MCS published an industry news article on 24 October 2024 describing a fire-classification problem affecting solar PV modules and the work it has undertaken towards a solution1. The issue dates from a change to a European standard that took effect in September 2023, which MCS says left fire test laboratories unable to issue a fire classification for solar PV modules1.
Fire classifications for construction products are defined in BS EN 13501-5 and relate to test methods in CEN/TS 1187:2012; a classification of Broof (t4), for example, is based on Test 4 of that standard1. Both documents apply specifically to construction products as defined in the Construction Products Regulations, and MCS states that solar PV products are not listed as construction products in those regulations1. That was not previously a problem because laboratories could use their own expert opinion for extended application (EXAP) under BS EN 15725 to extend the testing scope of CEN/TS 11871. MCS reports that BS EN 15725:2023, which took effect in September 2023 because the previous version was withdrawn, removed expert opinion as a process that could be used for EXAP1.
The practical effect, according to MCS, is that any new products brought to market are currently unable to obtain a fire classification and therefore cannot be integrated into roofs in compliance with the Building Regulations, which also prevents them gaining MCS certification1. A fire classification is required where solar products form a roof covering, so that compliance with Regulation B4 on external fire spread can be demonstrated1. Some solar PV products also require a fire classification for certification against the Solar Mounting Product Standard, MCS0121. The requirements sit alongside the wider MCS certification for solar PV installations framework.
Approved Document B currently sets out a transposition table, Table B2, between classifications under BS EN 13501-5 and BS 476-3, which MCS describes as a possible solution, since the changes to BS EN 15725:2023 do not apply to BS 476-3 and extended application of the test is in theory still possible with expert opinion1. MCS adds that it is the intention of the UK Government to remove this transposition table from Approved Document B, so that only classifications according to BS EN 13501-5 will be valid, closing off a potential interim solution1.
MCS says it has convened several meetings since the issue was brought to its attention, with representatives from the Building Safety Regulator, the Northern Irish, Welsh and Scottish governments, fire test laboratories and BSI, including the Chair and Secretariat for FSH22-8 as the committee responsible for BS 476-31. It states it stressed an urgent need for a solution, as without one the UK's deployment of solar PV could be harmed1.
"MCS has convened several meetings since this was brought to our attention"
Why it matters for households
The classification question bears on products that form the roof covering itself, rather than panels mounted on top of an existing roof. For a household considering roof-integrated solar, the article indicates that new products reaching the market cannot currently obtain the fire classification needed to show Building Regulations compliance, and so cannot be integrated into roofs on that basis1. The same gap prevents those products from gaining MCS certification1, which is the route by which installations qualify for government incentives and which underpins the MCS certification process. The article does not state how many products are affected, whether any currently certified products are affected, or what the position is for panels mounted above an existing roof covering; none of this has been reported1.
What happens next
MCS states it is urgently seeking a response from BSI on the possibility of updating BS 476-3, or re-writing a version of it, to better apply to solar PV products, and clarification from the Ministry of Housing, Communities and Local Government on the transition period for the removal of BS 476-3 from Approved Document B1. It notes a possibility that testing and classification according to BS 476-3, in an edited form for the purpose of testing solar PV products, might form a temporary solution while representations are made to the European committee responsible for BS EN 157251. MCS says it will issue further updates as this evolves1. No dates for those steps are given1.
Sources1 cited
- An update on Solar PV Module fire classifications - MCS, mcscertified.com