Mitigating Thermal Events in Solar PV Systems
SUMMARY
This case study explores a thermal event inspection carried out by Clean Energy Associates (CEA) at a rooftop solar PV installation. CEA found the access to the roof was unsecured that allowed unauthorized cleaning of the site prior to the start of the investigation.
82% of issues identified by CEA posed a fire-life safety risk. This case study underscores the importance of rigorous installation standards and regular inspections to prevent potential safety hazards in solar PV systems.
THE SITUATION
A thermal event at a 1 MW PV rooftop system prompted an urgent need for a comprehensive site inspection to identify and rectify the root causes of the reported fire. The client required a detailed assessment to ensure the system's safety and functionality were not compromised, and to prevent future incidents.
The area post-clean up, showing repaired roof services and cleared debris.
THE FINDINGS
Thermal Event Investigation:
The thermal event site had been cleared of debris, and the roof had been repaired before CEA’s arrival on site, which may have led to tampering of evidence. Furthermore, CEA found damaged equipment, including cables, rapid shutdown devices (RSDs), and modules, in nearby dumpsters. It is very important to de-energize the site for safety reasons and secure the access to the site for unauthorized personnel.
CEA found the thermal event evidence with the burned RSDs exposed in the dump container near the main ground equipment.
Risk Identification:
CEA performed a visual inspection of the site, which covered all accessible areas and associated hardware of a PV system.
Based on the issues observed on the system, CEA identified damaged insulation of the DC cable as a potential cause of the thermal event. CEA also observed other major issues leading to improper assembly of the connectors. During the inspection, 11 risks were identified. 9 of these risks (82%) were classified as major. CEA’s finding risk potential is described as major when it is a fire-life safety risk.
The string wires were pinched under the ballast blocks across site.
The cables and wires sitewide had a bend radius beyond permissible limits.
Several open connectors were exposed to environmental elements.
