Photovoltaics and Fire Protection: How Operators Can Reduce the Fire Risk of Their PV System

VdS 6023 outlines structural, technical, and organizational measures that contribute to risk minimization – and what operators, installers, planners, and insurers should pay particular attention to.

Photovoltaic systems are an integral part of our energy supply. They operate reliably and safely in everyday use. Nevertheless, the same principle applies to them as to any other electrical system: product defects, errors in planning or installation, aging, external influences, or neglected maintenance can all cause a fire hazard.

On a roof, it's not just the PV technology itself that's critical. Many roof structures contain flammable insulation materials, sealants, or other building materials. If an electrical defect occurs, the PV system can become an ignition source and influence fire spread. Additionally, flammable components of modules, cables, wires, and fasteners contribute to the fire load.

The publication VdS 6023:2026-05 therefore describes ways to reduce the fire risk of photovoltaic systems on roofs. Its focus is particularly on industrial, commercial, and municipal buildings. However, the basic principles are also relevant for other rooftop installations: risks must be considered on an object-specific basis, and appropriate measures must be planned early, implemented professionally, and maintained permanently during operation.

At a glance: five principles for safe operation

• Assess the system and roof together - not just individual components.
• Ensure planning and acceptance by qualified specialists.
• Pay particular attention to DC cables, connectors, and inverters.
• Mandatorily organize inspections, visual checks, thermography, and monitoring.
• Have the entire system inspected after a fire, hail, or technical defect.

Where do fire risks arise in photovoltaic systems?

Fire incidents rarely have a single cause. In practice, several factors often converge: an electrical fault, an unfavorable roof structure, insufficient clearances, or a weak point that was not detected during inspections and maintenance.

VdS cites, among other things, defective products, errors in planning and installation, aging, external influences, and improper use as possible causes. Neglected maintenance can further exacerbate these risks.

Typical technical weaknesses from practice

Connectors: Improperly installed, damaged, or incompatible connectors can cause increased contact resistance, leading to localized heating. In the worst case, a DC arc fault can form.

DC cables: Cables must not lie unprotected on the roof surface or rub continuously against sharp edges. UV radiation, movement, water, ice, animal bites, and mechanical stress can impair insulation.

Arc faults: DC arc faults can generate high temperatures and persist for extended periods. Inverters with activated arc fault detection and shutdown can provide additional protection.

Modules and Hotspots: Microcracks, cell damage, defective bypass diodes, or other faults can lead to localized heating. Thermographic inspections help identify conspicuous areas.

Inverters: Inverters are components subjected to high thermal and electrical stress. Faults, contamination, unsuitable mounting locations, or impaired cooling can contribute to malfunctions and, in individual cases, fire risks.

External influences: Storms, hail, lightning strikes, snow, falling objects, or animal bites can cause damage that is not always immediately visible externally.

Why the roof structure plays a central role

The fire risk of a rooftop system cannot be assessed solely based on the modules or inverters. The interaction of the PV system, roof waterproofing, thermal insulation, roof structure, penetrations, firewalls, and existing protection systems is crucial.

Flat or low-slope roofs often consist of several functional layers. These can have very different fire properties. In particular, flammable sealants and insulation materials can ignite in the event of a defect and promote independent fire spread. Metal sandwich elements must also be evaluated differently depending on their construction and insulation core.

Furthermore, rooftop PV systems are often located outside the immediate protection and monitoring area of existing fire alarm or extinguishing systems. A fire can therefore develop on the roof before it is detected or combated by the building's technical systems.

For operators, this means: documentation of the roof structure is an essential part of the risk assessment. If materials or layers are unknown, they should be professionally clarified before a new installation, expansion, roof renovation, or repowering.

Planning and Installation: Reducing Risks Early

For new installations, many protective measures can be relatively easily considered during the concept and planning phase. For existing systems, structural adjustments are often more complex. However, roof renovations, inverter replacements, or repowering offer good opportunities to re-evaluate existing risks and reduce them specifically.

VdS recommends involving the insurer already in the concept phase. This allows object-specific requirements to be incorporated into the planning early on. Furthermore, a review of the planning and acceptance before commissioning by a qualified PV expert can be useful.

What to pay particular attention to during execution

· Securely fasten DC cables and protect them from mechanical stress.

· Avoid unnecessary additional connectors and use only system-compatible components.

· If necessary, route cables uncut in raised cable tray systems made of perforated metal.

· Avoid penetrations and openings or seal them professionally.

· Maintain sufficient clearances from firewalls, skylights, and smoke and heat exhaust systems.

· Fully restore the function of an existing lightning protection system after the work.

· Consistently observe manufacturer specifications regarding mounting location, clearances, ventilation, and operating limits.

· Plan maintenance and rescue routes from the outset.

Structural, technical, and organizational measures

Which measures are necessary or sensible can only be decided on an object-specific basis. VdS distinguishes between structural, technical, and organizational options. In many cases, a combination of several measures is effective.

These examples are not a universal checklist for every object. The selection and combination must match the system, the roof, the building's use, and the insurer's protection goal.

