Solar payback period calculator
By the SmartSolarSizer team · Published
Quick answer
Solar payback period is the number of years your savings take to repay what the system cost. Put in your price, your electricity rate and what exports earn, and the calculator gives the year you break even and what you're ahead by after 25 years. For the example homes below, with panel ageing and rising prices counted, that's about 8.7 years in New York, 9.0 in London, 4.0 in Lahore and 2.5 in Delhi after the subsidy.
Work out your solar payback
Step 1: pick the example closest to you. Step 2: change the numbers to match your quote and electricity bill. The answer updates as you type.
On your quote, e.g. 5 kW.
Enter 0 if none.
Sets how much sunshine your panels get.
From your bill. In dollars or pounds, 18 cents is 0.18 and 26p is 0.26.
With net metering, enter the same as what you pay.
Often 30–50% without a battery. More if you run big loads in the daytime.
More settings (optional)
Also raise the share you use yourself.
From your installer's quote. Leave blank to use your city.
–
More results and year-by-year table
Simple payback ignores panel ageing and price rises. Discounted payback counts future savings at less than today's money.
| Year | Output vs new | Price per kWh | Savings | Running total |
|---|
How the calculator works
Each year it multiplies the solar your panels make by what each unit is worth to you, then adds that to a running total that starts at minus the cost. The year the total passes zero is your payback.
savings in a year = solar made × (share used at home × grid price + share exported × export rate)
- Solar made comes from the European Commission's PVGIS data for the city you pick, for panels at the best tilt with 14% system losses. If your installer's quote or monitoring app gives a yearly figure, enter it under "More settings" instead.
- Panel ageing follows the Jinko Tiger Neo warranty: 99% of new output in year 1, then 0.4 points less each year (Jinko datasheet).
- Prices rise by the rate you set. Both the grid price and the export rate rise with it, which suits net metering; if your export rate is fixed, lower the rise a little.
- Simple payback is cost ÷ first-year savings, with no ageing or price rise. Discounted payback counts future savings at less than today's money, at the rate you choose.
For the full method, with every step worked by hand, read our guide to the solar panel payback period.
Solar payback in 2026: four example homes
These are the calculator's four starting examples. Click one above to load it, then change anything that's different for you.
| Example home | Cost after support | Solar a year | Savings in year 1 | Simple payback | With ageing and price rises | Ahead after 25 years |
|---|---|---|---|---|---|---|
| US, New York, 6 kW | $14,940 | 8,432 kWh | $1,534 | 9.7 years | 8.7 years | $41,647 |
| UK, London, 4.5 kW | £7,600 | 4,599 kWh | £766 | 9.9 years | 9.0 years | £18,544 |
| Pakistan, Lahore, 5 kW | Rs 6,50,000 | 8,030 kWh | Rs 1,59,315 | 4.1 years | 4.0 years | Rs 47,86,230 |
| India, Delhi, 3 kW | ₹97,000 | 4,873 kWh | ₹38,982 | 2.5 years | 2.5 years | ₹12,33,163 |
Prices: US $2.49 a watt, second half of 2025 (EnergySage via Solar Power World); UK about £7,600 for 4.5 kWp (Which?); Pakistan Rs 6–7 lakh for 5 kW (Pakistan Observer); India Rs 1.5–2 lakh for 3 kW (Business Today) less the PM Surya Ghar subsidy of up to Rs 78,000 (Delhi government). Tariffs: US average 18.19¢ (EIA); UK cap 26.32p (Ofgem); Pakistan export about Rs 11 under net billing (The News). Self-use shares, the export rate assumptions and price rises outside the US are ours.
Sunshine helps: 1 kW of panels in Lahore makes about 1.6 times as much as in London. But the bigger difference is price. In Lahore the first year's savings are about 25% of what the system cost; in London they're about 10%. Cheap panels and expensive grid power make the fastest paybacks.
