Solar Panels on Flat Roofs: Costs, Pros & Cons (July 2025)

Yes, you can install solar panels on flat roofs. For these panels, it's important to leave sufficient spacing between the solar panel rows for access and to prevent shading from one row onto the next. While a flat angle may not be ideal for optimal energy generation, they can angled properly with the right equipment.

Solar panels can even be easier to maintain on a flat roof than on angled roofs. However, to maximize efficiency, you'll need a mounting system to tilt the panels towards the sun at the correct angle. They can also take up more space, requiring area for proper ventilation and preventing panels from shading each other. You can even install in roof solar panels on your flat roof.

It's important to remember that flat roofs can have disadvantages, such as minimal slope allowance, if you do not use an adjustable ballast or stand. They will also require more space per kW since solar panels on stands and ballasts need to be spaced out, as mentioned earlier.

With flat roofs, the installer has to set the pitch of the solar panels (typically between 30° to 50°, while the best orientation for solar panels in the UK is southward). This can be beneficial as it allows for optimal angling and positioning for your region. Another advantage of a solar panel installation on a flat roof is that the direction the roof faces plays a lesser role since there is more freedom to angle and position it.

Aside from flat roofs, you can also have low-sloped roofs and pitched roofs. Each of these has its advantages and disadvantages.

Low-sloped roofs are common in the UK and can be used to install solar panels, although they may not always have the ideal angle for efficiency. A low slope is generally one where the pitch is between 4:12 and 2:12.

Low-sloped roofs require less roofing material per square foot making them easier and safer installation and repair processes. They can also offer better drainage than flat roofs. On the other hand, much like flat roofs, they can be more susceptible to issues with heavy snow. As a result, this could be hazardous to solar panel fixtures and less likely to clean on its own.

Pitched roofs still exist in the UK and have some pros and cons when it comes to installing solar panels. The slope angle brings about better run-off for debris, water, and snow making it easier for solar panels to stay clean on their own. There is a lower probability of water buildup, which can lead to leaks and mould damage.

However, the installation process, maintenance, and repair are more challenging due to the slope. Pitched roofs can also be less safe to install on and more expensive.

For different slopes/angles, here are the levels of sunlight capture for solar panels in the UK:

Note: 100% refers to the ideal amount that the panel can capture, and does not refer to efficiency.

Luckily, with adjustable ballasts, you can angle the panels however you want. This can also be great for adjusting them across the seasons as the sun changes position.

For an average 2 to 3-bedroom house, flat roof solar panels cost between £2,800 and £12,100 on average when taking into account system costs and the cost of ballasts. The average home in the UK is usually a 2 or 3-bedroom house, which means that they can cover their electricity needs with a 3kW to 4kW system.

The prices above assume 400W to 450W panels per ballast.

Installing flat roof solar panels in the UK can potentially be less expensive as the process is usually easier, even with the added costs. This can depend on the number of panels and what type of mounting system. All in all, flat roofs provide stable footing for any installer and, with ballasts or other types of mounting systems, they can be quicker and thus require fewer man-hours.

The best solar panels for your home don’t necessarily have to be the most costly. They should primarily meet your home energy needs and fit your available roof space. If you have abundant roof space, you can opt for more low-power, low-cost panels and get a lower rate for the same overall system output.

Keep in mind that the costs above do not include additional components like solar battery storage systems (which we recommend). Similarly, these numbers are best adjusted for domestic use. For offices or other high-power buildings, you may want to consider commercial solar panels. You can also use our solar calculator to estimate potential solar panel costs, savings and payback time based on your home address.

The average 2 to 3-bedroom house can save between £485 and £1,110 annually by installing solar panels. This is true of flat roofs and well as sloped roofs so there is no real difference between the savings of the two setups. The average home can expect to break even in 6 to 11 and can potentially save on labour costs, keeping their expenses on the lower end of the average price.

Flat roof solar panels can be cheaper to install but this often depends on the person you hire. That’s why getting a reliable installer is the best way to keep costs down. While this can often take days of monotonous research, we can do the legwork for you with our network of thoroughly vetted installers.

Our service can provide you with up to 4 free, non-binding quotes and all you have to do is fill out a 30-second form. Click the button below to get started.

Pros:

Cons:

If you’re still wondering “Are solar panels worth it?”, you should consult a professional installer to determine whether your home is suitable for solar installation. Finding a reliable one can take an exhausting amount of time (often days of research), which is why our service can be a better alternative. With a simple 30-second form we can provide you with up to 4 free, non-binding quotes.

We’ve vetted all the installers in our network so you don’t have to go through the trouble of seeking out companies and comparing their rates. Click the button below to get started.