How Do Solar Panels Work?

Solar panels convert sunlight into electricity using the photovoltaic effect — a process first discovered in 1839 but only made practical for homes in the last two decades. The technology is now mature, reliable, and the single most cost-effective way for UK homeowners to generate their own clean electricity.

The principle is straightforward. Silicon cells in each panel absorb light energy, which excites electrons and creates an electrical current. This happens whenever there is daylight — not just direct sunshine — which is why solar panels work well in the UK despite our reputation for grey skies. Wiltshire receives approximately 1,620 hours of sunshine annually with solar irradiance of 980 kWh/kWp, making it one of the better-performing regions in the country.

A typical residential system uses between 10 and 16 panels (4-6.5kW), generating enough electricity to cover 60-80% of an average home's annual consumption. With battery storage, that figure rises to 80-90% by capturing daytime surplus for evening use.

Types of Solar Panel

There are three main types of solar panel technology used in UK residential installations:

Monocrystalline panels are the most efficient (20-22% efficiency), made from single-crystal silicon. They perform better in low light and have the longest lifespan. These are what Lumos Energy installs as standard — the higher upfront cost is more than justified by superior long-term performance.

Polycrystalline panels are slightly less efficient (15-18%) and cheaper, made from multiple silicon crystals. They are recognisable by their blue speckled appearance. Once popular, they have been largely superseded by monocrystalline.

Thin-film panels are the least efficient but most flexible, sometimes used on flat roofs or unusual surfaces. They are rarely used in UK residential installations.

Do Solar Panels Work in Winter?

Yes. Solar panels generate electricity in all daylight conditions, though output is lower in winter when days are shorter and the sun is lower in the sky. A typical UK system generates around 60-70% of its annual output between April and September, with the remaining 30-40% coming from October to March.

Cold temperatures actually improve panel efficiency — silicon cells perform better when cool. A bright, cold winter day can produce surprisingly strong output. Snow covering panels will temporarily reduce generation, but UK snowfall is rarely prolonged enough to make a meaningful difference annually.

Making the Most of Your Solar

The key to maximising return on your solar investment is self-consumption — using as much of your generated electricity as possible rather than exporting it. Without a battery, a typical home uses 30-50% of its solar generation. The rest is exported at a fraction of what you would pay to buy it back.

Three strategies to increase self-consumption: run energy-intensive appliances (dishwasher, washing machine, tumble dryer) during the day when your panels are generating; add battery storage to capture surplus for evening use; and install a solar-integrated EV charger to charge your car with free electricity.