Photovoltaic systems (PV systems for short) have become an integral part of modern energy supply. They provide clean electricity and make an important contribution to the energy transition. At the same time, however, they operate continuously under voltage.
This special feature can pose a significant fire risk for photovoltaic systems in the event of technical defects. If, for example, faulty cable connections, damaged cables, or defective connectors cause so-called arcing, high temperatures develop within a very short time. This is particularly problematic in roof systems, where bundled cables are located in cable ducts and are heated up significantly by both the electrical load and solar radiation.
If a fire breaks out, it is not only the direct damage to the PV system that is relevant. For operators, consequential damage is particularly important: production or delivery failures, negative press coverage, and, last but not least, environmental damage can have significant economic consequences.
Fire hazards in PV systems
Several components of photovoltaic systems are the focus of fire safety considerations.
- DC connectors and cable connections are sensitive to installation errors and tend to arc when poorly manufactured.
- Inverters, in which currents are concentrated, can catch fire due to thermal overload or internal short circuits.
- Module junction boxes are also critical, as defective diodes or faulty solder joints can lead to overheating.
- Even DC disconnect switches—actually a safety device—can become a source of fire in the event of a malfunction.
Statistics: rare, but serious
A study by TÜV Rheinland, supplemented by Fraunhofer ISE, shows that only about one in 10,000 PV systems causes a fire with significant damage. Serious fires occur in only 0.006 percent of all systems. However, given that there are around 2.5 million systems installed in Germany, this adds up to around 150 fire incidents per year.
Fire safety requirements for PV systems
Various regulations apply in Germany to minimize the risk of fire in PV systems. DIN VDE 0100-712 describes the installation of electrical systems, while VDE-AR-E 2100-712 specifies concrete requirements for shut-off devices. DIN EN 62446 regulates tests on PV systems.
In addition, VdS 3145 for risk assessment, DIN EN 50618 for requirements for solar cables, and state building regulations with their structural fire protection requirements must be taken into account.
Responsibilities in the event of damage
Errors in installation or violations of applicable standards are the responsibility of the installer. Planning errors, such as missing disconnect switches or an unfavorable arrangement of the solar system, fall within the scope of responsibility of the planner. Operators, in turn, are liable if they neglect maintenance or prescribed inspections of photovoltaic systems.
Important: Liability in individual cases is based on the contract, duty of care, negligence, and evidence.
Fire protection measures for solar systems
A standard-compliant installation in conjunction with tested quality components forms the basis for the safe operation of PV systems. Additional safety is provided by DC load break switches in the immediate vicinity of the module field, fireproof cable bushings, and smoke and heat vents in the roof area. A clear separation between DC cables and combustible materials further reduces the risk.
Good to know: The use of modern early detection systems such as fiber optic linear heat detectors is particularly effective. This technology detects dangerous temperature rises at an early stage and enables targeted alarms to be triggered before a fire can develop.
Challenges for the fire department
Even after the power has been shut off, the DC side remains active under sunlight. Residual voltages and the risk of dangerous arcing make the operation even more difficult. Limited roof accessibility and unclear sources of fire pose further challenges.
Clear labeling of the PV system, detailed fire department plans, and easily accessible shut-off devices make the work of emergency services considerably easier.
Maintenance as the key to safety
Regular inspections are a key component of preventive fire protection for photovoltaic systems. A visual inspection once a year reveals damage such as porous cables, loose terminals, or signs of overheating. A comprehensive electrical inspection should be carried out every four years.
Important: Monitoring for shading is also highly relevant, as so-called hot spots can be caused by overloaded cells – a frequently underestimated fire hazard in photovoltaic systems.
Frequently asked questions
How high is the fire risk associated with photovoltaic systems?
The risk is statistically low. Nevertheless, the damage can be considerable in individual cases, which is why preventive measures are essential.
Which standards must be complied with?
Which components are particularly at risk?
DC connectors, inverters, module junction boxes, and DC disconnect switches require increased attention, especially in the event of installation or manufacturing errors.
How can fires in photovoltaic systems be prevented?
Professional installation, the use of tested components, regular maintenance, and modern early detection systems are crucial.
What special considerations apply to the fire department in the event of a fire?
The continuous direct current generated by solar radiation requires special caution. Clear labeling, shut-off options, and a firefighting plan support safe use.