Solar panels are a popular, sustainable and cost-effective solution for generating cleaner electricity and reducing your energy bills.
If you’re considering adding solar panels to your home, you’ll likely encounter two main types of installations: in-roof and on-roof systems. Understanding the differences between these options will help you make an informed decision about which is best for your property, and that’s what this blog is about.
On-roof solar panels
On-roof solar panels are the most common type of installation you’ll see on homes across the UK. They’re mounted on top of your roof tiles or slates, creating a slight protrusion from the roof surface.
The installation process for on-roof panels is relatively straightforward. Mounting brackets are attached to your roof rafters, and rails are fixed to them. The solar panels are then clamped onto the rails, sitting a few inches above your roof tiles.
On-roof systems offer several advantages. They’re typically less expensive to install than in-roof systems and can be easily added to most existing roofs without significant modifications. They also allow for better ventilation behind the panels, which can improve their efficiency.
However, on-roof panels do have some drawbacks. They’re more visible from the ground, which some homeowners find less aesthetically pleasing. They can also be more susceptible to wind uplift, although this is rarely an issue with properly installed systems.
In-roof solar panels
In-roof solar panels – also known as integrated or built-in solar panels – are designed to sit flush with your roof tiles. Instead of being mounted on top of your roof, they become part of your roof structure.
The installation process for in-roof panels is more complex. It typically involves removing a section of your existing roof tiles and replacing them with the solar panel system. The roof is first prepared with a breathable membrane and wooden battens, or lats. The solar panels are fitted directly onto these lats, with special flashing kits used to ensure a watertight seal around the edges. Because of this extra work, in-roof panels are often better suited to new roofs or extensions, as they can be built in at an early stage rather than retrofitting into an existing roof.
There are different in-roof systems available, each with a specific installation method. For example, the Virident Solar system (also known as the Marley roof system) involves panels that click together and are screwed directly to the roof lats. Other systems, like the GSE system, use special trays or ‘buckets’ that are installed in place of some roof lats.
Key differences between in-roof and on-roof systems
The most apparent difference between these systems is their appearance. In-roof panels sit flush with your roof, creating a sleeker, more integrated look. On-roof panels, while still attractive, are more noticeable. Installation methods also differ. On-roof systems can usually be installed without major changes to your existing roof structure. In-roof systems, on the other hand, become part of your roof and require more extensive work during installation unless they’re being fitted to a new roof with no existing tiles.
When it comes to cost, on-roof systems are typically less expensive to install. However, for new builds or roof replacements, in-roof systems can be cost-effective as they replace a section of your roof tiles, so you won’t need to pay for tiles that will be covered by solar panels.
Choosing between in-roof and on-roof solar panels
Your choice between in-roof and on-roof solar panels will depend on several factors. For new builds or extensive renovations, in-roof systems can be an attractive option. They integrate seamlessly with your roof design and can be more cost effective when factoring in the savings on roof tiles. For existing homes, on-roof systems are often the more practical choice. They can be installed with minimal disruption to your current roof and are generally less expensive.
Your roof’s condition and type will also play a role. Some older roofs may not be suitable for in-roof systems without significant reinforcement. The pitch of your roof can also influence which system is more appropriate.
Budget is, of course, a key consideration. While in-roof systems may have higher upfront costs, they could add more value to your property due to their sleeker appearance. Because they’re integrated into your roof structure, they’re less exposed to the elements than on-roof panels. This can potentially extend their lifespan and reduce the risk of weather-related damage. The flush fitting also means there’s less chance of debris accumulating under the panels, which can be a problem with on-roof systems.
For new builds, extensions or full roof replacements, in-roof systems can offer unexpected cost savings. While the initial installation cost might be higher, you’ll save money on the roof tiles that the panels replace. Over a large roof area, your savings can be substantial. For a typical domestic installation, this could mean 400-500 fewer tiles to purchase. Opting for an in-roof system from the start can be more straightforward than retrofitting solar panels later. It allows for seamless integration with your construction project, ensuring that your roof is designed and built with solar in mind from day one.
In-roof systems also tend to be more versatile when it comes to roof shapes and sizes. They can often cover a larger percentage of your roof area than on-roof systems, potentially allowing for a higher capacity solar array. From a technical perspective, in-roof systems can offer better performance in certain conditions. The flush mounting means there’s less air circulation behind the panels, which can help them retain heat in colder weather. This can lead to improved efficiency and energy generation during the UK’s chilly winter months, which could mean more savings on your electricity bills in the long run.
Planning and coordination
Installing solar panels, especially in-roof systems, often requires coordination with other trades. For new builds or extensions, you’ll need to work closely with your builder or roofer to ensure the roof is prepared correctly for the solar installation. Timing is crucial. For in-roof systems, the solar installation needs to be integrated into the roof construction process. This means installing the panels after the roof membrane and lats are in place but before the rest of the roof tiles are fitted.
For on-roof systems, installation can usually take place at any time as long as your roof is in good condition. However, if you’re planning any roof repairs or replacements, it’s best to coordinate these with your solar installation.
How can Electrical Innovations (Derby) Ltd help?
Both in-roof and on-roof solar panel systems offer excellent ways to harness solar energy for your home. On-roof systems are more common, easier to install on existing properties and generally less expensive. In-roof systems offer a more integrated appearance and can be cost-effective for new builds or major renovations. Whichever system you choose, Electrical Innovations can help.
From solar PV panels to battery storage systems, we can recommend, design and install the best solar system for your home and circumstances to help you save money on energy and reduce your environmental impact.
To find out more and for a free, no-obligation consultation and quote, get in touch today.
