive value

Annual generation (kWh/year) Self-consumption (%) Retail price (per kWh) Export price (per kWh)

Assumptions (optional)

Panel degradation (%/year) Electricity price inflation (%/year) Annual O&M (currency) Inverter replacement year optional Inverter replacement cost Discount rate (%/year) Analysis years

Awareness-level estimator. Real bills and incentives vary by utility, tariff, and policy. Edit inputs to match your context.

Results

How This Solar Payback Calculator Works (and What the Numbers Mean)

This tool estimates how long it takes a solar PV system to “pay for itself” in bill savings and export income. It starts from your net upfront cost (system price minus incentives), then projects year-by-year cash flows based on annual kWh, your self-consumption rate, the retail price you avoid paying for self-used energy, and the export price you receive for surplus sent to the grid. Optional assumptions let you reflect real-world details: panel degradation (slightly lowers kWh each year), electricity price inflation (raises the value of savings), O&M costs, inverter replacement, and a discount rate to compute NPV and discounted payback.

Cash Flow Basics

Each year’s savings are split: Self-consumed kWh × retail price plus exported kWh × export price. If you self-consume 50% of generation, half your kWh offset your retail rate and the rest earn the export rate. The calculator tracks cumulative cash flow and reports the first year when cumulative cash flow turns positive (simple payback). If you set a discount rate, it also shows discounted payback, NPV, and IRR over the analysis period.

What to Adjust

Self-consumption: Higher self-use typically shortens payback when retail prices exceed export tariffs.
Export price: Tariffs vary widely. Use your local rate for realism.
Degradation & inflation: Small yearly changes compound over time; tweak to test sensitivity.
Costs: Add O&M and a one-off inverter replacement if applicable to your system.

Note: This is a planning tool, not financial advice. Policies and tariffs change; always confirm details with your installer or utility.