How Are PV Modules Tested for Fire Resistance?
Photovoltaic (PV) modules, also known as solar panels, are the heart of solar energy systems, converting sunlight into electricity. With the increasing adoption of solar technology in residential and commercial spaces, ensuring the safety and reliability of PV modules becomes paramount.
As solar modules generate power on the roof, they are exposed to a myriad of environmental elements and even potential fire hazards. Although solar panels catching fire is an uncommon occurrence, it is vital to ensure they can withstand such risks.
To evaluate the fire resistance of PV modules, the International Electrotechnical Commission (IEC) has developed a comprehensive standard for fire testing PV modules: IEC 61730-2. This standard is based on the American fire tests for roof coverings according to ANSI/UL 790.
Understanding the IEC 61730-2 Standard
The IEC 61730-2 standard classifies the PV module into three categories: Class A, Class B, and Class C, with Class C comprising the minimum fire resistance requirements. The standard mandates PV modules to undergo two critical tests to assess their fire safety:
Spread of Flame Test
The Spread of Flame Test evaluates the flame spread on the top surface of the PV modules and between the roof covering and the PV modules assembled on the roof. During the test, a gas flame is directed over the surface of the PV elements while they are exposed to wind. The burner rating and flame exposure period vary depending on the module class:
Burner rating: 325 kW
Flame exposure period: 4 min
Class A or B:
Burner rating: 378 kW
Flame exposure period: 10 min
To ensure comprehensive evaluation, a total of three modules undergo the Spread of Flame Test. These modules are tested individually as well as in an array when connected together.
Burning Brand Test
The Burning Brand Test examines whether an external fire can ignite PV modules or lead to complete burn-through. In this test, inflamed wooden brands are placed on a module assembled on the test rig under wind exposure. The class rating in A, B, and C is based on the weight of the wooden brands and the number of individual tests.
Key requirements according to IEC 61730-2 are as follows:
No burning or glowing part of the PV module should fall off the test rig.
The flame spread should not exceed: Class A – 1.82 m, Class B – 2.40 m, & Class C – 3.90 m.
The lateral flame spread should be limited.
While IEC 61730-2 provides a comprehensive framework, additional requirements to pass the fire test may vary among countries. For instance, certain countries may prohibit the use of PV modules that develop holes due to burns or modules that burn continuously during the Burning Brand Test.