Abstract:
With the increasing adoption of solar power systems, photovoltaic installations are becoming a common sight in both urban and rural landscapes. In densely populated cities and consolidated villages, preventing fires in solar photovoltaic systems and curbing their spread has emerged as a critical concern. This article primarily focuses on the fire resistance testing and certification of photovoltaic module products (solar panels), including the ANSI/UL 790 fire test under the IEC 61730-2 standard, along with an introduction to Japan’s DR flying spark test.
Fire Incident on an Urban Elevated Road
On May 21, 2025, a fire unexpectedly erupted on the top of the sound barrier along Shanghai’s Hongmei South Road Elevated Road. Reports indicated that around 2:10 PM, photovoltaic panels installed on the sound barrier’s roof ignited, emitting substantial black smoke. The fire rapidly escalated, generating thick smoke and causing material debris and fragments to fall from the sound barrier’s summit, prompting passing motorists to take evasive action. Firefighters swiftly responded to the scene, bringing the blaze under control, though it left a gaping hole in the elevated sound barrier’s roof and damaged multiple photovoltaic panels. Temporary traffic control measures were implemented on the ground-level road of Hongmei South Road, northbound near the incident site, with police diverting vehicles.
On November 7, 2023, the Huadian Shanghai Hongmei South Road Elevated Sound Barrier Photovoltaic Project officially commenced construction. It was subsequently unveiled as a breakthrough in intelligent transportation development at the Sixth China International Import Expo (CIIE) Transportation Forum. This project, with a total installed capacity of 1.5MW, marked the nation’s inaugural elevated sound barrier photovoltaic installation. On April 30, 2025, the project was officially connected to the grid, garnering significant attention as a pioneering endeavor. Unexpectedly, less than a month after its grid connection, the project suffered a fire, sparking widespread discussion and concern within the industry.
While this project exemplified an exemplary application and case study for photovoltaic power generation systems, the occurrence of a fire has inevitably raised questions regarding the safety of PV systems and their susceptibility to spontaneous combustion. Although the recent incident is considered isolated, and its specific cause remains under investigation, it has nonetheless impacted the broader societal application and promotion of industry products, bringing adverse consequences to the involved companies and parties.
Fire Retardancy Testing for Photovoltaic Module Products
The application of photovoltaic modules on building rooftops is globally prevalent. To ensure product safety and usability, various authoritative third-party organizations within the industry have, through extensive evolution, established the ANSI/UL 790 fire resistance test under the IEC 61730-2 standard.
This test primarily encompasses a flame spread test and a burning brand test, both applicable to BIPV (Building Integrated Photovoltaics) and BAPV (Building Applied Photovoltaics) installations. Upon successful completion of these tests, modules are rated as Class A, B, or C. Class C represents the lowest grade, signifying compliance with minimum requirements. Rooftop photovoltaic installations should meet at least Class C or a higher grade, with additional, more stringent tests potentially required based on specific demands.
Flame Spread Test
This test primarily evaluates the spread of flames across the module’s surface and the propagation of flames between the module and the mounting roof surface. During the experiment, a gas flame is directly applied to the module, simulating real-world conditions, while the module is simultaneously exposed to airflow.
Class C:
Burner power: Approximately 325 kW
Flame exposure time: 4 minutes
Class A or B:
Burner rated power: 378 kW
Flame exposure time: 10 minutes
Burning Brand Test
Based on the requirements for Class A, B, and C, modules are mounted on a fixed support. Several burning brands, ranging in mass from 10g to 2000g depending on the class requirements, are placed and secured on the module’s surface (to prevent sliding). These brands are ignited and similarly exposed to wind.
Finally, according to the IEC 61730-2 requirements, it is assessed whether the module achieves Class A, B, or C after undergoing these two tests.
No sparks or burning components should fall from the module’s fixed support.
Flame spread should not exceed the following standards:
Class A – 1.82 m
Class B – 2.40 m
Class C – 3.90 m
Lateral flame spread must be controlled.
The above represents a selection of the testing methods and evaluations. For more detailed information, or if you require assistance with testing and certification from Pachitec, please feel free to contact us for consultation.
