Solar Panels vs Photovoltaic Systems: What UK Homeowners Need to Know

Both systems harvest sunlight, but they do different jobs. This guide covers the key differences between photovoltaic vs solar panels, so you can choose the right fit for your home.

Solar PV and solar panels are not the same as solar thermal

The confusion is understandable. Both sit on a roof and both use the sun. But the photovoltaic vs solar panels debate often overlooks a third term entirely: solar thermal. Photovoltaic (PV) panels convert sunlight into electricity, while solar thermal collectors convert sunlight into heat, usually to warm your hot water cylinder.

When most people say 'solar panels', they mean PV. The two terms describe the same product: panels made of silicon cells that generate a direct electrical current when light hits them. Solar thermal is a separate technology, with different components, a different purpose and a different cost structure.

Knowing which problem you are trying to solve, reducing your electricity bill or cutting your hot water costs, is the single most useful question to answer before you go any further.

What each system actually does in your home

A PV system feeds electricity into your home's circuit. Power you generate but don't use immediately can be exported to the grid under the Smart Export Guarantee (SEG); for full detail on how that export payment works and what it requires, see our guide on photovoltaic panels.

A solar thermal system uses a roof-mounted collector to heat a fluid, which transfers its heat to a dedicated hot water cylinder. It does not generate electricity at all. On a well-sized system it can cover a significant share of your annual hot water demand, but it contributes nothing to lighting, appliances or EV charging.

The practical result: if your priority is cutting electricity costs or earning export payments, PV is the relevant technology. If your hot water bill is the target and you already have a suitable cylinder, solar thermal deserves a close look.

Cost, payback and what drives the numbers

Solar thermal installation typically costs between £3,000 and £6,000 according to Renewable Energy Hub (2026), while a domestic PV system generally runs higher. The Energy Saving Trust (Jul 2026) puts a typical installed PV system at £5,000 to £10,000. Both figures depend on system size, roof type, scaffolding needs and the installer's labour rate in your area.

Payback for PV depends on how much of the electricity you use directly rather than export, your current tariff, roof angle and shading. The Energy Saving Trust puts the typical payback at 9 to 12 years on an ideal roof, with longer periods for east-facing or shaded setups. Solar thermal payback is driven by how much hot water your household uses and whether it displaces gas, oil or electric heating.

Neither system's payback can be stated as a single number without knowing your home. What you can do is ask installers to show their working, including consumption assumptions, roof angle and shading, so you can compare proposals on the same basis.

Roof suitability: what the two systems need

Both technologies favour a south-facing roof pitched between 30 and 50 degrees, with minimal shading between 9am and 3pm. Beyond that, their needs diverge. For a fuller roof suitability checklist, see the dedicated section on this page.

PV panels are relatively flexible: modern panels perform well on south-east and south-west aspects, and multiple strings can face different directions. East-facing arrays still produce useful output, though annual yield drops compared to a south-facing roof. If your roof is old or in poor condition, have it assessed before installation; replacing tiles under a fitted array costs more than doing the work first.

Solar thermal collectors are more sensitive to pitch and aspect because they rely on consistent heat transfer. They also require space for a larger hot water cylinder, typically an unvented unit with a twin coil. Flat-panel collectors and evacuated tube designs cope differently with UK winter light, so the choice of collector type matters in less sunny regions.

Battery storage: useful with PV, not relevant to thermal

A home battery stores surplus electricity from your PV array and releases it when the panels are not generating, in the evening and overnight, for instance. This raises the share of your own generation that you actually consume, which is where the financial gain is strongest. Whether the cost of adding storage is justified depends on your daily usage pattern, overnight draw and the gap between your import and export tariffs.

Solar thermal has no meaningful link to battery storage. It produces heat, not electricity, so a battery adds nothing to a standalone thermal system. If you are weighing up whether battery storage changes the numbers on a photovoltaic vs solar panels decision, our guide on whether a battery is worth adding covers the key scenarios in detail.

For a household with high daytime electricity use and low overnight consumption, a battery may add relatively little. For a household that is out all day, it can shift the self-consumption ratio and improve the overall return.

Permitted development, planning and building rules

Most domestic rooftop PV setups fall under permitted development rights in England, meaning no planning application is needed. The rules were updated under the GPDO changes for 2026. Exceptions apply to listed buildings, conservation areas, and any array that would protrude more than 200mm from the roof plane or sit on a wall facing a highway.

Solar thermal collectors follow broadly the same permitted development framework, with the same exceptions: listed buildings and conservation areas will usually require a formal planning application, and local aesthetic rules can restrict panel colour or collector type. Always confirm with your local planning authority if your property carries any designation.

Flat-roof and ground-mount systems, whether PV or thermal, are more likely to need permission, as are commercial setups. If you are unsure about your property's status, your installer should be able to advise, but the final decision rests with the local planning authority.

Warranties, maintenance and the long view

Panel warranties give a reasonable picture of long-term performance. PV panels typically carry product warranties of 20 to 25 years, while inverters tend to have shorter lives of around 5 to 15 years, according to the Energy Saving Trust and Which?. Budget for inverter replacement at some point and factor that cost into your payback calculation.

PV systems have no moving parts in the panels themselves and need minimal upkeep: a periodic clean and an annual check of the inverter and connections is typical. Solar thermal systems are more complex mechanically. The heat-transfer fluid needs topping up or replacing every few years, the pump and expansion vessel need periodic servicing, and frost protection should be checked before winter.

Both systems benefit from being fitted by an MCS-certified installer. MCS (Microgeneration Certification Scheme) certification is required to access the Smart Export Guarantee for PV, and it is a useful quality marker for thermal work too. Check that your installer holds the relevant MCS certificate for the technology they are fitting.

Sources

• Renewable Energy Hub - Solar Photovoltaic (PV) vs Solar Thermal (2026) (2026)

• Energy Saving Trust (Jul 2026) (2026)

• HMRC / VAT Notice 708/6 (2026)

• MCS (2026)

• eia.gov - Photovoltaics and electricity