Effective fire protection measures in the installation of rooftop PV systems
Fire... the absolute horror scenario for every building owner. Especially in cases where a rooftop PV system is installed, there are some special features to consider. Fire protection measures are an important part of planning a rooftop PV system. The risk of a fire sometimes discourages customers from having a PV system installed on the roof, but the dangers and risks involved in the installation and operation of PV systems are in fact low. According to the German Insurance Association (Gesamtverband der Deutschen Versicherungswirtschaft e.V.), only two percent of insurance damage to photovoltaic systems can be attributed to fire. After all, in principle photovoltaic systems do not differ significantly from other electrical installations.
With electrical installations the following risks must be taken into account:
- Fire caused by the electrical system
- Fire triggered by flammable cables
- Fire transmission by thermal heat conduction
However, as early as the planning stage there are possibilities of preventing fires and increasing the level of safety. Quality always has to be considered in the selection of all components. Both the PV modules and the other materials should be tested and TÜV certified. Proper installation is also crucial. For this reason our team from the Energy Systems division works exclusively with long-standing, certified partners.
Fire protection measures according to VDE "AR-N 2100-712"
Specific fire protection measures must of course be taken into account during installation. Clear guidelines for the safe installation of photovoltaic systems apply to planners and installers. In addition to electrical installation in accordance with fire protection regulations, fire protection sealing and ground and short-circuit proof cable routing, ensuring the safety of emergency services is an important factor. When planning new rooftop systems, our solar experts from the Energy Systems division work in line with the AR-N 2100-712 regulations of the VDE (Association for Electrical, Electronic & Information Technology).
Sections 4 to 7 describe organisational, structural and technical measures in more detail:
- Labelling of the PV system on the distribution cabinet as well as on the house connection box
- Display of fire brigade plans for the emergency services
- Fire-resistant laying of the DC cables outside the building
- Fireproof electrical installation, e.g. overvoltage protection
- Installation of the inverters outdoors or directly at the entrance to the building
- Use of DC circuit breakers or fireman's switches (standard) or a DC module disconnecting device (less common)
If the DC cables are laid inside the building and fire-resistant routing of the DC cables is not possible, technical measures in accordance with VDE standard AR-N 2100-712 (Section 7) are also required.
What must be observed in the event of fire: alternating current instead of direct current
If a fire breaks out despite all precautions, there is an important factor for the firefighters to consider: in contrast to the other electrical installations in buildings, photovoltaic systems produce direct current. This must first be converted into alternating current using an inverter. It is not possible to simply switch off the current here, because as long as light falls on the solar modules they generate energy, regardless of whether or not the power supply to the building has been switched off. However, the flow of current between the inverter and the switch can be interrupted by means of fireman's switches installed outside of the building. In the event of a fire, VDE also provides rules of conduct for firefighters in the form of the DIN VDE 0132 standard. Among other things, this standard specifies what extinguishing agents may be used and what the minimum distance must be when extinguishing a fire.
The regular maintenance of PV systems can in many cases prevent the occurrence of fire. The team of experts from the Service Division at SENS specialises in the optimisation, monitoring and repair of PV systems.