Types of Solar Panel Sold in the UK

Solar photovoltaic (PV) panels capture energy from the sun and turn it into electricity for your home to use¹. The cells inside them convert light into a direct electrical current, and an inverter changes that into the alternating current your appliances run on². Nearly 1.7 million installations now sit on homes across the UK³, and the technology comes in a small number of families: crystalline cells, thin-film and hybrid designs². Solar thermal panels, which heat water rather than generate electricity, are a separate product and the most popular form of solar energy used in the UK⁴.

For a householder choosing panels, the practical differences between these families come down to three things: how much electricity a given roof area will produce, how the panels look, and what they cost. A typical installation of around 3.5 kilowatt peak (kWp) uses between six and 12 panels, costs around £6,100, and saves between £530 and £650 a year on electricity bills¹. This page explains the panel types sold in the UK, what separates them, and what each choice means for a home that wants to generate more of its own power.

What a solar panel does, and the panel families sold here

A solar panel's job is simple: it converts sunlight directly into electricity, which can then be used in the building⁶. The photovoltaic cells produce a direct current, which needs to pass through a solar inverter to become alternating current, the kind of electricity a home actually uses¹. Everything else about a panel, its cell type, its frame, its colour, is a variation on that single function.

The panels sold for UK roofs fall into a few families. The dominant technology is crystalline silicon, in two forms: monocrystalline and polycrystalline. Thin-film panels, built from materials such as amorphous silicon, cadmium telluride and copper indium gallium selenide, are a third family, and hybrid designs combine approaches². Alongside these sit the physical formats: standard framed panels mounted on top of the roof, roof-integrated panels, and PV tiles and slates that resemble traditional roof coverings⁷. Solar thermal is a different product altogether, heating water rather than making electricity, and comes as flat plate or evacuated tube collectors⁴.

Roof mounting is by far the most common option for domestic installations, with ground mounting the main alternative⁵. Panels can be fitted to both pitched and flat roofs, though a flat roof needs tilted, spaced mounting to avoid one row shading the next¹. The UK market is also set to grow: the UK Government is expected to include requirements in its Future Homes Standard for most new builds in England to have solar panels⁸.

Types of solar panel explained

Monocrystalline solar panels are the most efficient panels currently available for domestic properties⁵. Their increased efficiency comes from the single-crystal silicon that makes up the photovoltaic cells: because the silicon is one continuous crystal, electrons flow through it with less resistance and more of the incoming light becomes usable electricity.

Polycrystalline panels are made by melting small silicon crystals together rather than using a single, larger fragment of silicon⁵. The process is simpler and the crystal boundaries interrupt the flow of electrons, so a polycrystalline panel of the same size produces less electricity than a monocrystalline one. Scheme documentation from a Welsh solar installation programme puts polycrystalline modules at averaging around 14 to 15% efficiency⁹.

The gap in output shows up in real purchasing decisions. That same Welsh scheme specifies monocrystalline panels for all installations and states that polycrystalline panels must not be installed in its properties unless otherwise approved⁹. A householder buying panels today will mostly be offered monocrystalline modules as standard.

Thin-film panels are less efficient than either crystalline type⁵. They are made by depositing a photovoltaic material as a thin layer, using substances such as amorphous silicon, cadmium telluride and copper indium gallium selenide⁵. Their lower efficiency means more area is needed for the same output, which matters on a small domestic roof, and they are uncommon in UK residential installations as a result.

For a deeper look at the cell technologies inside current panels, see solar cell technology, and for the glass-glass and bifacial designs now sold alongside standard modules, see bifacial and glass-glass solar panels.

All-black panels and roof-integrated PV: how the choices look

Appearance is a genuine deciding factor for many households, and the market has responded with two main options. All-black, or full black, modules use black cells, a black backsheet and a black frame so the panel reads as a uniform dark surface rather than a grid of blue-grey squares with a silver edge. The monocrystalline cells that make this possible are the same cells that give the highest efficiency, so a household choosing all-black panels is not trading away output for looks.

The second option changes where the panel sits. Solar PV can be installed in the form of PV tiles and slates, which work in the same way as traditional solar PV panels but resemble traditional tiles or slates⁷. These suit roofs where a flush, conventional appearance matters most, and they overlap with roof-integrated systems, where standard panels sit within the roof plane rather than on top of it. The trade-off is cost and complexity: integrated products replace part of the roof covering, so fitting them is a bigger job than bolting framed panels above the tiles. The comparison between the two approaches is covered in roof-integrated solar and solar panels vs solar roof tiles.