Maintenance is active fire protection

A properly planned and installed system remains permanently safe only if its condition is regularly checked. Weather, temperature changes, aging, and mechanical influences act on modules, cables, connectors, substructures, and inverters for decades.

VdS lists organizational measures including regular inspections and maintenance work, a metrological inspection at least every four years, semi-annual visual inspections, and additional inspections after special events such as storms. Furthermore, annual thermography, the forwarding of fault messages, and monitoring of essential operating data are mentioned.

The specific inspection and maintenance intervals should be determined on an object-specific basis. If anomalies are detected and repairs cannot be carried out immediately, shorter inspection intervals are necessary. It is crucial that messages are not only recorded but also evaluated and trigger clearly defined measures.

Documentation creates transparency and security

Complete and up-to-date system documentation supports safe operation. It facilitates inspections, repairs, and the procurement of suitable spare parts. In the event of damage, it also helps experts and insurers understand the system's condition, changes made, and implemented protective measures.

Documentation should particularly include:

• Layout, string, and wiring diagrams
• Datasheets and manufacturer documents
• Commissioning, measurement, and test protocols
• Maintenance and inspection records
• Thermography reports and documented anomalies
• Proof of repairs, modifications, or component replacements
• Description of the roof structure and implemented risk reduction measures

Appendix B of VdS 6023 contains a form for risk minimization. Operators, planners, and installers can document structural, technical, and organizational measures in it. Together with a detailed description of the roof structure, this form can support the insurer's risk assessment.

After Fire, Hail, or Technical Defect: Inspect the Entire System

If a photovoltaic system is repaired after a fire, hail damage, or a technical defect, not only the obviously damaged components should be replaced. Take the opportunity to have the entire system checked. Often, further weak points can be identified that could later lead to yield losses or safety risks.

Such weak points can include aged connectors, damaged cables, microcracks, thermally conspicuous modules, insulation faults, or worn components. A holistic inspection helps to avoid consequential damage and renewed failures.

Operators can find suitable replacement modules, inverters, and other PV components on the SecondSol marketplace or through SecondSol Spare Parts Management. Especially for older systems, procuring compatible components is often challenging. A targeted spare parts strategy can help to continue operating the system economically and avoid unnecessary complete replacements.

Why the topic is relevant for insurers

For insurers, the focus is not just on the PV system as a single technical system. The overall risk from the building, roof structure, use, PV technology, protective measures, maintenance organization, and documentation is crucial.

A professionally executed roof construction can meet building code requirements and still require additional measures from the perspective of asset protection as soon as a PV system is installed. Therefore, an object-specific risk assessment and early coordination between the operator, planner, installer, and insurer are advisable.

The more transparently the roof structure, technical execution, inspections, and protective measures are documented, the more soundly the risk can be assessed. VdS 6023 serves as a guide; it is non-binding, and insurers may accept other requirements or solutions in individual cases.

Checklist for Operators

Conclusion: Safety is created throughout the entire lifecycle

Photovoltaic systems are established and fundamentally safe electrical installations. However, on roofs with flammable building materials, a technical defect can become an ignition source and influence fire spread. Therefore, PV technology and the roof must not be considered separately.

The most effective risk minimization begins in the planning phase, continues with high-quality installation, and remains an organizational task throughout the entire operation. Regular inspections, visual checks, thermography, monitoring, and complete documentation help to identify weak points early.

Especially after fire, hail, storm, or technical defects, a holistic system inspection is worthwhile. Those without a fixed service partner can find suitable specialist companies and experts via the SecondSol Business Directory. Needed replacement modules, inverters, and other components are available via the SecondSol marketplace and spare parts management.

Frequently Asked Questions about Fire Risk in Photovoltaic Systems

Does a photovoltaic system increase the fire risk of a building?

A PV system is an electrical installation and can become an ignition source in case of a fault. On roofs with flammable building materials, additional fire loads and potential fire spread paths are added. The level of risk depends on the specific roof structure, technical design, and maintenance.

Do fires mainly originate from solar modules?

Not necessarily. Relevant weak points include connectors, DC cables, inverters, arc faults, and installation errors. Aging and external influences can also play a role.

How often should a PV system be inspected?

VdS mentions, among other things, regular maintenance measures, a metrological inspection at least every four years, semi-annual visual inspections, inspections after special events, and annual thermography. The specific intervals must be determined on an object-specific basis.

What should be done after hail or storm damage?

Even without immediately visible damage, the system should be professionally inspected. Microcracks, damaged cables, or loosened fastenings can initially remain inconspicuous. If anomalies are found, a more extensive technical inspection is required.

What role does the inverter play in fire protection?

A professionally selected and installed inverter is central to safe operation. Devices with activated arc fault detection and shutdown can provide additional protection. Cooling, mounting location, fault messages, and maintenance are also important.

Where can operators find a specialist company for a system inspection?

In the SecondSol Business Directory, operators can search for installation companies, experts, and service providers who offer maintenance, safety inspections, repairs, or technical evaluations.

Where can replacement modules and inverters be procured?

Operators can find suitable replacement modules, inverters, and other PV components on the SecondSol marketplace. For hard-to-find components, SecondSol Spare Parts Management also provides support.