Sandwich panels as roof coverings have their own challenges when it comes to building a photovoltaic system. These roof coverings consist of different layers that are connected to each other and usually finished with a trapezoidal sheet at the top. Roof manufacturers usually prohibit the attachment of the photovoltaic system to this top layer, as it can then come loose from the sandwich.
Complex structural situation
However, Aerocompact has developed a solution with the Comapctmetal TR, which the Berlin installation company Securenergy has now used to install a solar system on two new buildings in Nuthe-Urstromtal, Brandenburg. On an area of almost 10,000 square metres, the 4,654 modules produce a total of 1.861 megawatts.
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"The structural situation was very complex," reports Johann Egger, project manager at Securenergy. "Normally we would have used a short rail." But the risk of the top layer coming loose over time led the Berliners to resort to Aerocompact's system. "In addition, the purlin spacing was very large, up to three metres. We needed a stable solution that could also withstand high snow and wind loads," explains Egger.
Substructure stands on the purlins
Aerocompact's solution is that the mounting system is not fixed to the top layer of the sandwich panel. Rather, the mounting rail to which the solar modules are attached does not rest on the roof, but on self-drilling screws that are screwed directly into the purlins of the roof structure below.
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Because the substructure is fully supported on them, neither compressive nor tensile forces caused by wind or snow are introduced into the sandwich panels, which prevents leaks or loosening of the outer shell. Spacers guarantee that the distance between the rail and the roof can be maintained evenly.
30 per cent faster than expected
In this way, the building owner also retains the warranty on the roofing. This is because the solution is recommended by many sandwich panel manufacturers, as Albert Vonbun, product manager at Aerocompact, reports. The installation of the huge roof system in Brandenburg was very straightforward. "We were 30 per cent faster than expected," says Johann Egger from Securenergy. "That surprised us very positively." (su/mfo)