What changes your payback the most
Here is the Lahore example with one thing changed at a time. It shows where an hour of effort, or a better quote, pays off:
| Lahore, 5 kW: what changes | Payback | Change | Ahead after 25 years |
|---|---|---|---|
| As set (Rs 6.5 lakh, Rs 33.10, Rs 11 export, 40% self-use) | 4.0 years | – | Rs 47,86,230 |
| System costs 20% less | 3.2 years | −0.8 years | Rs 49,16,230 |
| System costs 20% more | 4.7 years | +0.7 years | Rs 46,56,230 |
| Grid price 20% higher (Rs 39.72) | 3.5 years | −0.5 years | Rs 55,11,792 |
| 70% of solar used at home | 3.0 years | −1.0 years | Rs 66,02,874 |
| 25% of solar used at home | 4.7 years | +0.7 years | Rs 38,77,909 |
| Export rate cut to Rs 5 | 4.8 years | +0.8 years | Rs 37,99,818 |
| No yearly price rise | 4.1 years | +0.1 years | Rs 31,01,873 |
| Inverter replaced in year 12 for Rs 1.5 lakh | 4.0 years | No change | Rs 46,36,230 |
Under net billing, how much solar you use yourself matters as much as the price you pay for the system. Moving the washing machine, iron, water pump and AC into the sunny hours costs nothing and shortens payback more than haggling 20% off the quote. Our net metering and net billing guide explains why exported units earn so much less.
Does a battery shorten or lengthen payback?
A battery adds cost, and it only earns its keep by letting you use solar that you'd otherwise export cheaply. In Lahore, a battery that raises self-use from 40% to 70% is worth about Rs 52,707 a year before battery losses: each unit moved from export to home use is worth Rs 22.10 more. It shortens your overall payback only if it pays for itself faster than the panels do, which here means costing less than about Rs 2,10,000. A dearer battery lengthens the payback, but it can still be worth having: over its first 10 years the extra self-use is worth about Rs 5,92,641, and it keeps the lights on during load-shedding.
To test it, enter the battery price under "More settings" and raise the self-use share. Use the battery size calculator to find the size you'd need.
Is your solar payback period good?
Panels are usually warranted for 25 to 30 years, so a payback of under 10 years leaves most of their life as profit. Another way to judge it is the return on cost: what the system leaves you ahead after 25 years, as a share of what you paid. Compare that with what the same money would earn elsewhere, or use the discounted payback with your savings rate.
If your payback looks long, the usual causes are a system bigger than your daytime use, a poor export rate, or a high quote. Size the system to your loads with the solar panel and inverter calculator, which also has a Bill & Payback tab that works from your monthly bill.
What this calculator leaves out
It doesn't know your roof. PVGIS figures assume panels at the best angle facing the equator with no shade, so an east- or west-facing or shaded roof will make less. Enter your installer's yearly figure if you have one. It also doesn't model tariff slabs or time-of-use rates, changes to export rules, or financing costs. If you borrow to pay for the system, add the interest to the price.
Common questions
How do I calculate my solar payback period?
Divide what the system costs you after any subsidy by what it saves you each year. For a closer answer, allow for panels losing a little output each year and electricity prices rising, which the calculator does year by year.
What figure should I use for the share of solar I use at home?
Without a battery, homes often use around 30 to 50% of their solar themselves, more if they run big loads like an AC, pump or washing machine in daytime. With full net metering it doesn't matter much, because exports are worth the same as the units you use.
Why does my installer quote a shorter payback?
Quotes often assume every unit is worth the full grid price, a high yearly price rise, and the best possible output. Ask what export rate, price rise and yearly kWh they used, and enter the same figures here to compare.
What does the status label mean?
It is our own rough guide: Good means the system pays for itself in 8 years or less, Fair 8 to 14 years, and Weak longer than that. Panels usually last 25 years or more.
Should I include the cost of replacing the inverter?
If your inverter's warranty is 10 to 12 years, yes: set aside its replacement cost in year 11 or 12. It usually doesn't change the payback year much, but it reduces what you're ahead by after 25 years.
My city isn't in the list. What should I pick?
Pick the city with the most similar sunshine, or better, enter your own yearly output in kWh under More settings. You can get one for any address from the European Commission's free PVGIS tool.
Sources
The example prices and tariffs come from these sources, checked on 30 October 2026. Where we had to assume something, the text says so.
- PVGIS 5.3, European Commission
- Solar Power World: EnergySage H2 2025 price report
- IRS: clean energy credit changes (Aug 2025)
- EIA: average retail price of electricity, Table 5.3
- Which?: solar panel costs (Aug 2026)
- Ofgem: price cap Oct–Dec 2026
- Pakistan Observer: solar installation costs (Apr 2025)
- Pakistan Observer: NEPRA FY2026 base tariffs
- The News: net billing in Pakistan (Feb 2026)
- Delhi government: PM Surya Ghar subsidy
- Business Today: PM Surya Ghar costs (Jul 2026)
- Jinko Tiger Neo datasheet
- 10 CFR 436.23: simple payback
- ACCA: discounted payback
Not sure what size system you need?
Add your appliances to the full calculator for the panels, inverter and battery, then come back with the quote.
Open the full calculator →