Photovoltaic Modules and Fire Safety in Urban Environments
In densely populated urban areas and rural settlements, fire prevention has always been a paramount concern. The high density of buildings, coupled with varied pedestrian traffic and potential ignition sources, commands significant attention. A key challenge we face is how photovoltaic (PV) modules can safely coexist within these environments.
Let’s look at Japan, a neighboring country with limited land area and a large population concentrated in urban centers. Shenzhen, China’s most densely populated city, has a population density of 8,908 people/km². Dongguan follows with 4,262 people/km², and Shanghai with 3,923 people/km². In contrast, Tokyo’s 23 wards collectively have a density of 15,510 people/km², Osaka 12,389 people/km², and Kawasaki 10,854 people/km². Notably, Tokyo’s Toshima Ward reaches approximately 23,220 people/km². These figures immediately highlight that Japanese cities have significantly higher population densities than their Chinese counterparts.
Following the Fukushima earthquake in 2011, Japan shut down its nuclear power plants and vigorously pursued new energy industries, encouraging the installation of PV systems on urban residences, factory rooftops, and even private garage roofs. However, given the high-density urban context, ensuring fire safety for PV installations becomes crucial. Below, we’ll explore Japan’s management approaches to gain valuable insights and experience.
Japan categorizes urban buildings into four primary zones:
Fire Protection Zones: These include bustling streets and areas with high building density, as well as areas along major arterial roads.
Quasi-Fire Protection Zones: Primarily located around the Fire Protection Zones.
Article 22 Zones: Encompass urban and rural areas outside the Fire Protection and Quasi-Fire Protection Zones.
Other Areas: Regions not covered by the above three zones.
Under Japan’s Urban Planning Act, Fire Protection Zones and Quasi-Fire Protection Zones are designated as specific urban and rural areas requiring fire hazard prevention. These zones have stringent fire safety standards, mandating that buildings within them must be fire-resistant or quasi-fire-resistant structures. Specifically, this means they must be reinforced concrete buildings, or steel-framed buildings with fire-resistant material coverings. Fire-resistant material covering implies that the main structural components—such as steel columns, beams, roofs, walls, and floors—must be clad in fire-resistant materials. “Article 22” refers to Article 22 of the Building Standard Law, pertaining to roof areas. Simply put, to prevent fires caused by sparks, roofs in these zones must conform to construction methods stipulated by the Minister of Land, Infrastructure, Transport and Tourism, or methods approved by the Minister. Solar installations in Fire Protection Zones, Quasi-Fire Protection Zones, and Article 22 Zones must obtain DR Fire Spread Certification. Photovoltaic buildings without this certification will be in violation of the Building Standard Law and subject to penalties and rectification. PV carports are also considered buildings and must comply with urban planning fire safety requirements. For BIPV (Building Integrated Photovoltaics), where the PV system and roof are integrated, both must simultaneously acquire fire certification. For BAPV (Building Applied Photovoltaics), the building must first obtain fire certification, after which compliant PV modules can be installed. For more information regarding DR fire certification and related requirements, please contact Pachitec for detailed assistance.
Conclusion
The coexistence of cities and photovoltaics holds the promise of a greener energy future, yet the challenges involved are equally undeniable. While the market offers a plethora of PV modules, each with its unique promotional claims—such as “three-proof” modules boasting inherent fire resistance—it’s crucial to understand that these are primarily sales rhetoric. The true measure of a module’s fire resistance lies in its fire rating from a third-party authoritative institution, such as Class A, B, or C. Paying a premium for fire performance without this certified evaluation is unwarranted. Furthermore, it’s essential for design institutes and related agencies involved in project planning to objectively assess the actual conditions of the project site. The site should be accurately categorized as a high-grade fire protection zone, a general fire protection zone, or another type of area.
We strongly advise detailed consultation before installation to mitigate potential risks and avoid property, brand, or personal losses due to fire. We also urge manufacturers, during the initial stages of product research and development, to fully consider the product’s usage scenarios and incorporate third-party fire tests into their product development schedule to enhance product reliability.
This has been a brief overview of product testing and certification for photovoltaic power generation. The PV industry in 2025 is currently navigating various challenges, including overcapacity, severe homogenization, continuously declining product prices, and corporate losses. We hope this article offers some valuable insights to the industry and anticipate a swift recovery.
