Fire rating of PV systems

The International Code Council (ICC) develops a family of building codes that pertain to photovoltaic (PV) installations.  They are the International Building Code (IBC), the International Residential Code (IRC), International Fire Code (IFC), and National Fire Protection Association (NFPA) 70, which includes the National Electric Code (NEC).

Every 3 years the codes are updated with the latest findings and research.  The latest versions of the IBC and IRC are 2012.

IBC Section 1509.7.2 includes requirements for fire classification of rooftop mounted PV systems.  IRC Section M2302.2.1 includes requirements for non-combustible or flame retardant materials.

The objective of the code is that the installation of a PV system doesn’t compromise the minimum fire safety requirements for the roof.

The language of this section states that the fire classification of PV systems must match the minimum fire classification of the roof assembly over which it is mounted.  However, PV modules are components of PV systems and, although PV modules can receive a fire rating in accordance with UL 1703, there is presently no American National Standards Institute (ANSI) classification test or fire rating for a PV system.

In the absence of a fire rating for PV systems, it may seem appropriate to use the fire rating of the PV modules in order to ensure the desired result of retaining the roof assembly’s original fire classification.  This is what some Authorities Having Jurisdiction (AHJ) have done.

Most PV modules have Class C fire rating, while some have an A rating.  This requirement, as interpreted and applied by some AHJ, effectively eliminates modules with a Class C fire rating from consideration in rooftop systems.

Extensive testing has been ongoing since 2008 in fire testing of PV modules as part of a PV system installed on a roof.  Currently technical working groups of SolarABCs, UL, ANSI, and other stakeholders are developing standards through which a fire classification for PV systems can be adopted.  Until those standards are developed, vetted, and adopted the requirements of IBC 1509.7.2 cannot be easily applied.

Look for new standards to be included in the latest version of the IBC in 2015.

For more information see the white paper by Solarabcs using the link below:

Impacts on Photovoltaic Installations of Changes to the 2012 International Codes