ᐅ Structural considerations for a balcony solar power system (BKW) on a prefabricated garage – any experiences?

Hello,

who has some experience with structural engineering and can share their insights?
I am planning to install a balcony solar power system (Quattro set from Kleines Kraftwerk) on top of my prefabricated garage.
The system consists of 4 modules (each approx. 23.8 kg (52.5 lbs)) with a tilt angle of 20°, and according to the manufacturer, each module is secured with about 80 kg (176 lbs) of ballast.

Question regarding the structural assessment including the most important key data:

Wind zone 1
Roof dimensions: 6.00 m × 2.96 m × 2.55 m (19.7 ft × 9.7 ft × 8.4 ft)
Total roof area: approximately 17.8 m² (192 ft²)
Module area (4 modules): approximately 8.0 m² (86 ft²)
Total additional load (modules + mounts + ballast): approximately 431 kg (950 lbs)
Conservative calculation (μ = 0.6): approx. 0.92 kN/m² local roof load
Extreme case (full snow load on module area, μ = 1.0): approx. 1.18 kN/m²
Reference value according to structural analysis documentation: allowable roof load 1.5 kN/m²

Are these load assumptions within the load-bearing capacity of the roof, and are there any special requirements for the point load of the ballast (protective mats will be used)?

Thanks

An aerodynamically optimized system would significantly reduce the need for ballast. Deflectors are also available as accessories for retrofitting or upgrading. The positioning on the roof also matters, as proximity to the edges greatly increases the ballast requirement. A distance of about one meter (3 feet) helps. You can distribute ballast more evenly over a larger surface area using distribution plates.

With this knowledge and these measures, you can easily avoid overloading your prefabricated garage.