How solar panels work
The simple version of what panels do, what affects them and what to ask next.
Solar panels turn daylight into electricity. That sentence is almost always where the useful explanations stop — and the jargon starts. This guide keeps it plain.
What a solar panel actually does
Each panel is made up of cells. When daylight hits a cell, it knocks electrons loose and they flow as a direct current (DC). An inverter in your home converts that into the alternating current (AC) your appliances use. That is essentially the whole story.
What changes how much electricity you get
The most important factors are: how much of your roof faces south (or near-south), whether anything shades the panels during the day, the angle of your roof pitch, and of course how sunny your part of the UK tends to be. South-facing, unshaded roofs at around 35–40° pitch generate the most — but east- or west-facing roofs still generate a useful amount.
What the kWp number means
Panels are rated in kilowatts-peak (kWp). This is the amount of electricity a panel produces under ideal laboratory conditions — full midday summer sun, no shade, perfect temperature. Real-world output is always lower, but the rating is a consistent way to compare panels and size a system. A typical UK home might benefit from a 4–6 kWp system.
What the inverter does
The inverter is the box that converts DC from the panels into usable AC electricity. It also connects your system to the grid and reports on how much you are generating. Inverters come in two main types: string inverters (one unit for the whole array) and microinverters or optimisers (fitted to each panel individually, which helps when shading is a concern).
Do the panels need direct sunshine?
No — they generate electricity from daylight, not heat. A bright overcast day still produces useful electricity, just less than a clear summer day. Temperature actually matters too: panels are slightly more efficient when cool, which is why spring often produces more than a hot August afternoon.
Key takeaways
- Panels convert daylight (not heat) into electricity via an inverter.
- kWp is the peak rating — real output will always be lower.
- South-facing, unshaded roofs generate most, but other orientations still work.
- Shade on even one panel can reduce output from the whole array unless optimisers are fitted.
This guide is for general information only. It is not a substitute for a survey of your home or professional advice. Solar Help Centre does not install solar equipment or produce the final design for your home.
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