Most buildings you see with solar panels have sloped roofing. But in climates where there is not much show, flat roofing is more common. This leaves many wondering if solar panels can be installed on flat roofing. The answer is yes. The first thing to point out is that flat roofing is not entirely flat. There is always a slight pitch to promote proper drainage and prevent pooling. If the slope of a roof is 16.7% or less, it is considered flat. Pitch is always directed towards the gutters and will keep water from pooling around the solar panels.

Solar Panels on a Flat roof: What Do You Need To Know?

There are two types of solar panel systems that can be used for flat roofing. One is attached using bolts or screws and the other is ballasted. There are pros and cons to each system and you should consult with a professional installer to decide which is best for your roof and building. You should always discuss the equipment that is being chosen for your home solar system, and understand why it is being used.

Attached Solar Racking Systems

The attached racking system is similar to the system used for sloped roofing. These systems are held in place by fasteners of some sort. Mounts are secured to the roof deck so it involves drilling into the roofing materials so the fasteners can be attached to the underneath surface. The system is attached to the sheathing making it very secure, so your panels will not blow away in high winds. Because holes are drilled into the roofing, it is important to make sure these are made waterproof to prevent leaks and damage.

Ballasted Racking Systems

Ballasted systems use weights such as concrete blocks to keep the panels in place. In some cases, a few fasteners may be needed but for very low-sloped roofing, this is not necessary. In areas of high winds or earthquakes, the fasteners will be recommended in addition to the ballast. Except when fasteners are used, ballasted systems do not require you to drill into the roofing, so there are few holes if any. The risks of leaking are significantly smaller. Unfortunately, ballasted systems weigh more so your roofing and building structure need to be able to support the extra weight.

Tilt or No Tilt?

Solar panel racks can be tilted to capture the most amount of daily sunlight. Systems designed for flat roofing typically have a small tile but not enough to create ideal exposure. To solve this, you can get tiltable racking systems with both attachable and ballasted mounting. This way, you can tilt your panels to sit at ideal angles for catching the most sun all year round. One important factor to remember is that tilted systems do not allow you to place multiple rows of panels close together. If you have limited roofing space, this may not be an option.


There are options when it comes to putting solar panels on flat roofing, so reach out to us today and we can help you decide which is the best system for your property.


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