Rise Fire Research, an institute in Norway, has conducted a series of experiments indicating that the distance between solar modules and rooftop surfaces could be a crucial factor in PV system fires.
“We have not found any single ideal distance between the roof and the PV modules that can prevent fire propagation,” researcher Ragni Fjellgaard Mikalsen told pv magazine. “But we have seen that the gap distance is one of several parameters that affect the fire spread.”
The scientists said that wind speed and air gap size could affect the development of fires in the space between solar modules and the underlying roof structures. They also looked at how fires could affect PV systems on real, pitched rooftops in Norway. They performed 29 experiments at the institute's facility in Trondheim in 2021.
The research group identified a link between the size of the gap between a rooftop surface and the modules, and determined how big an initial fire would have to be for the blaze to spread and become larger.
“These, and other experiments, point to that a larger gap distance decreases the flame propagation, but other parameters, like inclination, ignition source, combustible materials can also affect the fire dynamics in the air gap,” said Fjellgaard Mikalsen.
She claimed that there are no testing methods or standards that properly consider the interplay between PV modules and building surfaces.
“The test methods for building materials are not including the possibility to add PV modules, and the test methods for PV modules are not considering what building surface they should be installed on,” she said. “For building integrated PV modules, the modules need to comply with both the regulations for building materials and as an electrical installation.”
She said that the modules were tested against one of the four European test methods listed in CEN/TS 1187, but noted that these test methods are not particularly well-suited to test PV modules.
“The American test standard UL 1703 / UL 61730 includes some fire tests where the combination of roofing material and PV installation is handled,” she said. “These are based on the test for roofing materials UL 790 where the roof is exposed to an external flame.”
The scientists said that future standards for Norwegian PV installations should be harmonized on a European level, and preferably globally.
“Ideally, the test standards should consider the interactions between the building surface and the PV modules and test the systems at a sufficiently large scale to include the important details of the building surface, fixing system and PV modules,” Fjellgaard Mikalsen said. “To be able to document the fire performance of different combinations of roofing materials, fixing systems and PV modules, a structured classification scheme could be developed.
A similar study, published by the University of Edinburgh and the Technical University of Denmark, showed similar results. The scientists analyzed fire dynamics and flame spread on the substrate beneath panels. They concluded that the shorter the distance between the panels and rooftop, the higher the probability of larger and more destructive fires.
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This article does not identify UL 2703 (UL Standard for Safety for Mounting Systems, Mounting Devices, Clamping/Retention Devices, and Ground Lugs for Use with Flat-Plate Photovoltaic Modules and Panels) that has testing requirements for a system fire class rating of mounting systems with modules or panels in combination with roof coverings.
Flammable EVA is the cause of fire spread. Silicone encapsulation isn’t. energyideas
I’m having to spend a very painful amounts on 3 story scaffolding, cleaning & side barriers, after up to 20 noisy pigeons set up their perfect home under my solar panels.
My power output dropped due to droppings & my gutters are blocked.
I can’t understand how panels can be allowed to be installed without side skirts.
The fact that panels without side skirts so obviously funnels fires, adds to my puzzlement.
It would be such a cheap thing to do, if done during the instalation. If government regulations aren’t being considered, perhaps building insurance surcharges would nudge installers to offer to add skirts?
The real chance of a solar array causing a fire is very low. Side skirting as noted above would alleviate the animal damage..as does the array being installed on a steel roof. My array does not have skirting…animals and birds do not like my steel roof…other advantages are the life time warranty of the roof and the fact it is non combustible. A win win for a rooftop array.
Maybe stop building roofs of highly flammable oil byproducts? 🙂
I want a fire probability of exactly 0. Can’t imagine not needing a stiff breeze under panels, can’t imagine squirrels not messing with the situation. Need just enough FR agent released at a time to put out the 🐿️ who didn’t plan for 370V…
This article did not discuss the causes of fires affecting PV systems, whether originating within the system itself or interacting with the system from a source within or near the dwelling where the system is installed. A comment in response to the article raised yet another factor, which is animal incursions and interactions as well as structural measures to deter them. Answers to all these questions would be of significant value in fostering the practical application of such systems, both in initial construction design and as additions to existing construction.
I would like more solar panels now that I installed a heat pump system for my space heating. Waiting for products and solutions to become more plug and play and building part integrated. My dream system would be a semi transparent modular awning system for a south facing nitche in my back yard mated to a battery backup capable of running my heating system at night and perhaps my hot water and or water pump in the daytime with ability to disconnect from the grid in case of emergency. My present system inverter is not high enough capacity to handle enough new panels and the fire potential would be greatly reduced by glass free standing modules.
One solution to fires from debris under solar panels would be to seal the gaps between the panels, making them the roof. Yesterday I was at Addison Road Community center in Sydney, where they have a two car charger, with parking for two cars, under a waterproof PV roof.
I am a volunteer firefighter and the biggest issue we see with PV panels is build up of debris (Leaves, windthrow etc) under them. This makes them very vulnerable to ember attack if there are any wild fires in the area. Unfortunately in the fire season the debris can build up quickly making it difficult for property owners to remove debris . What we would like to see are panel mount solutions that prevent the build up of debris like this under and around the panels ..
Does a “chimney” effect not apply. The London underground wooden escalator fire might have some relevance.