Guide: solar

Are solar panels worth it?

For some UK households solar is one of the better things you can do with several thousand pounds. For others it is a long, dull wait for a modest return. The difference is not luck, and it is not the brand of panel. It comes down to four things you can check before you speak to anyone.

Last reviewed: September 2026

The four variables that decide it

01How much electricity you use, and when. Solar rewards daytime consumption. A household that is out from eight until six with no timers or storage exports most of what it makes.
02What you pay to import. The value of every self-consumed unit is the import price you avoid. A high import price makes solar look considerably better than a low one.
03What your roof can actually generate. Orientation, pitch, usable area and shading decide annual output. South is best, east and west are workable, north is not.
04What you pay for the installation. A good price on a suitable roof beats a premium price on a better one.

Who tends to do well

Households with someone home during the day, or with loads that can be shifted into daylight hours.
Homes with an unshaded roof facing somewhere between south east and south west, with room for a sensibly sized array.
Households with high electricity consumption, particularly those running a heat pump or charging an electric car at home.
People staying in the property long enough for a payback period measured in years to be meaningful.
Households willing to change behaviour slightly, running the dishwasher, washing machine and hot water in the middle of the day.

Who tends to do less well

Low-consumption households, where there is simply not much import cost to avoid.
Homes that are empty all day with no storage, no timers and no flexible loads.
Heavily shaded roofs, where chimneys, trees or a neighbouring building cut output for a large part of the day.
Small or awkward roofs where fixed costs such as scaffolding and electrical work are spread across very few panels.
Households planning to move within a couple of years, who will not see the benefit accumulate.

Self-consumption is the number that matters

Every unit you generate and use at home saves you the import price. Every unit you export earns the export rate instead, which under the Smart Export Guarantee is set by suppliers and is generally well below what you pay to import. We do not publish specific rates here because they vary by supplier and change, but the structural point holds: self-consumed electricity is worth several times more than exported electricity.

This is why a bigger system is not automatically a better system if most of the extra electricity leaves your roof for pennies. It is also why the self-consumption percentage in a sales spreadsheet deserves more scrutiny than any other figure in it.

You can raise self-consumption without spending more on panels: run heavy appliances in daylight, heat water with a diverter, and charge a car during the day when you can. A battery raises it further, but that is a separate purchase with its own arithmetic.

What payback does and does not tell you

Simple payback is the installed cost divided by the annual benefit. It is a useful first filter and a poor final answer. It ignores the time value of money, finance costs, panel degradation, inverter replacement, maintenance and any future change in energy prices or export terms.

Use it to sort the obviously good from the obviously marginal, then stress test it. Reduce the generation estimate, reduce the self-consumption share, and see whether the decision survives. If it only works at the optimistic end of every assumption, it is tighter than it looks.

Common mistakes

Judging solar on the headline generation figure rather than on avoided import cost.
Assuming a high self-consumption share for a household that is out all day.
Oversizing the array because the price per kWp falls, without checking where the extra output goes.
Ignoring the export side and never signing up to a Smart Export Guarantee tariff.
Bundling a battery into the decision so the panel economics can never be seen on their own.
Treating a quoted payback as a forecast rather than as an arithmetic result from someone else's assumptions.

Questions to ask an installer

What annual generation do you predict, and how did you model shading?
What self-consumption share is your savings figure based on, and why that figure?
What does the benefit look like if self-consumption is ten points lower?
What would you size this array at if you were paying for it yourself?
Which supplier export tariffs are you assuming, and am I free to switch?

Test it with your own numbers

Enter your consumption, your import price, your quoted cost and a realistic self-consumption share. Then lower the optimistic assumptions and look again.

Open the solar calculator What solar actually costs

Keep reading

Solar panels

The full decision page, including quote checks.

Is a home battery worth it?

The storage decision, priced separately.

Methodology

What our estimates include and exclude.

Support schemes can change the arithmetic for some households. See the grants page for current UK schemes and official sources.