Structural fires aren’t new. Rapid shutdown helps first responders when solar is present, writes JD Dillon, chief marketing and customer experience officer at Tigo Energy
Building fires existed long before rooftop solar and they will continue to occur regardless of how buildings are powered.
Cooking equipment, heating systems, electrical faults, smoking materials and human error remain among the leading causes of structure fires.
The role of rapid shutdown technology is not to prevent those fires from occurring, nor was it created because solar systems are inherently dangerous. Rather, rapid shutdown exists to protect firefighters, maintenance personnel and other first responders by automatically reducing hazardous DC voltage whenever they must access a building where solar equipment is present.
The United Kingdom is experiencing its fastest period of solar growth in more than a decade. According to government data, total installed solar capacity surpassed 21 GW in 2025, with small-scale deployments reaching record levels as homeowners, businesses and public institutions increasingly turn to solar energy to reduce energy costs and improve resilience.
Across the UK, the overwhelming majority of structure fires originate from causes unrelated to solar generation. The US Department of Energy also calls fire related to solar energy “extremely rare.”
Consistently identified is cooking equipment, electrical distribution systems, smoking materials, heating equipment and accidental ignition sources as the dominant contributors to residential and commercial fires.
A Tigo Energy analysis shows that solar installations represent only a small fraction of buildings nationwide and incidents where PV equipment is involved remain exceptionally uncommon relative to overall deployment.
When a building containing solar equipment catches fire, regardless of how the fire started, the presence of energised DC conductors creates an additional operational consideration for firefighters. Traditional methods of disconnecting AC power do not eliminate DC voltage generated by sunlight, which is precisely the challenge rapid shutdown technology was developed to address.
Rapid shutdown requirements did not emerge from manufacturers alone. They were heavily influenced by firefighter organisations and first responders seeking safer access to structures equipped with rooftop PV. Fire service representatives have long emphasised that reducing voltage at the module level allows crews to operate more safely when ventilating roofs, accessing buildings or conducting overhaul operations after a fire has been brought under control.
Rapid shutdown has now become embedded within electrical codes or accepted best practices across many of the world’s largest solar markets, including the United States, Canada, Brazil and several additional jurisdictions, which is also found through an analysis by Tigo Energy.
While the UK has not yet adopted a universal rapid shutdown mandate, insurers, multinational facility owners, engineering firms and system designers increasingly recognise the technology as an important layer of electrical safety.
Why rapid shutdown has become an essential safety tool
The challenge that rapid shutdown addresses is straightforward. Even when utility power is disconnected, photovoltaic modules continue producing electricity whenever sunlight is present. During emergencies, energised conductors can pose hazards to firefighters, maintenance personnel and building operators attempting to access affected areas. This is important as perception of such incidents can harm the industry all together.
The phenomenon is not unique to solar. Autonomous vehicle accidents receive disproportionate media attention despite representing only a tiny fraction of overall
road collisions.
Likewise, when a building fire reaches rooftop solar equipment, images of burning panels often dominate headlines even when the solar installation played no role in starting the fire itself. Public perception is shaped by visibility, making proactive safety practices essential for maintaining confidence in the technology.
Rapid shutdown technology reduces this risk by quickly lowering voltage at the module
level when a shutdown event is triggered.
Products such as the Tigo TS4-A-F, TS4-A-S and TS4-A-O all provide rapid shutdown functionality, while the TS4-A-S and TS4-A-O also add module-level monitoring and optimisation capabilities that support ongoing system performance throughout the operational life of the installation.
However, rapid shutdown should not be viewed as a standalone solution. Rather, it represents one layer within a comprehensive safety framework.
This broader approach is reflected in the concept of Total Quality Solar (TQS), an adaptation of the long-established principles of Total Quality Management applied to solar deployment. Under TQS, system design, installation, commissioning, operation and maintenance are treated as a unified quality process rather than isolated activities.
Government regulations are only one driver behind rapid shutdown adoption. Fire services, insurance providers, multinational corporations, engineering firms and facility owners increasingly specify rapid shutdown because they recognise the operational value of reducing electrical hazards whenever emergency access becomes necessary. For many commercial facilities, meeting these expectations has become as important as satisfying formal electrical code requirements.
Recognising these realities, the solar industry has increasingly invested in installer education and training. Of the tens of thousands of monitored Tigo installations now deployed across the UK, more than 75% were installed in the last five years alone, accompanied by expanded technical support and hands-on training initiatives such as the Tigo Hole-in-One Tour.
By helping installers better understand monitoring technologies, MLPE deployment, commissioning best practices and rapid shutdown implementation, these programmes help reduce risk throughout the operational life of a system.
The practical value of this quality-first approach can be seen in projects around
the world.
Case study: Safety begins long before an emergency occurs
Whether driven by electrical code, insurance requirements or owner risk management objectives, projects around the world increasingly demonstrate that rapid shutdown has become an expected component of quality commercial solar design.
At Portland International Airport in Oregon, USA, a major expansion project included a 600-foot solar awning installed on a parking structure as part of broader sustainability initiatives. Because the project required compliance with National Electrical Code rapid shutdown requirements, designers selected Tigo TS4-A-F rapid shutdown devices paired with another popular global inverter brand.
Each module was equipped with rapid shutdown functionality that automatically reduces voltage to safe levels if power is interrupted or a shutdown event is triggered.
The result was a system designed not only to generate renewable energy but also to provide safer conditions for maintenance personnel and emergency responders who may need access to the structure throughout its operational life.
A second example comes from Spain, where a 371 kWp solar installation on an industrial
logistics facility became one of the country’s first commercial projects designed to meet
dedicated rapid shutdown requirements.
In this case, the driving force was not regulation but insurance. The facility’s insurer required rapid shutdown capabilities to improve emergency response readiness and reduce operational risk. The project team selected Tigo TS4-A-2F devices and RSS Transmitters to meet those requirements while maintaining design flexibility across the installation.
Both projects illustrate an important point: safety outcomes are determined long before an emergency occurs. They begin by understanding manufacturer specifications, selecting compatible equipment, implementing proper system design, thoroughly training installers and commissioning systems correctly from the outset.
Rapid shutdown technology plays a valuable role, but it is most effective when integrated
into a broader culture of quality. This mindset can be applied to installations across the UK.
Protecting solar’s future requires industry-wide commitment
Rapid shutdown addresses a very real challenge faced by firefighters whenever they respond to any building fire involving rooftop solar. As the UK continues one of the fastest periods of solar deployment in its history, maintaining public confidence will depend on more than installing additional capacity. It will require an industry-wide commitment to Total Quality Solar, where system design, equipment selection, installer education, commissioning, monitoring, optimisation and rapid shutdown work together to protect people long after installation is complete.
Building fires will continue to occur, just as they always have. By ensuring solar systems can be made electrically safe when first responders arrive, the industry demonstrates that renewable energy and public safety can continue to advance together.
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