Dutch startup Rable has developed a self-supporting PV mounting system for fragile roofs with slopes of up to 10 degrees, reducing anchor points by 95% compared with conventional systems. The galvanized-steel structure distributes loads of 6 kg/m² to 15 kg/m² and can reduce installation costs by €0.15 ($0.16)/W, according to the company.
Dutch startup Rable has developed a PV mounting system designed to enable solar installations on fragile roofs with limited load-bearing capacity. Called Rable4Roofs, the system uses a self-supporting structure to distribute loads more evenly and significantly reduce the number of anchor points required.
The mounting structure is made from galvanized steel sourced from Belgium and comes with a 15-year corrosion warranty. Its lattice design is central to the system.
“It is a self-supporting, cost-effective solution for fragile roofs, roofs with Class B insulation and parking structures, particularly for east-west configurations,” Mevanly Karamoko, a sales engineer at Rable, told pv magazine. “It also requires 95% fewer anchor points than conventional mounting systems, which represents a major advance for the market.”
It can be installed on flat or slightly pitched roofs with slopes of up to 10 degrees without compromising waterproofing. According to Rable, the system can also eliminate the need for roof renovations, which can cost up to €125/m², depending on the building.
Load distribution
The system’s stability relies on a structural design combining compression elements in the supporting framework with tension elements provided by cables. Together, these components form a rigid lattice that distributes loads and withstands environmental forces, including wind and snow.
“The system’s weight is supported by the roof purlins rather than the roof panels themselves,” Karamoko said. “This allows us to achieve loads of between 6 kg/m² and 15 kg/m², compared with two to three times that amount for conventional mounting systems, which can be problematic for fragile roofs.”
The PV modules are installed on dedicated rails designed to ensure alignment, mechanical stability and natural ventilation while allowing rainwater to drain freely. Depending on site requirements, the system can incorporate individual anchor points, typically at its ends, at a rate of approximately one anchor point per 25 modules.
Loads from the mounting structure are transferred to the roof through rubber-granulate pads. The pressure exerted on the roof surface depends on its allowable load-bearing capacity, starting at 3 kPa. Rable offers different pad configurations to accommodate varying structural requirements.
275 modules installed in 2.5 hours
The system is delivered to the installation site preassembled, reducing on-site assembly time.
“The structure simply needs to be unfolded, positioned, secured and screwed into place,” Karamoko said. “Two installers can install the mounting structure for 275 solar panels in just two and a half hours.”
In its first 30 months of operation, Rable has purportedly completed 60 PV projects, ranging from 50 to 5,000 modules per installation.
The company is also involved in two projects in France, including a 260 kW rooftop installation at a supermarket in Châtenoy-en-Bresse, in the Saône-et-Loire department.
“The roof was particularly fragile, with very limited load-bearing capacity. Another challenge was the relatively soft insulation, classified in France as Class B compressibility insulation,” Karamoko said. “Insurers generally refuse to cover installations on this type of insulation, but our mounting system makes it possible to overcome this constraint.”
According to Rable, the project achieved a structural load of 13.7 kg/m² and reduced capital expenditure by €0.15 ($0.16)/W.
Karamoko said the company expects to complete its first 10 installations in France by December. He identified France’s Décret tertiaire, which sets energy consumption reduction targets for tertiary-sector buildings, as a potential driver of demand for the company’s mounting technology in the coming years.
The patented system has an ETN (Enquête de Technique Nouvelle), a French technical assessment used to evaluate the suitability of innovative construction products and installation methods for specific applications, valid until 2028. The assessment provides technical documentation that can support acceptance of the system by insurers and construction stakeholders, subject to its scope and conditions.
Rable is also pursuing an ATEx (Appréciation Technique d’Expérimentation), a technical appraisal issued by France’s Scientific and Technical Centre for Building (CSTB) to assess the feasibility and risks of innovative construction solutions before they obtain more established technical approvals
Founded two and a half years ago, Rable is currently expanding its presence across European markets.
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