For many UK homes, solar panels are worth it if you stay put for more than ten years and use a good share of the power yourself. On our illustrative figures below, a typical 4kW system pays back in about 10 to 11 years. Your own number could be shorter or longer.

The honest answer is “it depends”, because the cost, your daily routine and your tariff all matter. This guide shows the sums so you can test them with your own quote and your own bills.

What a typical system makes

A 4kWp system can generate around 3,400kWh a year, according to the Energy Saving Trust solar calculator. Your figure depends on where you live, which way the roof faces and how much shade it gets. For example, a roof facing south with no trees nearby does best. Our guide to how many panels you need explains how size and output link up.

Output also changes through the year. Summer gives most of it, while winter gives far less. That is normal, since days are shorter. Our post on solar panels in winter shows what to expect on short, dull days.

What it costs

Government data for 2025/26 puts the median price at about £1,595 per kW for systems up to 4 kW. That is roughly £6,400 for a 4 kW system (DESNZ, published May 2026). Your quote may differ. Read more in our guide to how much solar panels cost.

Installing solar currently carries 0% VAT. However, that relief ends on 31 March 2027, when the rate is due to rise to 5%, according to HMRC’s VAT Notice 708/6.

How the savings work

Solar saves you money in two ways. First, every unit you use from your own roof is a unit you do not buy. Second, you can sell spare power back to a supplier. Ofgem explains that the Smart Export Guarantee (SEG) requires licensed suppliers to offer export tariffs to small solar generators, as set out in Ofgem’s SEG guidance.

The two are not equal. Because power you use yourself saves you the full price you would pay. Power you export earns you a lower rate. So the more you use at home, the better your return.

An illustrative example

These numbers are an example, not a promise. Assume a 4kWp system that makes 3,400kWh a year. Assume you use 40% yourself and export the rest. Assume you pay 26.32p per kWh for imported power (the Ofgem cap for October to December 2026). Assume you earn 12p per kWh on exports.

  • Power used at home: 1,360kWh, saving about £358.
  • Power exported: 2,040kWh, earning about £245.
  • Total: about £603 a year.

At £6,400, that is a payback of about 10.6 years. The 12p export rate matches Outgoing Octopus, a variable tariff that Octopus Energy listed at 12p per kWh on 10 October 2026, but you must be an Octopus import customer to get it. Rates also change, so read our Smart Export Guarantee explainer and check the supplier page before you sign up.

The unit price matters too. Ofgem’s price cap for October to December 2026 puts a typical dual-fuel bill at £1,723 a year, up from £1,663, as the Ofgem summary of changes shows. Higher bills mean each unit you generate saves more, since you avoid buying it. Use the rate on your own bill for your sums.

What makes the return better

You can often improve the payback without buying more panels, because behaviour matters. The main lever is to use more of your own power.

  • Run the washing machine and dishwasher in the day.
  • Heat hot water with spare solar power.
  • Charge an electric car when the sun is out.
  • Shift use away from the evening peak.

Our guide to using more of your own solar power goes through the options in detail. Charging a car is a big one, and the post on charging an electric car from solar covers it.

A smart tariff can also help. Some tariffs charge less at set times, so they suit a home with a battery. Read about time-of-use tariffs with solar and a battery before you pick one.

Is a battery worth it?

A battery stores spare power for the evening. That lifts your self-use, so each unit saves you more. However, a battery adds a lot to the upfront price. It also has its own lifespan and warranty.

The simple test is to compare the extra yearly saving with the extra cost. In many homes the battery pays back more slowly than the panels. Our guide to solar battery cost and sizing shows how to run that check. Our batteries and export guide covers the wider picture.

A quick way to test your own numbers

You do not need a spreadsheet. Take three figures from your quote and your bill. These are the yearly output, the price per unit you pay, and the export rate on offer. Then split the output into the share you use and the share you export.

Multiply each share by its rate and add them up. Divide the system price by that total. The result is your payback in years, although it is only an estimate. For example, if you use more power than the 40% we assumed, the payback gets shorter.

Next, ask the installer to show their own estimate and the assumptions behind it. A good installer will give you the yearly output, the self-use share and the rates used. If a quote hides these, ask why. Our guide to choosing an installer has more on spotting vague claims.

Prices can change

Electricity prices move, and export rates move as well. The government has cut VAT on electricity bills from 5% to zero from 1 October 2026 to 31 March 2027, according to Ofgem. That lowers your bill for now, so it trims the saving from each unit by a small amount. Even so, one winter does not decide a long-term choice.

Running costs and lifespan

Panels have no moving parts, so they need little care. The inverter, which changes direct current to the mains type, is often the first part to wear out. Our post on solar inverters explained covers what that means for your costs.

Panels also lose a little output each year, however slowly. Our guide to how long solar panels last explains how fast, and our maintenance and lifespan hub lists the checks that keep a system healthy.

When solar is a poor bet

Solar is a weaker choice in a few cases.

  • Your roof is heavily shaded all day.
  • You plan to move within a few years.
  • You are on a very low electricity use and rarely at home.
  • The roof needs major repair soon.

If any of these apply, get advice before you spend, because the sums may not work. Our costs and savings guide lists the figures to check. Our explainer on how domestic solar panels work is a good starting point if you want the basics first.

Sources

Common questions

How long do solar panels take to pay for themselves?

It depends on your system price, how much power you use at home and your export rate. On the illustrative figures in this guide, a 4kW system pays back in roughly 10 to 11 years. Homes that use more of their own power can do better.

Do solar panels still work on cloudy days?

Yes, but they make less power. Output falls in winter and on dull days. Annual figures already allow for this.

Is a battery worth adding?

A battery lets you store spare power for the evening. It also adds several thousand pounds to the price, so it needs its own payback check. Compare the extra saving with the extra cost before you buy.

Do solar panels add value to a home?

We have not found a reliable official figure, so treat any claim with care. Buyers may like lower bills, but a firm number varies by area and property.

What if I plan to move soon?

Then payback matters more. If you move in a few years you may not earn back the cost. Keep your MCS certificate and warranties so a buyer can see what they get.