Understanding panel efficiency ratings

A panel's efficiency rating states what proportion of the light landing on it is converted into electricity. Monocrystalline panels lead the field for domestic properties⁵, polycrystalline modules average around 14 to 15%⁹, and thin-film panels sit below both⁵. In practice, efficiency is mainly a space question: a more efficient panel makes more electricity from the same area, so a small roof benefits from it most, while a large roof can reach the same total output with more, cheaper panels.

Two things change the rating over time. The first is degradation, the slow loss of output as panels age, which is covered below. The second is the conditions on the day: panels need only daylight, not direct sunlight, so they generate under cloud, though less than under clear sky¹⁰. Even on a cloudy day, good generation can be achieved¹². A system facing east or west tends to get around 15 to 20% less energy than one facing directly south¹, so orientation moves real output more than the choice between two similar panel models does.

For what the numbers on a datasheet actually mean, see reading a solar panel datasheet.

How many panels your roof can hold

The starting point is the roof itself. It must be in good condition, because panels will sit on it for decades, and if it is heavily shaded, solar panels may not be the most suitable option¹³. Beyond that, three numbers drive what fits.

A 3.5 kWp system typically covers between 10 and 20 square metres of roof surface¹. A larger 4.5 kWp system typically covers between 20 and 30 square metres, using around 12 panels¹⁴. For comparison, a solar thermal water heating system needs 3 to 4 square metres of southeast to southwest facing roof receiving direct sunlight for the main part of the day¹⁵, so the two solar technologies make very different demands on a roof.

Panel counts from uSwitch and Energy Saving Trust¹¹.

A typical professionally installed rooftop system is around 4.6 kW¹⁶, which sits above the 3.5 kWp average, so many households are now fitting more panels than the minimum. Orientation matters too: east or west facing systems lose around 15 to 20% of output against a south-facing one¹, a loss many roofs have to accept. The full picture is in roof orientation, pitch and shading and what size solar system a home needs.

Price, savings and when they pay back

A typical solar panel installation costs around £6,100 for a roughly 3.5 kWp system¹. Against that, a typical home without electrical heating or an electric vehicle saves between £530 and £650 a year on electricity bills¹. How much a household actually saves depends on when it uses electricity: if someone is home all day, the saving is around £650 a year, and if everyone is out until 6pm, around £530 a year¹.

That pattern exists because rates for selling electricity to the grid are much lower than tariffs for using electricity from the grid, so using solar electricity yourself is much more cost-effective¹. A household that shifts its washing, cooking and charging into daylight hours gets more from the same panels.

Payback estimates vary with the assumptions behind them:

• Energy Saving Trust puts the payback period at about 10 to 12 years, and as little as nine years in the best cases³.
• Hammersmith and Fulham Council states panels usually pay for themselves in 10 to 12 years¹.
• uSwitch gives a shorter typical payback of 7 to 10 years¹².
• Which? calculated a break-even of 10.9 to 12.2 years for rooftop systems¹⁶.

The figures differ because they assume different system prices, electricity tariffs and usage patterns, but they cluster around a decade. The detail behind these numbers is in solar panel costs and savings and payback.

Approvals and rules for installing panels

Solar panels often do not need planning permission because they are considered permitted development, with exceptions for listed buildings and homes in conservation areas¹. In conservation areas and on listed buildings, planning permission may be required¹⁷. If the property is listed, planning permission and listed building consent are always needed¹⁸, and consent extends to buildings within the curtilage of a listed building that pre-date July 1948²⁰. Planning permission is also required for panels on flat roofs in conservation areas¹⁹.

Building regulations are a separate matter. Installing a solar panel on a roof requires a building regulations application, because the roof's strength must be assessed and may need strengthening, and the associated electrical works are also covered¹⁸. The simplest route through this is certification: the best way to avoid problems with building regulations is to use an MCS certified installer for the fitting²².

Finally, the system must be registered. In UK Power Networks areas you must register the installation with UKPN, usually done by your installer¹; more generally, every system needs registering with the local Distribution Network Operator³. The connection process is explained in G98 and G99 grid connection, and the permission rules for each nation in planning permission in England, Scotland, Wales and Northern Ireland.

Lifespan, degradation and maintenance over 25 years or more

Panels last a long time. They will last 25 years or more¹, with estimates of 25 to 30 years for new panels, varying with their environment²⁴, and up to 30 years when properly maintained¹². The average lifespan before panels show significant degradation is about 25 years¹¹.

