Should I get solar panels?

Why a single payback figure is close to meaningless

Payback is the number of years it takes for the savings to add up to what you paid. Calculating it needs four numbers: the installation cost, the electricity the panels will actually generate at your address, the proportion of that you use yourself rather than export, and the price of the electricity you would otherwise have bought.

Only the first is fixed at the point of sale. The other three are estimates, and small changes in them move the payback figure by years.

The third moves it most. Electricity you use yourself saves you the full retail price, while electricity you export earns the export rate, which is generally a good deal less. Two identical systems on two identical roofs can therefore produce very different results, depending on whether anybody is at home during the day.

That matters more for retired households than for anybody else, and it works in their favour. A house occupied through the day, with the kettle, the washing machine and the heating running while the sun is up, uses a far higher share of what it generates than one standing empty from eight until six. If you are at home most days, the arithmetic is better for you than the national averages suggest.

What actually decides it for one particular house

Which way the roof faces. South is best in the UK. East and west facing roofs still work, generating perhaps a fifth less across the year, and they have the incidental advantage of spreading generation across the morning and afternoon rather than concentrating it at midday. North facing roofs are generally not worth covering.

The pitch. Around thirty to forty degrees suits UK latitudes. Very shallow or very steep roofs perform less well, though rarely enough to change the decision on its own.

Shading. Shading is the factor most often glossed over in a quotation. A chimney, a neighbouring roof, a television aerial or a mature tree can cut output substantially, and the shadow moves through the day and through the year. A survey carried out on a clear morning in June tells you very little about three o'clock on an October afternoon. A salesman who has not looked at what shades your roof across a full day has not assessed it.

The state of the roof. Panels last a long time. If the roof covering underneath them has ten years left in it, you will pay to have the panels removed and refitted when it is replaced, and that cost is rarely mentioned at the point of sale. Ask a roofer what the roof has left before you ask an installer what the panels would cost.

How long you plan to stay. If the payback period is longer than the time you expect to be in the house, the question becomes what the panels add to the sale price rather than what they save you on bills. Those are different questions with different answers, and the second one is much less certain.

Your actual consumption pattern. Not the annual total, but when in the day you use electricity, which is a different thing altogether and which decides how much of the generation you keep.

What it costs, and what the government currently does

Installation prices vary widely and we will not quote a figure we cannot stand behind for your particular roof. What we can set out is the framework of costs and support, which is public information and changes more often than most people realise.

VAT is currently zero. The zero rate on installing energy saving materials, including solar panels, in residential property runs until 31 March 2027. From 1 April 2027 it is due to return to 5 per cent. On a typical domestic installation that difference is worth a few hundred pounds. It is not a reason to rush, but it is a real date in the calendar.

The Smart Export Guarantee is how you get paid for what you export.It has run since January 2020 and is overseen by Ofgem. Licensed electricity suppliers above a certain size are required to offer a tariff, they set their own rates, and the rate must be above zero. That last point is worth reading twice. There is no minimum beyond above zero, rates differ substantially between suppliers, and you need not take your export tariff from the company that supplies your electricity. Shopping around here is worth real money, and hardly anybody does it.

Grant support is means tested and has changed recently. The Great British Insulation Scheme closed on 31 March 2026. ECO4 was extended to the end of December 2026, but only to allow existing non compliant installations to be put right, and the obligations on suppliers have been discontinued. What exists now sits under the Warm Homes Plan. The Warm Homes Local Grant supports low income owner occupiers and private renters in homes rated D to G on their Energy Performance Certificate, and it can fund solar as well as insulation, batteries and heat pumps. There is also a Warm Homes Fund offering consumer loans rather than grants. The Boiler Upgrade Scheme, which pays £7,500 towards a heat pump, is separate and is not means tested.

Because these schemes change, check the current position on GOV.UK or with your local authority rather than relying on any commercial website, including the date on this page.

Can I get solar panels for free?

It is one of the most searched questions on the subject, and the honest answer is that "free" almost always means one of two quite different things.

The first is a means tested grant, most likely the Warm Homes Local Grant described above. If you qualify, it is genuinely a grant. There is no catch beyond the eligibility rules, and it is worth checking properly rather than assuming you will not qualify.

