The number of solar panels you need ultimately depends on how much electricity you want to generate.
Most domestic systems have a capacity of between 1 kilowatt (kW) and 4 kW. Larger‑capacity systems are more productive—and will save you more money—so you should get the biggest system you can for your home.
Most homes in the UK have roofs that can accommodate solar panels. However, if your roof has a window, chimney or vertical flue, this could reduce the amount of space you have for a solar panel system.
For an idea of overall size:
Bear in mind that some brands of panel have a larger capacity so may cover a smaller area of roof space.
How big is a solar panel?
There are many brands of solar panel, and each brand is slightly different in size. However, on average, one standard solar panel will be approximately:
A solar panel is made up of a series of small photovoltaic (PV) cells wired together. Most domestic systems use solar panels that have 60 of these cells.
The full system (known as an array) consists of a number of solar panels, typically placed next to one another.
Step 3: Ensure your roof can bear the weight of your chosen system
There will be some variation between brands as to the weight of a single panel, but the standard 60‑cell solar panels used in most residential systems weigh 18 kg–20 kg.
Most homes have roofs that can easily support this weight, although an installer would determine this—and whether any work is needed to strengthen the roof—as part of their initial inspection.