Solar Panels FAQ: UK Homeowners' Guide

A typical home system is 4 kWp, which is 9–10 panels of 430–450 W and about 18–20 m² of roof. The exact number depends on panel size, because bigger panels need fewer. A 3 kWp system needs about 7 panels. Use the solar panel calculator to estimate your own size.

In England, since 27 August 2026, rooftop solar on a house is usually permitted development: no more than 200 mm proud of a pitched roof and no higher than the ridge, or up to 600 mm above a flat roof. Scotland, Wales and Northern Ireland have their own rules. Check with your council if your home is listed, in a conservation area, or covered by an Article 4 direction.

The best angle is about 35–40°, facing due south. Anything from 20° to 45° costs you no more than about 4%. South-east roofs give about 95% of that and south-west about 93%, while east or west roofs give about 80%.

Yes. Flat roofs normally use tilted frames, which help because panels laid flat make only about 83% of the best output. In England a flat-roof array can stand up to 600 mm above the roof under permitted development.

Fitting a full roof system yourself is risky, because without an MCS certificate you can't get paid under the Smart Export Guarantee. Use an MCS-certified installer. Small plug-in kits are the exception, as the next answer explains.

Since 27 August 2026, plug-in solar kits of up to 800 W output that meet the government's product specification can legally be plugged into a normal socket in Great Britain. You must tell your network operator, use only one kit per home, and never use an extension lead. Read more about plug-in solar panels.

Panels typically last 25–30 years or more. Good modern panels lose roughly half a percent of output a year, so after 25 years they still make around 85–90% of their original output. You may need to replace the inverter once during that time.

On our 900 kWh per kWp assumption, a 440 W panel makes about 400 kWh a year, and a 4 kWp system averages about 10 kWh a day. However, December output is roughly a quarter to a third of June's. See how panels perform in winter and cloud.

Yes, although they make less. Using the EU's PVGIS model, south-facing panels at 35° make about 945 kWh per kWp in Leeds and about 850 in Glasgow, against about 1,025 in London. Read what solar generates in Leeds for local detail.

Panels need little upkeep, and rain clears most dirt. However, birds can nest under them, so see keeping pigeons out from under panels. For routine care, read about looking after your panels.

The panels stay with the house, because they are fixed to the roof. Buyers usually value the lower running costs. Ask the seller for the MCS certificate, the warranties and the export tariff details. See buying a house that already has solar panels.

Some do, but specifications differ. Ask the developer exactly what is included and who owns the system, since that affects your export payments. Check the warranty and the MCS certificate before you complete. Our guide covers new-build solar rules.

The Smart Export Guarantee (SEG) replaced the Feed-in Tariff on 1 January 2020. Suppliers in Great Britain must pay you for electricity you export. It does not cover Northern Ireland, because Ofgem does not regulate it there.

There is no fixed SEG rate. Each supplier sets its own, so it pays to compare, and open-market rates are about 3–6p per kWh. Outgoing Octopus pays 12p (October 2026), but only if you also buy your electricity from Octopus. See the best Smart Export Guarantee rates.

Contact a supplier after your panels are installed by an MCS-certified installer. You need the MCS certificate and a meter that measures your export, normally a smart meter. The best rates usually need you to buy your electricity from the same supplier, although open-market tariffs exist.

On our model a 4 kWp system exports about 2,520 kWh a year. At 12p per kWh that earns about £302, while at an open-market 4.1p it earns about £103. Your own figure depends on how much you use at home.