Solar panel payback period: how long it takes and how to calculate yours

By the SmartSolarSizer team · Published 10 August 2026 · Updated 9 November 2026

Quick answer

Most home solar systems pay for themselves in about 2 to 10 years, and the biggest factor is what grid electricity costs where you live. In our 2026 worked examples, a 6 kW system in New York pays back in 9.7 years, a 4.5 kWp system in London in 9.9 years, a 5 kW system in Lahore in 3.1–4.1 years and a 3 kW system in Delhi in 1.8–3.1 years after the PM Surya Ghar subsidy. Panels carry 25-year-plus performance warranties, so most of their working life comes after payback.

The formula is simple: payback period = net cost ÷ yearly savings. The savings side is where most estimates go wrong, because a unit you use yourself is often worth two or three times a unit you export. To skip the arithmetic, our solar payback calculator runs it year by year with your own quote and tariff.

The solar payback formula

payback (years) = net system cost ÷ yearly savings yearly savings = units used at home × import price + units exported × export rate

That's simple payback: the years it takes for savings to equal what you spent, with no discounting. US federal energy rules define it the same way (10 CFR 436.23). It's a good first test. The sections below add the three things that move it: panel ageing, electricity prices, and the value of money over time.

Step 1: the net cost

Start with the installed price, then subtract any grant, subsidy or tax credit you'll actually receive. Typical prices we found:

US: $2.49 a watt in the second half of 2025, from EnergySage's marketplace report (Solar Power World). The 30% federal tax credit is gone for systems completed after 31 December 2025 (IRS).
UK: about £7,600 for a 4.5 kWp system (Which?).
Australia: A$5,000–6,000 for a 6.6 kW system after the STC discount, October 2026 (Solar Choice).
Pakistan: Rs 6–7 lakh for 5 kW, as reported in April 2025 (Pakistan Observer). Prices follow the dollar, so get fresh quotes.
India: about Rs 1.5–2 lakh for 3 kW (Business Today), less the PM Surya Ghar subsidy of up to Rs 78,000 (Delhi government).

Step 2: the yearly savings

First, how much the panels make. We use the European Commission's PVGIS data: 1 kW of panels makes 3.85 kWh a day on average in New York, 2.80 in London and 4.40 in Lahore. Multiply by your system size and 365.

Next, what each unit is worth. A unit your home uses saves the full import price. A unit you export earns whatever your scheme pays, which can be much less. Pakistan's new net billing pays about Rs 11 against base import rates up to Rs 41.78 (The News, Pakistan Observer), and UK export tariffs run about 1–16p against a 26.32p import cap (Which?, Ofgem). Our net metering guide covers each country's rules.

How long solar payback takes: US, UK, Pakistan and India

Example	Cost after support	Solar a year	Savings a year	Simple payback
6 kW, New York (US)	$14,940	8,432 kWh	$1,534	9.7 years
4.5 kWp, London (UK)	£7,600	4,599 kWh	£766	9.9 years
5 kW, Lahore (Pakistan)	Rs 650,000	8,030 kWh	Rs 159,315	4.1 years
3 kW, Delhi (India)	Rs 72,000–122,000	4,873 kWh	Rs 38,982	1.8–3.1 years

Assumptions, all ours: every New York unit valued at the US average residential price for January–August 2026, 18.19¢ (EIA, preliminary); use your own utility's rate, which may be higher or lower; London uses half its solar at 26.32p and exports half at 7p, toward the low end of SEG rates; Lahore uses 40% at the Rs 33.10 slab rate and exports 60% at Rs 11; Delhi uses an example tariff of Rs 8 a unit, as tariffs vary by state. Change them to your own figures.

The Lahore line shows why self-use matters so much now. Raise the share used at home from 40% to 70%, by running the AC, pump and laundry while the sun is up, and the simple payback falls from 4.1 to 3.1 years.

Step 3: allow for panel ageing and rising prices

Panels lose a little output every year. NREL's review of more than 2,000 measured rates found a median loss of 0.5% a year (NREL). A modern Jinko Tiger Neo panel is warranted to lose no more than 1% in its first year and 0.4% a year after that, keeping 87.4% at year 30 (Jinko datasheet).

