The Causes of Solar Fires
There have been a small number of research studies aimed at establishing the root causes of solar fires, two of which are detailed below. Both found that faulty DC solar connectors were the source of a large proportion of the fires investigated.
Many solar professionals have been called to systems that are no longer working properly to find a near-miss, where burnt out connectors thankfully did not start a wider fire. Viridian Solar has enlisted two independent fire testing laboratories to conduct fire safety testing of ArcBox.
Building Research Establishment, 2018 (UK)
A 2018 study of solar fires in the UK by the Building Research Establishment (BRE), found 56 incidents that were likely to have initiated in the solar system. Of these, 22 were classified as serious fires – fires that spread beyond the point of origination – with the remainder being classified as ‘thermal events’ consisting of smoking and overheating.
Of the 56 fires:
- Between 26 and 28 of these were linked to the DC isolator
- Between six and 11 to the DC cables and connectors
- Six to nine at the inverter
- Two to five in the module
Following the research, regulations were tightened by the UK Microgeneration Certification Scheme (MCS). Since then, inverters have been launched with integrated DC isolators which removes this point of failure from new systems, leaving the DC connector as the most likely point of fire risk.
TNO, 2019 (Netherlands)
According to a TNO study of solar fires in the Netherlands, more than 80% of incidents investigated started with the DC connectors.
It is worth noting that this study was based primarily on interviews with insurance industry loss adjusters.
The higher focus on DC connectors as a source of claims in the TNO report, and the large number of ‘thermal events’ in the BRE study, suggest that DC connectors may result in more high-consequence fire events that involve insurance claims.