Mounting Solar Panels on a Wall: An In-Depth Guide

Back Nikola Nedoklanov 7 min read April 4, 2024 1430 words

Harnessing the Sun: Detailed Guide to Wall-Mounted Solar Panels in the UK – Installation Tips, Advantages and More

Artistic illustration for a blog post titled 'Mounting Solar Panels on a Wall in the UK: An In-Depth Guide'. Feature a single, sleek solar panel mounted on a brick wall, with abstract art motifs symbolizing sustainable energy and innovation. The background should have a gradient from deep blue to soft green, representing the blend of technology and nature. Include subtle elements that suggest the detailed aspects of the installation process, like tools and measurement lines, in an abstract and conceptual manner.

Home solar energy system owners in the UK have traditionally focused on installing panels on rooftops. However, wall mounting offers an alternative for properties with unsuitable roofs due to structural issues or shading. This guide explores regulations, considerations, and the practicalities of wall-mounted solar panels.

In This Article:

Can I Install Solar Panels on a Wall?

Yes, it is fairly common and has advantages and disadvantages. On top of being an alternative to a roof, walls are viable expansion places.

A solar panel on a wall, low sun is hitting most of the panel. — Installing solar panels on a wall can help with improving solar harvest during the winter.

Planning permission

According to the planning portal, installing solar panels and equipment on residential buildings falls under permitted development.

Mandatory Limits Apply

In an elaboration of the requirements, the planning portal offers a list of mandatory requirements concerning roof and wall-mounted solar panels.

Panels should not be installed above the highest part of the roof (excluding the chimney) and should project at most 200mm from the roof slope or wall surface.
Do not install the panels on a listed building’s grounds or a scheduled monument site to preserve their historical significance.
If your property is in a conservation area or a World Heritage Site, panels must not be fitted to a wall which fronts a highway.

These rules are general, and stricter local permission requirements may override them. Make sure to confirm with your local authority before you start your project.

Weight Considerations

The wall’s structural integrity is crucial to support the weight of the solar panels and mounting equipment. This might necessitate an engineering assessment and potential reinforcement, particularly for older buildings.

Advantages of Wall-Mounted Solar Panels

For year-round production, mounting panels on walls is not optimal. The 80°-90° angle places them at a disadvantage during significant parts of the year. Especially the summer months when we have the best potential for harvesting solar energy in the northern hemisphere. However, near vertical panels are not without advantages.

Space Optimisation

For properties with limited or unsuitable roof space, walls present an alternative installation surface. Thus keeping the roof surface for other uses or entirely away from it. For example, your roof is quite old and potentially not as sound as it was. However, you think it has a few years left in it before a major repair is needed. Therefore, you don’t want to mount panels on it and cause damage or have to remove the panels when you repair it.

Efficiency Considerations

While wall-mounted panels are generally less efficient than roof-mounted ones, they can be viable in certain scenarios. South-facing walls offer the best sunlight exposure. The tilt and direction of panels are crucial for optimising efficiency, with a 60-degree angle ideal for capturing low winter sun.

Winter Sun Capture

Vertical panels can be more effective at capturing low winter sun. The further north you are, the more pronounced this seasonal benefit. In the UK, the winter sun is relatively low and energy usage typically increases during winter. Therefore, wall-mounted panels can be particularly beneficial here.

Without projecting a panel beyond 200mm from the wall, from the wall, you can mount a typical panel with dimensions 170cm by 110cm at around 80°.

Diagram showing the output of a flat solar panel. Barchart. — A wall-mounted panel gives much better consistency and peaks in spring and autumn compared to the summer. Yearly production ~290kWh.

Practical Aspects of Installation

There are multiple options for mounting panels on a wall. I will outline some options and share my experience mounting eight panels on a vertical wall for a DIY project.

Specialised Wall Brackets

There are purpose-built solutions on the market for mounting solar panels on walls. These are costly, and you need to buy them for each panel.

The added cost is an important consideration.
However, the advantage of these systems is that you can angle your panels more easily, as this functionality is built-in. The ease of adjusting the mounting angle can help you increase your energy production throughout the year.

Tilt Angle	90°	80°
PV installed [Wp]:	400	400
Yearly PV energy production [kWh]:	291.86	330.35

As you can see from the table above, reducing the angle by 10° gives us an additional ~40kWh of energy a year. For reference, the optimal tilt angle for the panel in this situation is 40°.

Mounting Solar Panels on Unistrut Rails

Unistrut rails provide secure and adjustable mounting solutions for various wall types and materials. Another advantage of Unistrut rails is that they are a cost-effective solution with proven longevity. It is universally available from local electric supply wholesalers, too. Additionally, fittings, angles and other available accessories can turn this into a customised solution that fits your project.

Photograph of unistrut rails installed on a wall. The wall is brick there is nothing on the unistrut rails yet. — Unistrut rails are sturdy steel rails with prefabricated clamping grooves on the inside and mounting holes at the back. Here, we see an example of mounting them on a wall.

Clamps for unistrut

Solar panel clamps for unistrut are cheap, easy to work with and just as widely available. However, there is a specific difference between these clamps and most roof mounting system clamps. The Unistrut clamps have end and middle clamp flavours. Unlike other systems, you cannot use the middle clamps as end ones.

Photograph of unistrut end clamp. — End clamp coupled to a Unistrut nut.

Using Fastensol Clamps with Unistrut Nuts

On a relevant DIY project, we used Fastensol clamps and replaced their nuts with M8 unistrut nuts. The total price of a clamp was reasonable, going around £1.5 a piece. Here are some links to see what the clamps look like:

Photograph of Unistrut end clamp on a panel installation. The end of the rail is visible. And an close-up of the unistrut nut. — The Unistrut nut slots into special grooves on the inside of the rail for extra protection against sliding.

Vertical Slip

Here is the inside of the Unistrut rail alongised the stud nut. These nuts are sold for unistrut but you can fit them on the solar panel clamps easily. You can see that vertical slip is nigh impossible when fastened tightly.

DIY Working at Heights and Lifting Panels

Installing solar panels on a wall is a relatively simple DIY project. It is, however, a job for the more experienced DIYers. It requires capable power tools for drilling into the masonry and experience in fixing heavy objects.

Working at Heights

For safe and efficient installation, you can use a scaffolding tower. You can hire one of these for less than £200 a week. In my experience, it isn’t a fast DIY job. Hiring for a week should give you a comfortable time frame to fit the panels on the wall. Scaffolding towers are lightweight and easy to build, and most vendors deliver and collect from your home.

Mounting Solar Panels on Fences and Boundary Walls

Innovative solutions often arise from the need to maximise space utilisation. An emerging trend in home solar energy is the mounting of solar panels on fences and boundary walls. This ingenious approach capitalises on unused vertical space. Additionally, it offers a host of advantages, ranging from amplified energy production to elevated property aesthetics.

Eco-friendly residential wooden fence integrating uniform solar panels throughout, demonstrating sustainable energy solutions in home design

Risks of Placing Solar Pnales On A Fence or Boundary Wall

Almost everything about mounting panels on a wall applies here, too. A stark difference here is that fences and boundary walls are at a higher risk from damage. This can come from wind or other intrusions such as debris or even cars. Therefore, not all fences are suitable for hosting solar panels.

Nevertheless, the constant drop in prices of solar panels stimulates creative thinking on where else homeowners might place some more of them.

Conclusion

Wall-mounted solar panels offer a viable alternative for UK properties with unsuitable roofs. While specific considerations regarding installation, regulations, and efficiency exist, they present an innovative way to harness solar energy, especially during winter. Consulting with professionals is recommended to ensure a safe and compliant installation.

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