Solar photovoltaic panels can reduce your energy bills, but how many solar panels can pay for your electricity and your roof?

Solar panels can reduce your carbon footprint and reduce your energy bill by providing almost all the electricity you need. But solar photovoltaic devices are not one size fits all. How many solar panels do you need to meet your electricity needs in the UK? Is your roof and budget big enough?

Solar panels are a smarter investment than ever for families of all sizes. Solar devices soared 80 per cent last year alone, amid surging energy costs and falling panel costs, with about 2 million British households reportedly planning to follow suit next year. Solar suppliers suggest that the average roof area required is 20 square metres and can hold 10 panels at a cost of about £6000, but many homes can use solar energy with fewer panels.

How big solar panel sizes uk does the average house need?

The average 3.5kWp (kilowatts peak) solar PV system in the UK comprises 10 standard 350W panels, each of which measures 1m x 2m (2m²), with this average installation taking up 20m² of roof space (about 4m x 5m).

Given a sunny south-facing spot in typical UK conditions, that 10-panel array will produce around 2,645kWh (kilowatt hours) of energy per year. That, according to Ofgem, is nearly enough to cover the 2,900kWh of electricity used by the typical British household in a year. In other words, the average 10-panel installation will be sufficient to cover all the electricity needs of the average household.

How do I work out how many solar panels I need?

First, calculate how much electricity you want your panels to provide. Again, this is down to much more than just the size of your home. You will need more solar panels if your electricity needs are high (say, your whole family works from home), or if your house isn't well insulated.

Your energy bills or provider can tell you exactly how much electricity you consumed last year, measured in kWh. Alternatively, get an estimate of your annual usage by using a free online calculator that takes into account your thermostats, insulation, electrical appliances and more. Then, compare that figure with the average energy output rates of different-sized systems in the table above.

When translating your energy needs into solar panel numbers, remember that a typical 350W solar panel produces around 265kWh per year in the UK. So if you use 2,650kWh of electricity annually, you can theoretically provide it all with 10 solar panels. If you only use 1,500kWh or less, then a six-panel array will be sufficient for your needs.