Electricity usually gets dearer, which works the other way. US residential prices averaged 12.55¢ in 2016 and 17.23¢ in 2025 (EIA), about 3.6% a year. Here is the New York example with both effects:

Year	Panel output vs new	Price per kWh	Savings that year	Running total (after cost)
Year 1	99.0%	18.2¢	$1,518	−$13,422
Year 2	98.6%	18.8¢	$1,567	−$11,855
Year 5	97.4%	21.0¢	$1,721	−$6,850
Year 8	96.2%	23.3¢	$1,890	−$1,353
Year 10	95.4%	25.0¢	$2,012	$2,609
Year 15	93.4%	29.8¢	$2,350	$13,662
Year 20	91.4%	35.6¢	$2,745	$26,573
Year 25	89.4%	42.5¢	$3,204	$41,647

Output follows the Jinko warranty curve; price rises 3.6% a year, the 2016–2025 US average. Neither is a forecast.

With those two effects the payback comes to about 8.7 years instead of 9.7, and the system is about $41,647 ahead after 25 years. If prices stayed flat, panel ageing alone would stretch it to about 10.0 years.

Step 4: discounted payback, for the cautious

Money saved in year 15 is worth less than money in your pocket today. Discounted payback counts the time for the discounted savings to repay the cost (ACCA). Discounting the New York savings at 5% a year, a rate we chose to represent what the money could earn elsewhere, the payback stretches to about 11.3 years. If your alternative is a savings account paying less, use a lower rate.

Costs people forget

Inverters usually don't last as long as panels. SolarEdge's Home Wave inverter carries a 12-year standard warranty, extendable to 20 or 25 (SolarEdge listing); Enphase gives its IQ8 microinverters 25 years in Australia (Enphase). If yours has a 10–12 year warranty, set money aside for a replacement in the second decade. Batteries add cost but can raise self-use; size one with the battery calculator and add its price to the net cost. Cleaning, monitoring and occasional repairs are small but real.

Common mistakes in payback sums

The most common one is valuing every solar unit at the import price when your scheme pays less for exports. Close behind are counting the fixed part of your bill, such as standing or meter charges, as if solar could remove it, and using output figures for a perfect roof when yours faces east or west or sits in partial shade. PVGIS figures like ours assume panels at the best tilt for the location, so adjust down for a poorer roof. Finally, a quote that shows payback only on the most optimistic price rise is a sales document, not a plan; run it flat as well.

How to shorten your payback

Size the system to what you use while the sun shines rather than to your whole bill, especially where exports pay little. Move flexible loads into the middle of the day. Avoid oversized inverters you don't need, and get three quotes. Our calculator's Bill & Payback tab does the whole sum with your own tariff and shows how your savings build up over time.

Common questions

What is the energy payback time of solar panels?

It's a different measure: how long a system takes to generate the energy used to make it, not the money it cost. Fraunhofer ISE puts it at about 1 to 1.3 years for rooftop systems in Europe and as little as 0.44 years in India, a tiny share of the panels' life.

What is a good solar payback period?

It depends on prices where you live. Our simple examples range from about 3–4 years in Lahore to 10 years in London. The shorter the payback relative to the 25-plus years panels last, the better the investment.

Does the solar payback period include battery cost?

It should if you buy one. Add the battery to the net cost, and count the extra units it lets you use at home instead of exporting. Where export pays far less than import, that extra self-use can justify part of the battery's cost.

How does net billing change payback?

It lengthens payback for systems that export a lot, because exported units earn less. In our Lahore example, raising self-use from 40% to 70% shortens the simple payback from 4.1 to 3.1 years with the same panels.

Is there still a federal solar tax credit in the US in 2026?

Not for homeowners. The IRS says the residential clean energy credit is not allowed for expenditures made after 31 December 2025, and a system counts as paid for when installation is complete.

Does adding more panels shorten the payback?

Only while the extra units replace electricity you would have bought. Once most of the extra output is exported at a low rate, more panels can lengthen the payback. Size to your daytime use first.

Where do I find how much my panels will make?

The European Commission's free PVGIS tool estimates output for any location. Our calculator uses PVGIS data for 14 cities and lets you set your own sun hours, so you can run the payback sum with your own numbers.

Work out your own payback

Enter your bill and tariff in the Bill & Payback tab and the calculator sizes the system and shows your payback year by year.

Open the full calculator →

Sources

Every figure on this page comes from these sources, checked on 30 October 2026.