Distinguish ignition from fire spread
An electrical fault and a burning roof assembly are different stages of an incident. A poor connection can overheat; an arc can expose surrounding materials to heat. Whether and how a fire develops also depends on the specific installation and its surroundings.
VdS 3145 addresses the design and operation of PV systems with a focus on loss prevention. The FRISSBE/ZAG guideline adds important considerations for the interaction between roofs and rack-mounted modules. [1] [2]
Check connections and cables systematically
Electrical connections must comply with the approval conditions for the actual components and be made correctly. Cables need suitable routing, protection against mechanical loads and provision for weather and movement. A clear installation plan is as important as the product label.
Inspections follow the applicable requirements and the condition of the installation. A certain number of years in service does not establish a universal “safe period”. Equally, age alone does not mean that an installation is dangerous.
Glass-glass and glass-backsheet: no universal risk ranking
Modules differ in construction, rear surface, integration and testing. In an actual fire, installation, clearance, cables, connectors and roofing materials also matter. A general table declaring “module type A safe, module type B unsafe” cannot adequately describe that combination.
Building-integrated PV and rack-mounted systems also serve different building-physics and structural functions. Compare the documented modules in their actual installation conditions, rather than just the material name of their rear surface.
What a mineral protective layer can add
DEK and SHEET address the layer beneath new waterproofing; WEER addresses boards on the existing roof surface beneath PV. VLOEI represents a site-applied cement-bound layer. These approaches act on the roof assembly. They do not replace proper electrical installation.
A textile solution such as PYROFAB SOL White can be considered as another material option for the relevant protection concept. Its specific function and supporting documentation matter. Good design combines measures with complementary roles.
Inspection remains part of the concept
A passive layer cannot detect electrical faults. Electrical inspections, in turn, do not automatically change the combustibility or heat transfer of a roof assembly. Maintenance and suitable roof design therefore belong together.
Record defects, repairs and changes to modules or cable routes. Ensure that access points, isolation points and relevant roof details remain accessible in service. This keeps technical measures verifiable even after years of operation.
Treat electrical inspection and assessment of the roof build-up as separate, complementary tasks. A mineral board does not detect a faulty connector.