How to install a PV system

How to install solar panels on a flat roof: Plain talk

Some solar installers scratch their heads when it comes to putting solar panels on a flat roof — not everybody is ready to take on this job. Why though? Despite seeming simple, this type of roof has a few tricks to it. Let’s break down how to install solar panels on a flat roof the right way.

Flat roof and solar panels: Benefits and drawbacks

Solar panels can be installed on any type of roof, the only difference is how straightforward or complicated the installation process is. Flat roof is right in the middle, having both advantages and challenges. In some ways, putting a PV system on top of it is a lot like building a ground installation. Let’s look at the benefits of mounting solar panels on a flat roof..

✔ More space and power

With a flat roof, you can fit more panels, because you don’t just have one working slope facing south, but the whole roof at your disposal. Also, you can use bifacial solar panels to generate even more power.

✔ More freedom and flexibility

With a standard tilted roof, sometimes it is impossible to install solar panels facing strictly south at a perfect angle. When you build a solar system on a flat roof, you can turn the panels any way you want and adjust the angle to your preference.

✔ Easier installation

If you want to mount solar panels on a flat roof without drilling, the panel mounting structures can be secured with ballast alone, say, cinder or concrete blocks. This means not only a simpler installation, but also less problems with potential roof leaks.

✔ Easier maintenance

A flat roof also offers easier maintenance: You can walk safely, rather than crawling on it. This means your solar panels will be easier to clean, inspect, and repair if necessary.

What about the disadvantages of installing solar panels on a flat roof? There are quite a few:

✖ More warranty problems

Not every company gives a warranty for panels installed on a flat roof, because they tend to pool up rainwater, which can lead to breakage. Also not every company performs flat roof installation. This means you will have to spend more time searching and choose from a limited number of options.

✖ More anchoring required

Living in a windy region, you need to take extra care when securing your solar panels. In strong winds, angled solar panels will be like sails, which means that the support structure must not only support the panels, but also securely anchor them down to ensure they are not carried away by the wind.

✖ Higher risks of leakage

Most solar panels are made to withstand winds of at least 140 mph 

Even without solar panels, flat roofs tend to collect water in certain areas. If you drill into the roof to attach the solar panels and don’t ensure a tight sealing, the water can easily get into the drill holes and make the situation even worse.

Installing solar panels on flat roof: Options

Mounting system for solar panels on a flat roof: No drilling required 

Flat roof solar panels can be mounted onto a special tub either weighed down by concrete or cinder blocks or screwed down to the roof. The panels can also be installed on metal frames, which can also either be ballasted with heavy blocks or attached directly to the roof.

Have your roof inspected before you install solar panels. If you choose to screw your panels down, provide proper sealing. Flat roofs do not have a drainage system and tend to pool rainwater. If the roof starts leaking, repairing it will be much more problematic. If you opt for concrete blocks, make sure the roof can support both the blocks and the panels, especially if your home is not a new one.

Have a different roof type or want to learn more about solar panel installation? Read our article on how to install solar panels on a roof.

Years of experience in translation and a love of nature help Julia find the right words to encourage going solar. She joined the team in 2023 and is happy to make her contribution to a greener future.

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