Solar photovoltaic (PV) installations have rapidly become a key player in transitioning towards a low-carbon energy future. With the UK reaching 16.9GW of solar capacity in June 2024, the demand continues to grow. However, as the uptake of solar PV expands, it’s important to note the risks associated with their installation and operation—most notably, the risk of fire.
Despite common misconceptions that PV modules are the primary source of fire hazards, experts suggest otherwise. In this blog, we delve into the key fire risks associated with solar PV systems, discuss preventative measures, and explore the importance of ongoing maintenance to ensure the continued safe operation of these installations.
Dispelling Misconceptions: Fire Risks in Solar PV System
There is a widespread belief that module backsheet failure is the leading cause of fire in PV systems. However, data from the BRE Report on fire risks in solar PV systems, commissioned by the UK government in 2018 reveals a different story.
According to the report, out of 940,000 PV installations, there were only 80 reported faults. Surprisingly, PV modules represented just 5% of these faults, translating to only four reported module-related issues.
The real issue behind most fire incidents are DC (direct current) components. The report found that 59% of the recorded fire-related events in PV systems were attributed to issues with DC connections, including DC combiner boxes, isolators, and connectors.
DC Combiner Boxes: Faulty terminations or incorrect equipment selection in DC combiner boxes are among the top causes of PV system fires. These boxes collect and distribute DC power, and any component defect can lead to serious safety risks.
DC Isolators: Historically, there have been cases where AC isolators were mistakenly used in DC systems. This misuse causes the contacts to weld shut, leading to potential arcing and fire hazards.
DC Connectors (MC4): Poorly terminated or incompatible MC4 connectors can lead to loose connections, which are prone to arcing—a significant fire risk in PV systems.
This data highlights the importance of proper system design, installation, and maintenance, focusing on mitigating risks associated with DC components rather than solely emphasising PV module performance.
The Importance of Professional Installation and Design
Not all solar PV systems are created equal, and the quality of installation plays a critical role in minimising fire risks. Poor installation practices and inadequate design considerations can significantly increase the likelihood of faults and fire incidents. As well as using a reputable contractor, several key design elements should be prioritised to mitigate these risks:
- Cable Management: Proper installation of cable trays and lidding is essential to protect DC cables from damage and exposure to moisture or heat, both of which can compromise the system’s integrity.
- External Risers: DC cabling should be routed externally to reduce the fire risk within the building structure.
- Generator and Fire Alarm Interlocks: Implementing generator interlocks and integrating the PV system with the building’s fire alarm system can help isolate the system in an emergency and prevent further damage.
- Arc Fault Detection and Safe DC Disconnection: Incorporating arc fault detection within inverters and safe DC disconnection mechanisms can help prevent arcing events from escalating into fires.
When implemented correctly, these will drastically reduce the chances of fire incidents and enhance the overall safety of solar PV systems.
Preventative Measures: Designing Out Fire Risks
Preventative measures are essential to reduce the fire risk in solar PV installations. These measures should be integrated into the project’s design and installation phases to ensure long-term safety and functionality.
- External Placement of DC Components: Inverters and other DC components should be housed externally in dedicated enclosures. This provides protection from environmental factors and reduces the risk of fire spreading within the building.
- Dedicated DC Isolators at Roof Level: Installing specific DC isolators at the roof level ensures that the PV system can be safely disconnected during maintenance or emergencies.
- Fire Alarm Integration: PV systems should be interconnected with the building’s fire alarm system, allowing for early detection of faults and prompt response to potential fire risks.
- Proper Cable Tying and Protection: All cables, including MC4 connectors, should be tied up securely and protected from potential water ingress. This simple step can prevent electrical faults that may lead to fires.
Lifecycle Risk Management: The Critical Role of Operation and Maintenance
Even the most carefully designed and installed solar PV system requires ongoing attention to ensure its continued safe operation. Operation and maintenance (O&M) activities are crucial to identifying and addressing potential risks before they escalate into dangerous situations. Neglecting these tasks can have serious consequences, as demonstrated by a case of a fire involving a poorly maintained installation.
In this example, a PV module detached from the roof of a commercial building. Upon investigation, it was discovered that the mounting system had not been inspected for over a decade, leading to its deterioration and eventual failure. Regular inspections would have identified these issues early on, preventing the incident altogether.
We recommend the following O&M practices to prevent these issues:
- Annual Inspection of Mounting Systems: The integrity of the mounting system should be checked yearly to ensure that it remains secure and fit for purpose.
- DC and AC Testing: DC systems should undergo annual testing to identify potential faults, while AC systems should be inspected every five years.
- Regular Cleaning of PV Modules: Accumulation of debris, bird droppings, and pollution can affect the performance and safety of PV systems, so a cleaning regime tailored to the system’s location should be developed.
Conclusion: Prioritising Safety in Solar PV Installations
Fire safety in solar PV installations is a critical issue that requires the attention of both system designers and operators. By addressing the primary risks associated with DC components, prioritising quality installations, and adhering to a robust maintenance regime, the risk of fires in solar PV systems can be significantly reduced.
The continued success of solar PV in the UK and beyond hinges not just on the efficiency and performance of the technology but also on ensuring its safety for the long term. Through proactive design, installation, and maintenance practices, we can harness the full potential of solar energy while keeping people, property, and assets safe from the risks of fire.
By focusing on these critical preventative measures and adhering to best practices throughout the lifecycle of solar PV systems, we can ensure that solar energy continues to be a safe, reliable, and sustainable energy source for the future.
Ensure the safety and longevity of your solar PV installations by partnering with certified professionals for both installation and ongoing maintenance. Contact us today to learn more about our comprehensive solar PV services, designed to keep your system running safely and efficiently for years.
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