Did you know – 97% of all PV arrays have safety concerns; does your fire risk assessment recognise these?

Ninety-seven percent of rooftop PV systems show safety defects linked to ignition risk.  That single statistic should stop every property manager and building owner in their tracks.

Photovoltaic arrays are now embedded across the UK’s built environment, often installed with the best of intentions: to reduce carbon, cut energy costs, and meet ESG targets. Yet the uncomfortable reality is that PV systems introduce live electrical infrastructure onto roofs that were never designed to accommodate them—and they continue to generate energy even when the rest of the building is shut down.

Government-commissioned research and international fire data confirms that PV-related fires are not rare anomalies. They occur repeatedly, throughout the operational life of systems, and most often originate from components that degrade silently over time. The majority of defects are not obvious, not visible from the ground, and not captured by traditional fire risk assessments.

For many buildings, the question is no longer if PV arrays affect fire risk, but whether existing fire strategies, assessments, and maintenance regimes still reflect how the building actually performs in a fire today.

Research Findings

It is estimated that over 160,000 commercial and residential blocks have PV arrays on their roofs.  International analysis across five countries identifies an average of 29.3 fires per gigawatt of installed PV capacity every year. Even allowing for under- or over-reporting, this confirms that PV fires occur routinely throughout the operational life of systems. Where causes are known, DC isolators, inverters, and electrical connectors are the most common ignition sources—components known to degrade, loosen, or fail if poorly installed or inadequately maintained.

The most striking finding is from over 600 rooftop PV safety audits, 97% of systems exhibited ignition-related safety defects. This indicates that, without periodic review, the likelihood of a fire-relevant defect emerging over time is exceptionally high.

For property managers, the implication is clear: fire risk assessments, fire strategies and maintenance programmes that do not actively consider ageing PV systems are out of date.

Whole Building / Interoperable Approach

The presence of photovoltaic (PV) arrays fundamentally alters how a building behaves in fire. Treating them as a stand-alone asset or a simple bolt-on technology is a critical mistake. For property managers and owners, PV systems must be addressed through a whole-building, interoperable approach that connects fire risk assessment, fire strategy, and maintenance into a single, coherent risk management framework.

As PV arrays introduce additional ignition sources, these risks do not sit neatly within one discipline. They interact directly with roof construction, compartmentation, detection and alarm systems, smoke ventilation, firefighting access, and emergency procedures. If these interactions are not actively reviewed, existing controls may no longer perform as intended.

Fire risk assessments should therefore be formally reviewed and updated to explicitly consider PV-related ignition mechanisms, concealed fire spread beneath panels, and the implications for firefighter safety and access. Assumptions made prior to PV installation may no longer be valid and must be tested.

Fire strategies must also evolve. Isolation arrangements, roof-level compartmentation, and the effectiveness of detection, suppression, and ventilation systems all require reassessment where PV arrays are present. Any departure from original design intent should be clearly identified, justified, and recorded.

Equally, maintenance regimes are critical. Evidence consistently shows that poor installation, component degradation, and inadequate inspection are dominant contributors to PV-related fires. Inspection and maintenance plans must be updated to include targeted PV checks by competent persons.

For Higher-Risk Buildings, these issues must be fully embedded within the safety case, demonstrating that PV risks are identified, controlled, and managed throughout the building lifecycle. In short, PV arrays demand integrated thinking—anything less leaves material fire risk unmanaged.

Conclusions – the call to action

PV arrays are not a “minor roof issue”. They fundamentally change ignition risk, fire spread potential, firefighter safety, and the reliability of existing fire protection measures. Continuing to rely on fire risk assessments, strategies, and maintenance plans written before PV installation is a clear governance failure.

Property managers and owners must act now:

• Review fire risk assessments to explicitly address PV ignition sources, roof-level fire spread, and emergency response implications.

• Revalidate fire strategies against the altered risk profile introduced by PV systems, documenting any deviations from original design assumptions.

• Update maintenance regimes to include competent, routine inspection of PV components and cabling.

• Integrate PV risk into safety cases for Higher-Risk Buildings, demonstrating ongoing control and management.

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PV-related fire risk is foreseeable, measurable, and manageable—but only if it is recognised. Doing nothing is no longer a neutral position; it is an active acceptance of unmanaged risk.

Author David J. Hills FRICS, FIIRSM, MIFireE, MSFPE, RSP
Senior Director - Regulatory, Technical & Technology Solutions