Degradation is the number to watch. After 25 years, many solar panels will have experienced degradation rates of anything between 12.5% and 75%¹¹. That range is wide because it depends on the panel quality, the climate and how well the system has been looked after, but it is a reminder that a 25-year-old system produces less than it did when new.

The inverter is the short-lived component. Inverters usually need replacing after around 12 years¹, and independent guidance gives 10 to 12 years⁵. When budgeting for a system over its full life, a household should expect at least one inverter replacement, and possibly two, before the panels themselves reach end of life. Inverter types and lifespans are covered in solar inverters.

Maintenance is light. Energy Saving Trust recommends cleaning panels every 12 to 18 months, and professional cleaning costs around £4 to £15 per panel¹². A heavily soiled system loses output, but rain handles much of the work on a pitched roof. The full routine is in solar panel maintenance and cleaning.

Panel and installer guarantees compared

Solar panels usually come with a 25-year performance warranty and a five to 10-year product warranty⁸. The distinction matters. The product warranty covers defects in the panel itself, faults in materials or workmanship, and runs out long before the panels do. The performance warranty guarantees that the panels will still produce a stated share of their original output after a set number of years, which is the warranty that speaks to the degradation figures above.

A typical rooftop system carries a 25-year warranty, while plug-in solar panels typically carry 10 years¹⁶. The inverter has its own warranty, usually shorter than the panels', and it is the component most likely to need a claim within the first two decades⁸.

Installer cover is the third layer. An MCS certified installation comes with certification paperwork that matters both for building regulations and for any future claim, and a TrustMark registered installer operates under a government-endorsed quality scheme²⁵. A household buying a system that is expected to run for 25 years or more should keep every certificate. The detail is in solar panel warranties, degradation and lifespan.

VAT on solar panels and batteries

Solar panels qualify for a lower rate of VAT²⁷. The eligible supply covers photovoltaic panels with cabling, control panel and AC/DC inverter²⁸, so the installation is treated as a whole rather than as a pile of parts taxed separately.

Batteries get specific treatment. The combined installation of solar panels and a battery for storage of the power generated from the solar panels is treated as a single supply of the installation of solar panels²⁹. In practice this means a household adding a battery at the same time as the panels is not buying two separately taxed products.

The VAT position is favourable now, but it is set by government and can change. A household comparing quotes should check that each quote states the VAT treatment clearly, so the prices are genuinely comparable. Battery storage options are covered in adding battery storage to a solar system.

MCS and TrustMark accreditation

Two certifications matter when choosing an installer. The first is MCS, the Microgeneration Certification Scheme. Official guidance recommends using an installer certified by MCS¹³, and the best way to avoid problems with building regulations is to use an MCS certified installer for the fitting²². Certification is not a formality for grant-funded work either: for solar panels to be eligible for the WH:SHF scheme, they must be installed using an MCS approved product, by an MCS certified installer, to the relevant MCS installation standard²⁵.

The second is TrustMark. Scheme rules require that the company providing the installation carries a valid TrustMark registration and is MCS certified⁹, and ECO4 guidance requires measures to be installed by or under the responsibility of a TrustMark registered installer, with a relevant certificate of lodgement²⁶. One Welsh scheme goes further still, requiring that solar PV systems are installed and certified by MCS certified contractors working to the latest published MIS3002 standards⁹.

For a householder, the practical check is simple: confirm both certifications before signing, and verify the installer on the MCS website. The scheme is explained in MCS certification for solar PV.

Does your panel choice affect energy independence?

A solar installation is one of the few home improvements that reduces a household's dependence on its electricity supplier in a direct, physical way: the panels make electricity on the roof, and every unit used in the building is a unit not bought from the grid. Because rates for selling electricity to the grid are much lower than tariffs for using it, the independence is worth most to a household that runs its appliances while the sun is up¹.

The choice of panel type shapes how much independence a given roof can deliver. Monocrystalline panels, the most efficient available for domestic properties⁵, extract the most from a small or awkward roof; polycrystalline panels at around 14 to 15% efficiency⁹ need more area for the same output; thin-film panels, less efficient again⁵, are rarely the practical choice for a UK home.

The dependence that remains is just as real. The system still needs the grid as a backstop, and must be registered with the local network operator³. The inverter, which generally needs replacing after around 12 years⁸, is a manufactured component the household cannot service itself. And the panels themselves are imported manufactured goods, warrantied by their maker over decades. Solar panels give a household a large measure of energy self-sufficiency, but not autonomy: the roof generates, the grid balances, and the warranties and certifications above are what make the whole arrangement durable.