Global solar decision tool
Solar Savings &
Payback Calculator
Estimate first-year savings, payback time and 10, 20 and 25-year returns—using your own quote, electricity rate, export credit and solar production.
Electricity prices, export compensation and incentives vary by utility and jurisdiction. This tool does not invent a global average—enter values from your own bill, quote and official local program. New to the calculation? Read the step-by-step solar payback formula and editable example.
Your numbers, not national averages
Calculate solar savings and payback
Enter figures from your installer quote, electricity bill and a location-specific production estimate.
Currency and system
No exchange-rate conversion is applied.
Production and energy value
Use your own utility and location values.
Long-term assumptions
Set either value to 0 for a flat projection.
Every step is visible
How the calculation works
System capacity is shown for context and yield checking. Annual production drives the savings model because location, orientation, shade and system losses determine output.
Net upfront cost
installation cost − verified rebateThe rebate is capped at the installation cost; no negative upfront cost is created.
Generation in year y
year 1 kWh × (1 − degradation)^(y−1)Set degradation to zero if you do not want production to decline in the projection.
Savings in year y
self-used kWh × retail rate + exported kWh × export creditThe retail rate grows by your tariff-increase input; export credit stays flat.
Payback and simple ROI
ROI = 25-year net savings ÷ net cost × 100Payback is interpolated within the year when cumulative savings recover the net cost.
Official production reference
Start with a location-specific energy estimate.
NREL’s PVWatts® Calculator estimates the energy production of grid-connected photovoltaic systems throughout the world. Use its annual kWh result here, then compare it with a qualified installer’s site-specific estimate.
Open the official PVWatts Calculator ↗PVWatts is a modelling tool, not a generation or financial guarantee.Read before deciding
What this estimate does not include
A clear boundary is more useful than false precision. Add these items to your own decision process where they apply.
Loan interest, lease or power-purchase agreement terms, taxes and opportunity cost.
Battery operation, inverter replacement, maintenance, cleaning, insurance and downtime.
Fixed or demand charges, net-metering caps, time-of-use rates and future export-policy changes.
Weather, shade, soiling, clipping, outages, roof orientation and equipment performance.
This free calculator provides an educational estimate, not financial, engineering, tax or legal advice and not a savings guarantee. Verify all inputs and decisions with your utility, official incentive authority, qualified solar professional and financial adviser where appropriate.
Frequently asked questions
Solar payback, explained
How is solar payback calculated?+
The calculator subtracts your verified rebate or subsidy from the installation cost, then adds each year's avoided electricity cost and export credit. Payback is the point when those cumulative savings equal the net upfront cost.
Why does self-consumption affect solar savings?+
Solar used on-site avoids the retail electricity price, while exported electricity may receive a different credit. Separating the two prevents the calculator from valuing every generated kWh at the same rate.
Where can I estimate yearly solar production?+
Use a qualified site assessment or the official PVWatts Calculator. PVWatts estimates grid-connected PV energy production worldwide using location and system inputs; actual output can still vary with weather, shade, equipment and maintenance.
Does this calculator include batteries, loans or maintenance?+
No. It is a simple cash-purchase projection. It does not model battery dispatch, finance interest, taxes, maintenance, inverter replacement, insurance, demand charges or changing export rules unless you account for them in your own cost inputs.
Are the currency options exchange rates?+
No. Currency selection only formats the figures. Keep installation cost, rebate, electricity price and export credit in the same currency.
Is the result a quote or savings guarantee?+
No. The result is an educational estimate based entirely on the values and assumptions you enter. Verify system design, incentives, tariffs, export rules and financial terms with qualified local professionals and official authorities.