Study highlights technologies designed to prevent fires in rooftop PV systems

FRAMINGHAM, USA: IDC Energy Insights announced at the IDC Energy Insights Clean Energy Outlook conference the availability of a new report, Technology Selection: Reducing Fire Risk in Rooftop Solar PV Systems that highlights the risk of fire in solar photovoltaic (PV) systems and features the technologies that help prevent those fires.

According to the research, rooftop solar PV systems offer a unique set of benefits to home and commercial building owners seeking a quiet, unobtrusive source of clean electricity.

However, the simplicity of PV systems, including their lack of moving parts and minimal maintenance requirements, makes it easy for system owners to overlook the risks that are associated with installing a power generator on a rooftop. One of those risks includes the potential for electricity to arc across an unwanted gap in the PV system's electrical circuit, thereby creating an arc-fault.

"The risk of fire must be taken into account when evaluating any electrical system that operates at high voltages and high power levels, and rooftop solar PV systems are no exception," said Jay Holman, research manager, IDC Energy Insights.

"Arc-faults pose the greatest fire risk. Detecting and extinguishing arc-faults in DC PV systems will require the development of new devices called DC PV Arc-Fault Circuit Interrupters (DC PV AFCIs), designed to detect the signature of an arc-fault in the current of a PV system and stop the current from flowing through the arc-fault."

The 2011 US National Electric Code (NEC) includes a requirement for arc-fault protection in certain new rooftop PV systems. In response, solar industry vendors are already developing technologies that not only meet this requirement, but go beyond it and provide additional protection against PV system fires.

However, efforts are being slowed by the lack of an industry standard against which to certify the new devices, as well as delayed adoption of the NEC by many states and jurisdictions. As a result, it could be months or years before the majority of new PV systems being installed in the US include these new protections.

"All too often, new fire safety requirements do not make it into the code until a tragic event raises awareness of risks to the national level. Arc-fault protection in rooftop PV systems serves as an example of how an industry can take proactive measures to prevent such tragedies from occurring," concluded Holman.

The IDC Energy Insights study details the different ways in which electrical systems can fail, the ways in which those failures can cause fires, and the steps to be taken to detect and mitigate those failures before a fire can occur. Comparisons are made between the well-documented risk of fires in household electrical distribution systems and the less understood risk of fires in rooftop solar PV systems.

The report reviews additions to the US 2011 National Electrical Code meant to address the risk of fire in certain types of rooftop PV systems and the impact of those changes on solar systems in the US is assessed. Finally, recommendations are made for solar industry vendors and solar PV system owners who must comply with the new requirements of the US National Electric Code.