Do Solar Panels Work on Cloudy Days UK? (November 2024)

One of the most frequently asked questions regarding the installation of solar panels in the UK is whether or not they work on cloudy days, given that the UK is not especially renowned for its good weather conditions. Nevertheless, solar panels are still efficient and are being widely adopted nationwide to achieve the UK government's ambitious net zero by 2050 target.

In this article, we’ll answer all your questions about solar panel efficiency in cloudy weather in the UK, how to maximise solar panel efficiency under these adverse weather patterns, and how to find the most efficient solar panels for your household’s needs.

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Solar panels work in cloudy weather in the UK but with reduced efficiency. On cloudy days, they typically produce 10-25% of their normal output.

The impact varies based on cloud thickness and type; thin or partial cloud cover can allow more light through, sometimes even enhancing production through the "edge-of-cloud effect." While clouds decrease solar radiation reaching the panels, they don't completely block it, allowing for continued energy generation even in overcast conditions.

Atmospheric factors, such as aerosols (water vapour, dust, and air pollution), also reduce solar radiation. Seasonally, solar power generation drops significantly in winter to about 50% less of a typical summer day's output due to shorter daylight hours and increased cloud cover.

However, advancements in solar technology, which can be seen in the most efficient solar panels in the UK, can help improve performance in low-light conditions.

Moreover, while cloudy weather reduces solar panel efficiency, modern systems can still generate energy effectively. On overcast days, panels typically produce around 10-25% of their normal output, and strategies like spreading solar plants geographically can enhance grid resilience during such conditions.

Once the question of whether solar panels work in cloudy weather is settled, it’s important to consider “How can solar panels be maximised on cloudy days?” The short answer is that this will depend on several factors, such as the type of solar panels, the use of solar batteries to save surplus electricity, solar panel cleaning, and solar panel position.

In the diagram below, we’ve compiled the best tips to maximise solar panel efficiency on a cloudy day:

These adjustments can help maintain consistent energy production despite variable weather conditions, ensuring a more reliable solar power system in cloudy conditions.

Overall, solar panels can still operate effectively on cloudy days, although the UK's grey weather affects their efficiency. While performance can reach 80-100% on sunny summer days, it typically drops to 10-25% during overcast winter periods.

That being said, proper system sizing and orientation ensure that solar energy remains viable even in cloudy conditions. Rain can also help by cleaning the panels, potentially boosting efficiency. At the same time, by pairing your solar system with solar batteries, you can store surplus energy for later use.

Despite this variability, the advantages of solar panels still make solar energy a compelling choice in the UK. The government's commitment to renewable energy supports this, which is evident in its recent policy changes, including a significant increase in funding for renewable energy initiatives.

These include multiple solar panel grants such as the ECO4 scheme, which provides free panels to low-income households until 2026, while HUG2 offers up to £10,000 for eligible properties until 2025. The Smart Export Guarantee allows owners to earn money from exporting excess energy into the grid. Additionally, the  0% VAT scheme on solar panel purchases runs until March 2027.

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