What Is a Flat Roof Solar Ballast System?

MRac Flat Roof Solar Ballast System

A ballasted system is a type of flat roof racking system typically used on flat or low-sloping roofs. A ballast system uses a calculated ballast (weight) to secure the solar panels and mounting kit to the roof, this is an industry standard for flat roofs and is used globally. The ballasted roof system is extremely cost effective for large, open rooftops due to its quick and easy installation. Next, we'll explain what a flat roof solar ballast system is and what you need to know about it.

What Is a Flat Roof Solar Ballast System?

A roof solar ballast system is a method of mounting solar panels on a flat roof. Concrete blocks are placed in a ballasted racking system to weigh down the solar array and protect the panels from weather elements such as wind and snow.

This aluminum racking system is common in larger commercial projects where the property owner wants to make as few penetrations as possible while adding solar to their property. Flat roofs are ideal for solar installation because system assembly and access to the roof are often very quick.

How are Ballast Mounted Solar Systems Installed?

Whereas most other roof mounts are secured to the building's roof beams via roof penetrations, ballast mounts are secured with weight.

A solar racking system is connected to the solar panels. Trays beneath the panels of that racking system will hold heavy concrete blocks. The weight of these blocks keeps solar panels on flat roofs in place.

While the system will be installed on a flat roof, the solar panels will most likely be installed at an angle. Installing solar panels at an angle allows them to receive more sunlight, allowing them to produce more electricity. Furthermore, a slight angle can help snow and rain slide off instead of accumulating on the face of the panel.

Advantages of Flat Roof Solar Ballast Systems

The weight of rocks or concrete blocks is used in ballasted systems to resist wind uplift and seismic shaking forces acting on the solar array. Ballasted systems typically consist of a grid of interconnected rows and columns capable of (partially) transferring point loads from one module to multiple neighboring parts of the system. Because the forces can be averaged over a larger area, this reduces the required ballast weight in individual parts of the array. As a result, the weight of ballasted systems is best optimized in large PV arrays with high load transference.

The primary advantage of ballasted solar arrays is that they can be installed without requiring roof penetrations. Instead of requiring a roofing contractor to seal penetrations, this allows the installation process to rely on simple mechanical assembly. Indeed, some ballasted products are ready to assemble as soon as they are unpacked from pallets, resulting in remarkably short project timelines.

The Mibet flat roof mounting system is available in two configurations: horizontal south and east-west. It's aerodynamic and has been ballasted optimized through additional wind tunnel testing. Please visit this page to learn more.

A Few Things To Consider

Mibet China Flat Roof Ballast System Project

The Roof Must Support the Added Weight

Ballast mount systems are held in place by weight, so your roof and building must be able to withstand this additional load.

The average 60-cell solar panel weighs around 40 pounds, which isn't a problem for most commercial roofs in good condition.

Regardless of the type of roof-mounted system you install, the drawings must be approved by a third-party structural engineer before installation can begin.

Strong Winds Necessitate Even More Weight

Ballast mount systems are built to withstand strong winds. The stronger the winds in your area, however, the more weight will be required to keep your solar system in place.

High-rises, for example, may be at risk because of the high winds they experience. Or structures on or near the coast. If this describes your building, your ballast mount may require additional weight to keep those panels secure. That entails a sturdy roof with sturdy supports.

The Roof's Condition Is Important

As with any other roof-mounted solar system, you should ensure that your roof is in good condition. Panels should only be installed on a roof that is in its early stages of life and in good enough condition to support panels for several decades.

We usually discourage people from installing solar panels on a roof that has a shorter remaining lifespan than the solar panels' payback period. For example, if your solar system has a 10-year payback, don't install the panels on a roof that only has 7 years of useful life left. The cost of removing and reinstalling your panels is something you'll want to avoid if at all possible.

What Is the Flatness of Your Flat Roof?

Most flat roofs are not completely flat, and this is on purpose. They can have a small pitch of less than ten degrees, which aids in water drainage.

A ballast mount should work well on your building if your roof is three degrees or lower in pitch. However, if it is much steeper than this, additional weights will be required to keep your system secure, which may exceed the weighted capacity of your roof.

Final Words

A structural engineer must confirm that the additional weight and wind load can be accommodated in the design before installing a ballasted PV system. The ballast itself can come in a variety of shapes and sizes, and it is critical to ensure that the static load generated by the designed ballast is appropriate and sufficient in accordance with the wind load calculation report.

A suitable protection layer must be allowed for in all ballasted applications. It is also critical to ensure that the installation of a ballasted PV array does not void any roof warranties. This must be agreed upon with the supplier of the waterproofing warranty.

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