Solar panels: how much of your electricity can they provide?

With bright sunny days and lots of midsummer daylight hours, solar panel owners can be smug in the knowledge they're using completely renewable power when the sun is shining. 

But how does their electricity generation work out over a whole year? We asked a panel of more than 2,000 solar panel owners* about their experiences.

Very few found that their solar panels could provide all of their electricity needs. But a quarter of those surveyed told us their panels generated between half and three quarters of their annual electricity. The rest they would get from elsewhere - usually mains grid electricity. 

Nearly 30% told us that their solar panels provided between a quarter and a half of the total electricity they needed over a year.

There's a huge seasonal variation in how much of your power solar panels can provide. Read our buying advice for solar panels to see how much of your power solar panels could generate in summer.

How much electricity does a solar panel produce?

Household solar panel systems are usually up to 4kWp in size. That stands for kilowatt 'peak' output - ie at its most efficient, the system will produce that many kilowatts per hour (kWh). 

A typical home might need 2,700kWh of electricity over a year - of course, not all these are needed during daylight hours.  

A few owners in our survey with smaller systems between 2.1kWp and 2.5kWp said that their panels generated as much as 2,700kWh over a year. 

However, some owners with systems twice the capacity reported that they produced the same amount.

That's because the specification in kWp of the system is the maximum, or 'peak', output it could generate in theory, rather than what your system will actually generate.

It's important to get some insights into how much power solar panels would produce on your roof before you decide how big a system you need. The total amount depends on several factors, including:

• your geographical location
• the season (and therefore hours of daylight)
• your roof's compass direction and slope
• any shading that might block the panels at certain times of day
• the efficiency of the system.

Note that without an accompanying battery, you can only use solar electricity as it's being generated. When you want to use it might not match with when when your solar panels are generating.

For example, your panels won't be producing power when it's dark and you want to switch on the lights or other appliances on a dark winter evening.

However, many owners find they can be flexible with their electricity use to maximise the amount they can get from their panels — running large appliances during daylight hours, for example. 

Find out if solar panels are worth it for you.

Can I be self-sufficient with solar panels?

The UK isn't famous for its bright sunshine, but the sun doesn't have to be shining for solar panels to work. Even on overcast days, the UK has enough sunlight for solar panels to work. They'll produce some electricity in winter, although the shorter the days are, the less you will get.

Whether they'll generate enough electricity for your home year-round will depend on:

• how much power your solar panels generate
• whether they generate enough electricity in winter
• how much power your home needs, and when you need it
• whether you're able to use the electricity generated or store it in a battery until you need it
• if your solar panel system works in a power cut.

It may be more realistic to think about whether you can be self-sufficient for the brighter parts of the year, and then top up your energy use from the grid at other times.

How to use more of your solar power

Adjusting your routine to use more power at the times your solar panels are generating it is a quick way to benefit from more of your solar electricity without having to invest in a battery.

Check our tips to make the most of your solar panels from solar experts and owners. 

But this might not be feasible if you're usually out during the day.

Installing a battery alongside solar panels means you can store excess electricity generated by your solar panels to use at a time that suits you. 

Two-fifths of solar owners in our survey also had a battery that stores electricity for later use. 

Find out more about solar panel battery storage. 

*We surveyed 2,039 solar panel owners who are part of our Which? Connect member panel in April 2024.