An update on Solar PV Module fire classifications

24 October 2024

Late last year the MCS Solar Mounting Working Group became aware of a change to a European standard, that took effect in September 2023. This change meant that fire test laboratories were no longer in a position to issue a fire classification for solar PV modules.

Some solar PV products require a fire classification for certification against The Solar Mounting Product Standard (MCS012). More importantly, where solar products form a roof covering (i.e. roof-integrated) a fire classification is required so that compliance with Building Regulations can be demonstrated (specifically Regulation B4: External fire spread).

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. This also prevents them gaining MCS certification.

Overview

The fire classifications that can be issued for construction products are defined in BS EN 13501-5 and relate to test methods set out in CEN/TS 1187:2012. So, for example, a classification of Broof (t4) is based upon Test 4 of CEN/TS 1187:2012.

Both BS EN 13501-5 and CEN/TS 1187 apply specifically to construction products, as defined in the Construction Products Regulations. Solar PV products are not listed as construction products in those regulations. This was not previously an issue because test laboratories were able to use their own expert opinion for extended application (EXAP), according to the principles set out in BS EN 15725, to extend the testing scope of CEN/TS 1187. However, BS EN 15725:2023, which took effect in September 2023 (because the previous version was withdrawn) removed expert opinion as a process that could be used for EXAP.

Approved Document B currently details a transposition table (Table B2) between classifications according to BS EN 13501-5 and BS 476-3 so presents a possible solution, as the changes to BS EN 15725:2023 do not apply to BS 476-3 so in theory extended application of the test is still possible with expert opinion. However, it is the intention of the UK Government to remove this transposition table from Approved Document B so only classifications according to BS EN 13501-5 will be valid, closing off a potential interim solution.

What has MCS done to assist?

Despite this not being an issue originating from MCS, MCS has convened several meetings since this was brought to our attention with representatives from the Building Safety Regulator, the Northern Irish, Welsh and Scottish governments, fire test laboratories and BSI (specifically the Chair and Secretariat for FSH22-8 as the committee responsible for BS 476-3). The aim of these meetings has been to determine a solution.

MCS has stressed to those present in the meetings that there was an urgent need for a solution as, without one, the UK’s deployment of solar PV could be harmed.

Possible solutions

As Approved Document B will remove reference to BS 476-3 there is a question over a transition period. So, there is still 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 whilst representations are made to the European committee responsible for BS EN 15725.

MCS is currently (and urgently) seeking:

· A response from BSI as regards the possibility of updating BS 476-3 (or re-writing a version of it) to better apply to solar PV products.

· Clarification from the Ministry of Housing, Communities and Local Government (MHCLG) regarding the transition period for the removal of BS 476-3 from Approved Document B.

MCS will issue further updates as this evolves.