Do Solar Panels Need Direct Sunlight?

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Last Updated on 24th September 2024

Do Solar Panels Need Direct Sunlight To Work In The UK?

In short, no, solar panels do not need direct sunlight to generate electricity. In fact, they can produce power in various lighting conditions, including cloudy and overcast days.

While solar panels can generate electricity in many weather conditions, it's important to note that their efficiency is highest during periods of direct sunlight and they are unable to produce any power at night when no light is available.

In this article, we'll look at how solar panels use light to generate electricity, the importance of correct solar panel positioning and how you can optimise your solar array when direct sunlight is limited.


How Solar Panels Convert Light Into Electricity

Solar panels convert light into electricity through the photovoltaic effect, where photons from sunlight excite electrons in silicon cells, creating an electric current that is then captured and converted for use in homes and businesses. However, this does not have to be direct sunlight because solar panels can also utilise diffuse light that is scattered by clouds, atmosphere and surrounding objects.

As already mentioned, this ability to harness both direct and indirect sunlight allows solar panels to generate electricity even on overcast days, though their efficiency is reduced compared to bright, sunny conditions.

What Is Diffuse Light?

Diffuse light is light that is scattered or spread out evenly rather than coming from a single direct source. It occurs when light is reflected or refracted by particles in the air, clouds or other surfaces that cause it to scatter in many directions.


How Efficient Are Solar Panels Without Direct Sunlight?

As we've covered, solar panels can still generate electricity without direct sunlight but their efficiency is reduced. On cloudy days, solar panels typically produce 10-25% of their normal power output.

Though, this reduction in efficiency varies depending on the thickness of cloud cover and the quality of the solar panels.

It's important to understand that the efficiency of solar panels in non-direct sunlight conditions can be influenced by several factors:

  1. Panel quality: High-efficiency panels and those made with monocrystalline silicon tend to perform better in low-light conditions.

  2. Cloud density: Thicker cloud cover, as mentioned above, will result in lower efficiency than light, scattered clouds.

  3. Time of day: Even on cloudy days, midday hours typically provide more light than early morning or late afternoon.

  4. Panel positioning: Properly angled panels can maximise the capture of available light.

While solar panels are less efficient without direct sunlight, they continue to generate electricity in various light conditions, making them a viable energy solution even in areas with frequent cloud cover.


What Is The Ideal Solar Panel Positioning?

The ideal positioning of solar panels is crucial for maximising their efficiency and energy output. In the UK, the best orientation for solar panels is south-facing as this direction allows them to capture the most sunlight throughout the day. Panels facing south can generate significantly more electricity compared to those facing other directions, though east and west orientations are still viable options.

When it comes to angle, the optimal tilt for solar panels in the UK generally falls between 30° and 40°. This angle enables the panels to absorb sunlight effectively throughout the year.

Consulting with a professional installer, such as Glow Green, can provide tailored advice on the best positioning for your specific location and roof type.

You can also read our guide on 'is my roof suitable for solar panels?' for more information.


Is The UK's Climate Suitable For Solar Generation?

Contrary to popular belief, the UK's climate is well-suited for solar panel efficiency. While solar panels do perform optimally in direct sunlight, they can still generate significant electricity in the UK's varied weather conditions.

  • Moderate temperatures: The UK's generally mild climate is advantageous for solar panels. In fact, the UK's cooler temperatures can be beneficial compared to hotter climates where excessive heat can lead to efficiency losses.

  • Ample sunlight: Despite its reputation for grey skies, the UK receives sufficient sunlight for solar panels to function effectively. The country gets about 60% of the solar radiation found at the Equator with some southern areas receiving comparable sunlight to parts of Germany, a leading market for photovoltaics.

  • Seasonal variations: While summer months naturally produce more energy due to longer daylight hours and higher sun angles, the UK's climate allows for year-round solar energy production. Modern solar technologies are designed to take advantage of peak summer production to balance out lower winter output.

  • Rainfall benefits: The UK's frequent rain, often seen as a drawback, actually helps maintain solar panel efficiency by naturally cleaning dust and debris from their surfaces.

Ultimately, our climate offers a balanced environment for solar panels, combining moderate temperatures, sufficient sunlight and natural cleaning mechanisms.


Strategies For Solar Panel Optimisation

While direct sunlight is ideal for solar panels, there are several strategies to optimise their performance even in less-than-perfect conditions:

  • Smart inverter technology: Upgrading to smart inverters with maximum power point tracking (MPPT) can significantly boost panel efficiency. These devices optimise the performance of individual panels which reduces the impact of shading and panel mismatch.

  • Panel cleaning and maintenance: Cleaning solar panels can improve their efficiency especially after periods of dry weather or in areas with high pollution.

  • Tilt angle optimisation: As mentioned above, ensure your solar panels are positioned correctly according to your location.

  • Solar concentrators: Consider using mirrors or reflective surfaces to redirect additional sunlight onto your panels. This technique, known as solar panel reflector systems, can increase exposure to light and boost overall energy production.


The Role Of Battery Storage In Low-Light Conditions

When solar panels are not producing power due to adverse weather conditions, such as heavy cloud cover, intense storms or during nighttime hours, battery storage systems step in to ensure a consistent supply of electricity. These innovative energy storage solutions act as a buffer storing excess energy generated during peak sunlight hours for use when your solar panels are less productive.

For instance, on a string of overcast days or during extended periods of rain, your stored energy can power your home which maintains your energy independence.

By integrating battery storage with your solar panel system, you create a more resilient and efficient energy solution that maximises the benefits of solar power, regardless of immediate sunlight availability.

For more information, you can read our guide on battery storage costs and prices.


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Do Solar Panels Need Direct Sunlight FAQs

Do solar panels need direct sunlight to generate electricity?

Solar panels do not require direct sunlight to produce electricity as they can generate power from indirect sunlight as well. Even on cloudy or overcast days, solar panels can still capture diffuse sunlight and convert it into energy although their efficiency may be reduced.


What conditions are best for solar panel performance?

Solar panels perform best in moderate temperatures with clear skies and direct sunlight. However, they can still function efficiently in cooler temperatures which can enhance their overall performance by preventing overheating.


Can solar panels work in winter?

Yes, solar panels can work effectively in winter. While shorter daylight hours and potential snow cover may limit their output, they still generate electricity from available sunlight.


How do shading and obstructions affect solar panel efficiency?

Shading from trees, buildings or other obstructions can significantly reduce the efficiency of solar panels. Even partial shading can cause a drop in energy production due to the way solar cells are connected in a series. Using microinverters or power optimisers can help mitigate these effects.


How can I maximise my solar panel's energy production without direct sunlight?

To maximise energy production without direct sunlight, consider optimising your panel's tilt angle, use reflective surfaces to enhance light exposure and ensure that your installation location is free from obstructions that could cast shadows.