Installing solar panels on a level rooftop: A sound option?

Installing solar panels on a flat roof is a growing trend for homeowners looking to harness the power of renewable energy. While the process shares similarities with pitched roofs, there are some key differences to consider.

Firstly, the mounting system is critical for solar panels on a flat roof. Unlike pitched roofs, flat roofs require a system to tilt the panels towards the sun and improve efficiency. Two main types of mounting systems are used: fixed mounting systems and ballasted mounting systems.

Ballasted systems, which fix the modules by weight using heavy plates, are a common choice for flat roofs. They avoid roof damage and allow adjustable tilting, often between 6° and 20°. Penetrating systems, on the other hand, use anchors such as roof hooks or screws directly fixed into the roof structure. These provide high stability but require careful waterproofing.

Structural strengthening work may be necessary for flat roof installations to support the weight of a solar panel system. It's important to note that while the cost of solar panels on a flat roof is about 20% more than on a pitched roof due to additional materials and installation costs, the installation process is generally easier, safer, and quicker.

Solar panels used on flat roofs are identical to those used on pitched roofs. The key difference lies in their efficiency. Flat solar panels have reduced efficiency due to limited sunlight capture and increased susceptibility to water damage. Tilted panels, however, allow rainwater to drain and wash away dirt and debris, keeping them clean and in good working order.

Regular cleaning of solar panels on a flat roof is necessary due to the increased susceptibility to dirt and debris accumulation when panels are laid flat. Routine maintenance, such as cleaning solar panels, is necessary for flat roof installations to reduce the build-up of dirt and maintain efficiency.

Most installations on flat roofs won't need solar panel planning permission due to recent changes in permitted development rules. However, concerns for structural engineers involved in flat roof installations include wind uplift and increased risk of snow loads in winter.

Incorrect installation of solar panels on a flat roof can void the warranty due to potential water damage and difficulty in draining rainwater. It's crucial to ensure that the installation is carried out by a professional to avoid such issues.

Solar panels can work just as well on a flat roof as on a pitched roof, provided they are correctly angled to capture the maximum amount of sunlight. Adjustable racking systems are commonly used to achieve the best angle for the specific location. Monocrystalline solar panels are often the best choice for installing solar photovoltaic panels on flat roofs due to their high efficiency and long lifespan.

A typical residential solar panel covers about 1.5 square metres. There isn't a strict minimum size for installing solar panels on a flat roof, but available space determines the number of panels and energy production.

In conclusion, while there are challenges to consider when installing solar panels on a flat roof, the benefits of renewable energy production make it a worthwhile investment for many homeowners. It's essential to work with a professional installer to ensure a successful and efficient installation.