Commercial rooftop solar projects are built predominantly on metal racking, whether ballasted in place with concrete or mechanically attached to the roof. However, other types of materials have proven to be viable as the primary racking structure for flat-roof applications.
Some manufacturers have shifted away from extruded metals into specialty molded plastics or even incorporating concrete, which would traditionally be a ballast, into the racking itself.
Concrete solar racking from Sun Ballast.
Sun Ballast brought its proprietary concrete-racking technology to the United States in fall 2023. The company was founded in 2011 by Maurizio Iannuzzi, an Italian solar contractor, after he sought a simpler solution for the complicated flat-roof market in Italy.
“He came up with the idea to integrate ballast and racking into this single component and actually started manufacturing it for himself, so he could install it and be more efficient,” said Edoardo Brignoli, CEO of Sun Ballast USA. “In the mornings, he was manufacturing racking, and in the afternoon, he was installing them.”
The product Sun Ballast is a system of threes: it comes in three orientations (flush-mount, east-west and a 5 to 10° south-facing tilt), with three components (the concrete ballast-racking, a rubber mat to lay under and clamps to mount the modules) and in three weights (32, 64 and 96 lbs).
What makes Sun Ballast different from off-the-shelf concrete is how it’s cured. The concrete has a 5,000-psi mix, which is standard for use in weight-bearing construction projects.
“People learn the hard way that not all concrete is created equal,” Brignoli said. “It is not uncommon for us to run into jobs where installers or EPCs are having to go on a roof 10 years later, after the initial install, and basically scoop up sand, which used to be block at one point, but broke down with freeze-thaw over the years.”
The company is targeting the Northeast as a testing ground for Sun Ballast to prove it can withstand the region’s winters.
“We thought, ‘If we can figure out New England, we can pretty much figure out the rest of the country,’” he said.
Sun Ballast is cast domestically, and since concrete is non-conductive, it is awaiting approval for UL 3741 compliance — which would allow contractors to satisfy fire safety requirements without installing rapid shutdown devices on the roof.
Plastic, polymer and fiberglass racking
DynoRaxx first entered the solar mounting market in 2007 with a steel racking structure, but company reps found the assembly to be cumbersome. In 2011, it introduced a racking made from a proprietary molded fiberglass compound. DynoGrip Evolution Flat Roof System is a ballasted racking that is installed without using any tools.
DynoGrip Evolution Flat Roof System from DynoRaxx.
Fiberglass material means the racking isn’t affected by thermal expansion like its metal counterparts. DynoGrip has been installed in regions with high sun exposure, and is UV- and fire-resistant, meeting the UL 2703 rating. The racking elevates ballast blocks half an inch from the roof for air circulation and water drainage.
“In most instances, where solar was a retrofit into a building that’s been existing, they don’t really take into account placing modules and how much that affects drainage on the roof,” said Nathan Rizzo, who invented the racking. “We’re not damming or stopping the natural flow of water on the roof.”
In its 14 years on the market, DynoGrip has only undergone one change, which removed fiberglass rails and replaced them with tool-less clamps pinned to the upward supports for mounting modules.
“It speaks pretty well to the product that we initially designed and our goal with it — that it really was the evolution of solar and it didn’t require a lot of iterations,” Rizzo said.
DynoGrip racking is manufactured to be stacked on one another and palletized for simpler logistics.
FastRack, a modular rail-less racking from Sollega, uses a similar method for shipping. The first model of FastRack that launched in 2012 used a high-density polyethylene in the rail-less, modular racking before switching to glass-reinforced nylon 6 in 2014.
FastRack, a glass-reinforced nylon solar racking from Sollega.
“If you go and look under the hood of your car, you’re going to see some components that actually are made out of the same material,” said Elie Rothschild, CEO of Sollega. “The reason being is its expansion-contraction is minimal, and it has a very high heat stability.”
FastRack is composed of the primary rack, or bucket, which can house ballast blocks or mechanically attach to the roof; then there are bolts, which are placed at locations for 5, 6 or 10° panel tilts; panel clamps; and slide-on bonding jumpers. The lightweight buckets can hold up to 1,700-lb loads.
Glass-reinforced nylon has an operating lifespan of between 40 and 50 years, and it is fully recyclable. Rothschild said Sollega is considering using post-industrial recycled materials to manufacture its racking, which already has a smaller carbon footprint than extruding metals. Additionally, glass-reinforced nylon is non-conductive, so FastRack was earned UL 3741 compliance by default.
Non-traditional materials like concrete, fiberglass and glass-reinforced nylon present certain advantages for commercial solar logistically and for ease of installation by keeping component counts low. Metal remains the popular choice for flat-roof projects, but other racking options give installers alternative approaches to solar construction.
