It’s impossible to say exactly how much electricity your solar panels will generate. There are umpteen factors that must be accounted for – many of which are highly conditional – so an estimate of electrical output must be calculated case-by-case. To name a few of these:


Levels of light

To some extent, the more light that hits the solar panel, the greater the output of electricity. However, the weather is unpredictable at the best of times, and irradiance (the technical term for solar radiation) is distributed unevenly accross the planet. Even in the UK, there’s around a 32% difference in irradiance between Land’s End and John O’Groats.

UK Solar Irradiance


On top of your home’s whereabouts, how you position the solar panels makes a big difference. This includes the direction they face, the pitch of your roof, and the amount of shading. Most of this will depend on the suitability of your home.

Type of solar panel

Solar panels are put together in different ways, and different types are more effective at converting light into electricity than others. In other words, their efficiency levels vary. As a rule of thumb, the more you pay, the more electricity your solar panels will generate per square meter.


Solar panels gradually lose their efficiency over time, as the components naturally break down. This degradation rate is only minor though (about -0.5% efficiency per year).


The occasional clean will help to keep your solar panel working better for longer. You can find more on making your solar panels more efficient here.

Keep in mind that solar calculators can’t accurately predict how much electricity will be generated, but they’re a useful guide. For a more accurate estimate, call an MCS-certified installer to survey your home.


Do solar panels only work in the sun?

It’s a common misconception that solar panels need direct sunlight to work. It certainly helps to have sunny spells, but taking our usual grey and cloudy British weather into account, it’s a good thing it’s not essential.

Solar panels only require some form of light to run – even artificial light would produce a small amount of electricity, only not enough to be of use. That’s why solar panels are still able to produce a significant amount of electricity on rainy days and over the winter.

That being said, solar panels perform better over the summer as the days are longer. Electricity can’t be generated at night when there’s no daylight, but that doesn’t mean you have to spend your evenings in the dark. The energy that’s made during the day can be stored for later use with a battery.

Thinking about a solar installation?

If you want to install solar panels for your home, we can help. Just fill out our contact form. One of our Technical Account Managers will soon be in touch to discuss your project, before providing you with a detailed proposal complete with performance estimates and an initial quote.

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