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Flat Roof Solar Panels – Do They Work?

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do flat roof solar panels work?

UK households and commercial businesses are naturally looking for ways of reducing their carbon footprint and energy bills by choosing sustainable energy sources as an alternative. This has led many, who are considering solar panels as a means of generating their own electricity, to ask if solar panels can be installed on a flat roof? The answer is usually a yes, but this will depend on a few factors relating to the flat roof itself, including its location.

While there are many things to think about when installing flat roof systems, it’s a popular choice for both business and residential properties. Flat roofs are a good option for a solar panel array, and they can also house solar thermal systems.

While planning permission for pitched roof solar panels is not required in most areas, the planning rules can be a bit different when it comes to solar panels for flat roofs in the UK. It is always best to seek the advice of your local planning authority (LPA) before making any firm plans to ensure you are following all official guidelines.

Dismissing Misconceptions About Flat Roof Solar Panels

Many homeowners with flat roofs don’t even consider installing solar panels on their flat roof because they mistakenly believe their roof space does not receive enough direct sunlight to justify the expense. However, in many cases, installing solar PV panels on a flat roof can be completely feasible.

While solar panels on flat roofs are more commonly seen on commercial structures, they are still an option for residential properties. Find out how flat roof solar panel systems work, the benefits of using one, and how you can maximise performance and longevity of your solar panels.

How do Solar Panel Systems Operate on a Flat Roof?

Flat roof solar panels are most commonly seen on commercial buildings, which typically have flat roofs. However, because of their versatility, they can also be installed on residential properties.

A solar array on a flat roof uses the same type of solar panels as a standard system, but the mounting systems used have to to be specific to flat roof systems. Additionally, there are some other considerations that have to be taken into account to ensure the performance of the solar panels is maximised.

Solar panel installers should also consider the angle at which the system is positioned to capture the most amount of solar energy possible. Thin film solar cells have the potential to be quite useful in this situation. They feature a high degree of adaptability and can even be converted into self-contained panels.

These move with the sun throughout the day, ensuring that they receive the most sunlight possible by remaining in direct sunlight as much as possible.You would be able to generate more power throughout the day with an automatic system as opposed to a fixed one, even though the efficiency of automatic systems is lower than that of crystalline solar panels.

Flat roof installations will also need to take into account the elements. Rain can actually aid your solar panels by self-cleaning them when the water runs off them. The Mounting system must also be secure and robust enough to withstand severe gusts.

What Are The Benefits Of Installing Solar Panels On Flat Roofs?

There are a number of specific advantages or benefits that result from installing a flat roof system:

  • Because the area is flat and easier to access than a typical pitched roof, installation and maintenance are simplified and less expensive.
  • Once installed, the panels are less apparent at street level, so they won’t impact your home’s appeal or cause issues with your neighbours.
  • You can choose from a variety of solar panels which will give you a more environmentally friendly and sustainable form of energy (and therefore reduced carbon footprint).
  • When compared to a pitched roof, there are more design and layout alternatives for effective panel location.

 

Solar panels can increase the value of your property, if you are looking to move on in the near future. Alternatively, if you stay put, you can start reaping the benefits of solar renewable energy and fully utilising your flat roof.

Do You Need Planning Permission to Install Solar Panels On A Flat Roof?

In truth, solar panels for flat roofs in the UK can sometimes be a little problematic when it comes to required planning permission. Ordinarily, solar panels on a pitched roof are considered ‘permitted development’ and therefore planning permission is not usually required, but with flat roofs things can be different.

Because flat roof solar panels need to be placed in special mounting frames to achieve the right angle towards the sun, this means they protrude more than 0.2 metres above the roof slope, putting them outside the permitted development guidelines.

Planning approval for flat roof solar panel installation will also usually be required if they are being sited on a listed building or in a Conservation Area. Before beginning any type of flat roof solar systems work, you are strongly advised to contact the Local Planning Authority to confirm that you are following all of the necessary procedures.

Creating A Flat Roof Solar System Panel Array

Whereas solar panels on a pitched roof are able to just follow the orientation and pitch of the roof, solar panels can be added to a flat roof at a specific pitch for improved efficiency. This is ideal if you have a sizeable flat roof space to work with, but it might be difficult if you are working with a smaller or irregularly shaped flat roof.

Most solar panels are intended to be self-cleaning and for this reason, the solar panel array must be pitched in order that any dust, dirt or debris is able to run off during rainfall, as well as enabling the solar panels to capture the most UV radiation from the sun.

The design must also guarantee that panels are not overly shaded by nearby aspects such as trees, chimneys, higher structures, or air con units, which are commonly found on the roofs of commercial buildings.

Other factors to consider when putting solar panels on a flat roof that do not apply to pitched roofs include optimal pitch, wind considerations, and orientation.

What Angle Must Solar Panels Be Set At On Flat Roofs?

Solar panels installed on flat rooftops should normally be orientated to receive the maximum amount of sunlight throughout the day. An incline of at least 10 degrees is essential to ensure that rain is able to wash away dirt and debris from the surface, keeping the efficiency levels as high as possible.

Most installers will choose an A-frame as the mounting technique of choice when mounting panels at an angle ranging from 20 to 50 degrees. A qualified and experienced installer will be able to determine the best pitch for placing solar panels on your flat roof.

How To Reduce The Risk Of Damage From Strong Winds

Unsecured or improperly installed solar panels can be at risk due to strong winds. To limit the risk, it is critical that your solar panels are fitted by the right method.

There are two major methods for attaching solar panels to flat rooftops to ensure their safety under extreme weather conditions:

1) The first alternative is to include the solar panel frame into the roof structure below the roof line, implying that fittings will pass through the exterior roof membrane layer.

Although this technology results in a secure solar panel system, it can be costly due to the need for specific fittings and the risk of compromising the roof’s waterproofness. Penetrating the surface of the may also void the manufacturer’s guarantee on your roof.

As a result, this solution is usually employed on new build roofs, where the solar panel fittings may be included in the initial roof construction and will cause the least disruption to the roof installation.

2) The second approach, and possibly the most commonly used, is to install solar panels on an existing flat roof using weighted frames.

Concrete slabs or stone chippings are used to tie the panels to the roof, while rubber feet on the frames distribute the weight evenly throughout the roof’s surface.

This alternative is simpler because it does not interfere with the roof’s integrity. However, if your panels have a steeper pitch, the amount of ballast required to anchor the panels may become overly heavy for your roof structure.

In either case, it is important that you talk with both your roofing specialist and solar panel installer to make sure your roof design and solar panel layout are compatible and will provide you with efficient solar panels.

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Oliver Creevy
Ollie Creevy has over three years of expertise in the home improvements and solar panels sectors by writing content across multiple websites. He is highly knowledgeable about the latest trends, technologies and practices in this industry, and is passionate about sharing his insights with others. Ollie's writing has been featured in numerous publications, including MSN, Bustle, and Realtor.com.

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