When Is The Best Time To Install Solar Panels: A UK Guide

Last Updated on January 8, 2025

Autumn is the best time to install solar panels in the UK. But, why is this the case?

Find out all there is to know in this guide.

When Should You Install Solar Panels In The UK?

Autumn is the best season to install solar panels in the UK. This is because the autumn months – September to November – boast cooler temperatures, shorter wait times for installation and cheaper fitment fees.

Since photovoltaic (PV) panels generate energy from sunlight, the system uses light (not heat) to produce solar electricity.

Let’s take a closer look:

Favourable weather conditions

• Drier conditions: Autumn brings drier conditions, making it easier and safer for installers to work on your roof compared to wet winter months.
• Reduced rainfall: Autumn often experiences more stable weather patterns, allowing for uninterrupted installations. This can minimise delays and complications associated with bad weather.
• Lower temperatures: A solar system operates more efficiently at lower temperatures. While autumn has cooler temperatures than summer, this actually benefits solar panel performance. High summer temperatures can make it too hot for solar panels, reducing their efficiency by 0.5% for every degree above 25°C.

Optimal sunlight for energy generation

• Longer days: Although daylight hours decrease as autumn progresses, early autumn months still benefit from relatively long days. This allows for sufficient sunlight to maximise energy generation.
• Less intense sun: Solar panels function optimally at 25°C and with average autumn temperatures in the UK range between 10°C and 20°C, it’s ideal for solar energy production. 

Preparation for winter

• Energy storage: Installing solar panels (with battery storage units) in autumn allows property owners to harness the sun’s energy before winter arrives. This energy can be stored and used during darker, colder days.
• Lower energy bills: When solar installations are completed before winter, property owners can start benefiting from reduced electricity bills as they begin generating their own electricity.

Cheaper installation cost

• Out-of-season rates: While summer months allow solar panels to capture the most energy, it is the peak season for solar installations. This brings longer waiting periods and higher installation costs. Autumn months have the cheapest installation rates in the UK while still allowing for sufficient energy generation.
• Potential discounts: With fewer installations occurring during autumn, some companies may offer promotions or discounts to attract customers during the off-peak season.

Here’s a quick comparison between UK seasons so you can make a more informed decision:

Season	Rates	Installation speed	Solar power production	Installation conditions
Autumn (Sep-Nov)	Cheapest	Fastest	Sufficient	Good weather
Winter (Dec-Feb)	Cheaper	Faster	Least	Snow limits installation
Spring (Mar-May)	Cheaper	Faster	Adequate	Mild weather
Summer (Jun-Aug)	Highest	Slowest due to high demand	Most	High temperatures

What Are the Best Months To Install Solar Panels In the UK?

September to November are generally the best months to install a solar panel system as labour costs are much cheaper during the off-season. It’s not advised to install solar panels in winter due to inclement weather conditions.

However, warmer months, from March to August, are the most popular seasons to install solar systems in the UK. This is because they generate the most solar energy when there are 12 hours of sunlight per day. 

Need A Solar Panel Installation Quote?

Are you ready to install a solar energy system at your residential or commercial property? Request a free, no-obligation quote and start your renewable energy journey today – no matter the season!

FAQs

Does the weather affect solar panel installation?

Solar panels can be installed in most weather conditions, but heavy rain, snow, or strong winds may cause delays. Reputable installers will monitor weather forecasts to schedule installations during optimal conditions.

Do solar panels work in winter months?

Yes, solar panels work in winter. They are designed to capture sunlight efficiently, even on cloudy days. However, shorter daylight hours and weather conditions can affect solar energy generation, resulting in around 50% less energy production when compared to summer months.

At what temperature are solar panels most efficient?

Solar panels function at optimal efficiency at 25°C. The average solar panel system loses around 0.5% output efficiency for every degree above 25°C.

What is the solar bell?

The solar bell refers to the time of year when solar panels generate the most energy due to 12 hours of continuous sunlight. In the UK, this is between April and September.

How long does it take to install solar panels?

The installation process typically takes 1–3 days, depending on the size of the system and property specifics. Scheduling during less busy times of the year (e.g., winter) might mean faster service.

How does solar panel performance vary by season in the UK?

While solar panels generate more energy in spring and summer due to longer daylight hours, they still work efficiently in autumn and winter. Installing them early ensures you benefit year-round.

Final Thoughts

Autumn is the best season for a solar installation in the UK due to drier conditions and cheaper installation rates. By considering these factors and getting a free quote from Eco Happy, you can harness the sun’s power and enjoy the benefits of clean, renewable solar power for years to come.