In the Netherlands, a record number of 4.6 million photovoltaic (PV) panels were installed in the past year (2018), as reported by Dutch New Energy Research. With systems’ costs decrease, government’s incentives, and climate change awareness, the number of PV panels installed will continue to rise. However, what safety risks does this technology pose?

Electric fire hazard
Poor installation of PV panels can lead to electric fire. PV panels are normally connected to each other in series. The nature of electricity (DC) generated from the PV panel is more prone to arc faults at the connection between the panels. Arc faults trigger electric fire which can ignite combustible materials around it, this can lead to burning of PV panels and the roof. In addition, power surges from electrical appliances or lightning can lead to a spike which can trigger a fire at the electric appliance and/or the PV panel.

Roof fire hazard
The presence of PV panels on roofs has several challenges. PV panels are heavy so there is a risk of roof collapse during fire. Moreover, if there is a fire in the building, PV panels can help it spread as the underside of PV panels could be made up of combustible material (e.g. plastic). Furthermore, due to the location of the PV panels with close proximity to the roof they can help in a rapid movement of air, also known as chimney effect, that leads to the fire engulfing the roof and spread of fire from one location to another.

Some newer houses have PV panels already integrated in the roof replacing classic roof tiles. However, in this case the roof-integrated PV panels are in close vicinity to the insulating roof material and lack space for cooling. These systems are 20 times more likely to lead to fire than a traditional PV panel over the roof, as reported by Fraunhofer ISE.

Electrocution hazard
PV panels generate DC power, while buildings work off of AC power (230 V). Therefore the DC power of the PV panels should be converted to AC power before being used in the building. This generally occurs at a single point by a single inverter. As a result, the DC voltage from the panels builds up to as much as 600 volts DC. A 120 volts DC can be lethal in dry conditions. This is a major problem for firefighters who need to access the roof. Even at night, PV panels can generate electricity with the presence of artificial light.

Furthermore, if the circuit breaker is switched off, the PV panel can still generate electricity at its location. This is also known as an open-circuit voltage which is a real voltage that can lead to electrocution. The PV panel frame is also electrically energized and the presence of water can cause its electric energy to increase rapidly. Moreover, if the roof is metal, the whole roof can be electrically energized.

Preventive measures
According to Netherlands Organization for Applied Scientific Research (TNO), 27 fire incidents involving PV panels occurred in 2018. Although this is a minor number compared to the 60,600 fire incidents attended by fire departments in 2018 as reported by Statistics Netherlands (CBS), the number of PV panels is increasing and if no preventions are in place then the fire incidents in the Netherlands related to PV panels might increase.

A common cause of fire in PV panels is from poor installation and faulty panels. This can be prevented through auditing and requiring certification and training of installers of these systems.

Improvements to the PV panels and their setup can be made to make it safer. To prevent electric fire, special attention should be made to roof-integrated PV panels installation compared to traditional roof PV panels. Furthermore, the underside of PV panels should be made of non-combustible material and fire resistant construction material should be used on the roof. To protect the system from power surges, surge protectors and circuit breakers can be installed.

Firefighters should be trained to deal with fires involving PV panels. To protect firefighters from electrocution risks, the installation of micro-inverters at each connection between PV panels instead of a main inverter for the whole system can decrease the presence of high DC voltage in the system. Furthermore, optimizers can be used to reduce the open-circuit voltage to safe levels.

Building owners can help firefighters by providing signage outside the building that show that the building is equipped with PV panels. They should also provide circuit breakers that disconnect the PV panel system electricity.

Conclusion
Installing PV panels in homes and businesses is an important step towards renewable energy. Therefore ensuring proper safety is important in protecting properties and maintaining the current interest in installing these systems. Safety measures include certified installations and low risk setups through the use of surge protectors, over roof PV panels rather than roof-integrated systems, and non-combustible materials for PV panels and the roof. Furthermore, attention to the needs of firefighters must be made when installing these systems, including signage, circuit breakers, optimizers, and micro-inverters.