Photo-Voltaic (Solar Array) Installation Fire
When a large photo-voltaic (PV) array (or Solar Array) catches fire on the rooftop of a manufacturing facility, several months after the installation was placed into service, it brings an array of difficulties; several millions of dollars in losses related to direct fire damage, business interruption, and the inability to offset utility costs via the solar array until it could be placed back into service.
S-E-A was asked by the insurer of the manufacturing facility to conduct an electrical evaluation of the fire-damaged solar array and determine the cause of the fire.
How does a large solar array catch fire and cause severe damage only several months after installation?
S-E-A was asked to conduct an electrical evaluation to determine the cause of the fire.
To perform the analysis, S-E-A took the following steps:
- The fire-damaged solar modules and associated wiring were electrically traced and were collected for further examination.
- Un-damaged portions of the solar installation were documented and collected as examples of the installer’s work product.
- Relevant fault logs were downloaded from the solar inverters.
- Computed Tomography (CT) scans were acquired of several of the PV connectors used to interconnect modules within the array.
- Research was conducted on the proper method of assembling and connecting PV connectors in the field.
Evidence was evaluated resulting in the following findings:
- The solar array installer did not use the proper crimping tool when assembling connectors in the field. This resulted in connectors that were more susceptible to degradation over time, and that could ultimately lead to resistive heating.
- The fire was caused by resistive heating of a field-assembled connector that ignited the rooftop membrane.
- Although the solar inverter identified arc faults—an indication of solar array wiring degradation—in the days preceding the fire, the solar array maintenance contractor subsequently disabled this feature, allowing the wiring to continue to degrade and ultimately cause the fire.