The second is a lease, sometimes called rent a roof. A company installs panels at no cost to you and keeps the income they generate, either from export payments or from selling you the electricity. You get some reduction in your bills, they get an asset on your roof, and there is usually a contract of twenty or twenty five years attached to the property.

Leases are legal and some people are content with them, but they carry consequences that are not always made clear at the point of signing, and those consequences bite when you come to sell or when the property passes to your estate. A lease attached to the roof has to be disclosed to a buyer. Some mortgage lenders are cautious about them, which can narrow the pool of buyers. Removing panels early, or varying the agreement, may involve a fee.

If anybody offers you free solar panels, the questions to ask are simple. Who owns the panels, who owns the electricity, and what is registered against my property. Get the answers in writing and take the contract to your solicitor before you sign rather than after. That is a modest cost set against a twenty five year agreement on your home.

We would say the same about any doorstep or telephone approach on this subject. A legitimate installer will not mind you taking a fortnight to think about it.

Should I get solar panels or a heat pump first?

They do different jobs, so it is not really a competition, but if you can only do one the order depends on how you heat the house now.

Solar panels generate electricity. A heat pump uses electricity to heat the house, and a great deal more of it than lighting and appliances do. The two therefore work well together, and a heat pump substantially increases the share of your own generation that you use rather than export.

If you are on mains gas and your boiler is working, the case for a heat pump is mostly environmental rather than financial, and the £7,500 Boiler Upgrade Scheme grant is what makes the sums work at all. If you are on oil, or on electric heating, the case is stronger.

Most independent sources say the same thing: reduce the heat the house loses before installing anything that generates or supplies heat. Insulation is unglamorous, nobody knocks on the door to sell it, and it usually costs less than either.

Do solar panels make a house harder to sell?

Owned panels, properly installed and certified, are generally either neutral or mildly positive. Buyers increasingly expect them, and the paperwork is straightforward if you have kept it.

Leased panels cause the difficulty, for the reasons above, as do panels installed without the right certification or without building control sign off where it was needed. Those surface in conveyancing and hold up a sale at exactly the point when delay is expensive.

Keep the installation certificate, the electrical certificate, the manufacturer warranties and the export tariff paperwork together in one place. If you have owned the panels for fifteen years and cannot find any of it, that is worth sorting out before you market the house rather than during.

What we will not do is tell you what panels add to your property's value. Nobody can put a reliable figure on that for an individual house, and anybody who offers one is guessing.

What is the 20 per cent rule for solar?

There is no such rule in the United Kingdom. It turns up in searches often enough to be worth saying plainly.

The phrase seems to travel over from American guidance, where it is variously used to describe a tax credit, a rule of thumb about how much of a roof to cover, or a target for how much of your bill to offset. None of those maps onto anything official here. If somebody quotes you a 20 per cent rule as though it were a British standard, ask them what they are referring to.

The same goes for several other rules of thumb in circulation. With solar the general figure is nearly always less useful than the specific one, which is precisely why so much of the available advice is unsatisfying.

Why people search for what Martin Lewis thinks

Because they want an opinion from somebody with no stake in the answer. The instinct is exactly right, and it deserves applying more widely than to one man.

When you read anything about solar, including this page, ask what the writer gets if you say yes. A company that fits panels, a company that generates leads for companies that fit panels, and a company that sells you a comparison service all have an interest in the same answer. That does not make what they say false. It does mean their estimates tend to sit at the optimistic end, and that the four numbers behind any payback calculation are worth asking about one by one.

What we cannot answer from here

Whether it is worth it for you. That needs the numbers for your roof, your consumption and your circumstances, and two of the three are yours rather than ours.

What is knowable in advance is the part about the building and the site. Orientation, pitch, the shading that falls across the roof through the day and the seasons, and what the sun actually does at that address across a year. Those are matters of public record and physical fact, and they are the half of the question that gets least attention because nobody makes money by answering it honestly.

Our Heat & energy module covers orientation, solar exposure, overheating risk and local climate records for a specific address in England or Wales. We do not sell, fit or recommend solar panels, we take no commission from any installer or supplier, and we have no view on whether you should proceed. It is not a survey, and we do not visit the property.

Contains public sector information licensed under the Open Government Licence v3.0.