How to Install a Solar PV System on Your Roof

It can often take two to three days to install a solar PV system on your roof. In addition, if your building has more than one storey, you will first need to erect some scaffolding.

You should also ensure that the solar PV fixing system is able to support the weight of the panels in all types of weather, especially during periods of intense winds. The system must also be able to tolerate varying temperature ranges and it should be installed in such a way as to prevent water from coming in through the roof. 

Here are the recommended ways to install a solar PV system on your roof.

Retrofit the PV panels on your existing roof

Installers can retrofit your existing roof to accommodate the solar PV panels. Roof anchors, mounting rails and clamps are usually the materials used in this method of installation.

A typical mounting rail will be mainly composed of aluminium, while some of its components will be made of stainless steel.  

A locking system is used to fix the mounting rails to the roof anchors while clamps will secure the panels to the mounting rails. 

What will you need?

1. Roof anchors

The installers will determine which type of roof anchor to use based on your existing roof tiles, while also taking account of the height and spacing of the roof battens. 

If your roof has thick or ridge tiles, the roof anchors will often be fixed to the rafters. This process involves the lifting and replacement of the affected tiles.

If you have a slate roof, the roof anchors can be drilled through the slate to the rafters. As this is quite a delicate process, you will need to hire professional installers to carry out this work. The area around the roof anchors should be sealed to avoid water penetration. 

The installers should never fix the roof anchors to the tiling battens as they will not be able to bear the extra weight of the solar PV panels.

1. Anti-theft fixings

Besides taking account of the local climate, you will also need to consider the possibility of theft. In this regard, you can ask your installers about incorporating anti-theft fixings, which can include:

• Security bolts that can only be unfastened with a special drill bit
• Bolt heads with a serrated edge so it would be difficult to cut them off
• An alarm system integrated with the PV panels with plastic optical fibre 
• Security markings on your PV panels (e.g., your postcode)
• Lighting around the PV system 
• Strategically placed PV panels to prevent potential thieves from gaining access (or at least making it more difficult)

If you are arranging building insurance, you should ensure that it will cover lost or damaged PV systems. Ideally, you should contact your insurer and obtain confirmation before having the panels installed.

Integrate the solar PV system on a new roof

If your house or building is new or being re-roofed, a roof-integrated solar PV system would be the way to go. As mentioned earlier, the type of roof fixing will depend on your choice of PV. 

Installers can fix solar tiles to the battens using large starter hooks along the first row. They may also counter-batten before installing the panels to improve the ventilation and keep the roof cool. 

Another roof-integration method involves the use of frames to support the panels so they can be fixed directly to the rafters. A flashing kit is used to waterproof the roof.

Installation on flat roofs

If you have a flat roof, installing solar PV panels will provide you with more electricity if they are angled towards the sun. Installers will often use an A-frame mounting system or a plastic tray at an angle of 15o from the horizontal, improving the performance of the panels while reducing the visual impact and wind load. A lower angle will also reduce the risk of one row casting a shadow on another.

As the panels will be situated above the roof, you may need to apply for planning permission. 

Most installers will avoid making holes in the roof due to the risk of leaks. Instead, they will use a fixing system that will weigh down the panels with ballast, such as paving slabs or gravel. This will keep the solar PV panels firmly in position without having to penetrate the roof.

You will need to hire MCS-registered installers who will determine whether your roof structure can carry the weight of the solar panels and mounting structure. If there is any doubt about the soundness of your roof, you may have to arrange a structural survey. However, this could entail the removal of a small portion of your ceiling to check the joists. 

Mount panels on the ground

If it is not possible to install a mounting system on the roof due to the visual impact, wind load or any other relevant concerns, you may have to consider a ground-mounted system. Here, the solar panels are fixed using an A-frame or other suitable framework. The process is similar to a roof installation except that the system is fixed on the ground.

Installers will use concrete piles or raft foundations to fix the solar panels to the ground. They can also use the rammed earth technique or ground screws to reduce the environmental impact.

Your installers will decide on the best method based on the following factors:

• Existing ground conditions
• Framework type
• Weight of the panels

Regardless of the fixing method employed, a trench will be needed to bury the DC cable from where the inverter is sited.

Use a tracking system

Solar PV tracking systems can move the panels so that they will follow the sun, thereby enabling them to produce around 30% more electricity compared to static panels.

Understandably, tracking systems are more expensive, which may outweigh the potential increase in electricity production for most residential solar PV systems. Nevertheless, if you are planning to install a large-mounted system, you can discuss the possibility of adding a tracking system with your installers. 

Ensure the roof and wind load complies with the local building regulations

You will need to check the provisions of the local building regulations to ensure your solar PV system will be structurally sound. If the load on your roof increases by 15% or more or if there is going to be a substantial alteration, you may need to obtain official approval.

Conclusion

At Kingsley Roofing, we have extensive experience of providing roofing and electrical services, and as such we can offer our customers complete solar panel solutions. We can also offer a variety of bespoke solar roofing installations. Furthermore, we use the latest technology to provide homes and businesses with clean energy at a reduced cost.

If you have any questions about solar panels, please get in touch with one of our team. We will be happy to discuss your requirements and provide you with a quotation.