Solar Panel Efficiency

The majority of solar panels on domestic systems in the UK are around 10-20% efficient. Whilst this might sound like a low figure, a 4kw system could actually generate enough electricity to dramatically reduce your energy bills and carbon emissions. How efficient a panel is can be impacted by factors like its position on the roof, the efficiency of the system’s inverter and the type of material it is made of.

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What Affects the Efficiency of Solar Panels?

There are a few main factors that affect the efficiency of your solar panels. Most of these should be considered before you have the system installed and a reputable solar installer will be able to advise you on the best options for your home.

Just a small amount of shade on a solar panel can have a big impact, in fact some reports suggest as little as just 10% of the panel being in shade can reduce its efficiency by up to 50%! Before installing solar panels on your home, the installer should carry out a shading analysis to evaluate any potential issues from obstructions like chimneys or trees.

Panel placement
In the UK it is recommended that solar panels are installed on south facing roofs for optimum efficiency. Whilst they can be placed on some East and West facing roofs, the output levels are a lot lower.

Roof pitch
The pitch, or angle of your roof can affect the number of hours of sunlight your panels receive in a day. For this reason it’s important to consider the pitch of your roof before installation. The best pitch for domestic solar arrays in the UK is around 30-45 degrees.

Whilst regular rainfall can clean solar panels, occasionally they may need cleaning more thoroughly to remove any bird droppings or dirt that could be reducing efficiency. The easiest way to go about this is hiring a professional as they will have the experience and equipment to carry out the cleaning safely.

Solar panels are designed to collect energy from the sun, but they can actually see a reduction in efficiency when they get too hot. This generally shouldn’t be a problem in the UK as we rarely see high enough temperatures to cause any issues.

How is Solar Panel Efficiency Measured?
Efficiency is expressed as a percentage reached by a simple equation. The Eco Experts explain it as ‘the ratio of incoming sunlight to power out of the panel, expressed as a percentage.’ The majority of domestic solar PV panels in the UK have an efficiency level of between 10-20%.

Which Solar PV Panels are the Most Efficient?
This varies across different manufacturers and models, but most suppliers will provide you with a figure for the efficiency of their panels. Monocrystalline panels tend to have a higher level of efficiency than polycrystalline silicon however they are also more expensive so it is a consideration you should weigh up thoughtfully.

The best way to ensure your solar PV system is as efficient as possible is to have an MCS certified and experienced solar installer assess your needs, which you can find using Solar Guide.

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