Fire safety of photovoltaic system

Fires in photovoltaic systems are rare. The small scale is best demonstrated by data from the German Fraunhofer ISE institute. In 20 years, only 350 PV fires have been reported in Germany. This is 0.006% of the 1.4 million solar power plants in our neighbouring country. This is largely due to the fire safety measures that are in place for all photovoltaic systems. Fire safety of photovoltaic system – what fire regulations apply to photovoltaics in Poland?

Fires in photovoltaic systems are primarily caused by atmospheric factors. Dangerous situations usually occur during thunderstorms or gales, and especially as a direct result of lightning strikes. External factors, unrelated to photovoltaics itself, account for more than half of the cases. It should be remembered, however, that the cause of a fire can also be due to improper construction of the photovoltaic system or the use of low-quality components. This is particularly the case with incompatible MC4 connectors, where electrical arcing can occur.

The fire regulations for photovoltaics, amended on 19 August 2020, have increased restrictions so that there is less risk of incorrect installation. What is worth knowing about the fire safety of a photovoltaic system?

Fire safety design principles for photovoltaic systems

The design of a photovoltaic system should not only take into account the high yield, but also the safety of using your own solar power plant. The preparation of the documentation should include detailed data on the fire resistance of individual plant components. Fire prevention recommendations, supported by standards (e.g. the German VDE-2100-712 standard), concern both the quality of the components and the PV system itself. For this reason, it is good practice to entrust the investment to an experienced installer with appropriate tools and safeguards. In this way you can avoid common mistakes, such as incorrect cable routing on the DC side, inadequate grounding of the installation, wrong crimping of the MC4 connectors on the wires or insufficient sealing of the connectors with rubber o-rings.

However, the rules concerning the design of PV systems in terms of fire safety are not precise, so a lot depends on the meticulousness of installation companies. In a well-made installation, high-quality materials are used which are covered by appropriate approvals. This applies not only to the photovoltaic panels or inverter themselves, but also MC4 connectors, surge protections, hooks or even cable hangers. These should be routed without tension, away from hot and sharp elements, preferably in conduits to protect against shock.

A frequently recommended solution to increase fire safety is the use of power optimisers. A similar role can be played by microinverters serving individual PV modules or groups of panels. The panels themselves should be cooled, which is achieved by mounting them at a distance of at least 10 cm from roof surfaces covered with combustible material. Also, do not forget arc flash devices (AFCI), arc flash detectors (AFD) or interruption devices (ID). It is important to have an easily accessible, well-marked main switch that can be used in case automatic safety systems fail.

Photovoltaic system and fire safety approval

The regulations updated on 19 August 2020 have clearly sorted out the fire safety guidelines. Previous standards based on Article 6b of the Act of 24 August 1991 on fire protection did not take into account the characteristics of a domestic photovoltaic system. According to the new regulations, any installation with a power greater than 6.5 kWp requires that the project be agreed with a fire protection expert and that the authorities of the State Fire Service be notified.

The first stage of the agreement is to discuss the needs and make a preliminary design. The project may include electrical measurements, thermal imaging or fire safety analysis of the building. It is crucial to indicate the characteristics of fire risk, technical solutions used to reduce the risk of fire, as well as guidelines on how to facilitate the firefighting action. The project must also include information about fire protection of the components, the way of marking the area and fire-fighting equipment located in the building. A correctly executed project is then reviewed by a fire expert.

Notification of the photovoltaic system to the fire brigade

Once the photovoltaic micro-system has been installed, the completion of the investment must be reported to the authorities of the State Fire Service. Fortunately, the procedure is not difficult and it is enough to use one of the available templates. The whole document fits on one page and contains information such as: the power of the system; the height, volume and area of the building; the number of floors; as well as the fire qualification and fire load density.

The application must state whether there is an explosion hazard and the anticipated number of people in the building. The notice of completion of the photovoltaic system must be accompanied by a photocopy of a design agreed with a fire expert. It is best to submit the documents in person at the district or municipal headquarters of the SFS (competent for the location of the building), where you can obtain a confirmation of receipt. The notice should be submitted in two identical copies.

Photovoltaic fire switch – Projoy

One of the most important safety features of any photovoltaic system is the fire circuit breaker. It insulates the DC cables between the photovoltaic panels and the inverter. The Projoy automatic fire switch shuts down and isolates the system in the event of a fire (the device has its own temperature sensor) and when the power is disconnected during a rescue operation. This makes operation much safer. The fire switch is mounted right next to the panels to reduce the length of high-voltage cabling. In the case of Projoy switches, the built-in DC isolator triggers automatically at 70°C.

Want to know more about designing photovoltaic systems? Read what types of installation there are for photovoltaic panels.

Check the offer of photovoltaic fire switch – Projoy.
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