Update on Solar PV Flat Roof Mounting Systems

MCS HAS issued an update on solar PV flat roof mounting systems following changes to The Solar Mounting (Product) Standard.

Now that The Solar Mounting (Product) Standard allows for the certification of flat roof mounting systems, clause 5.5.5 in The Solar PV Installation Standard will no longer be acceptable as a means of compliance for flat roof installations.

On 10 May 2023, MCS published an update to The Solar Mounting (Product) Standard (MCS 012 v3.0). One of the changes to the standard was the expansion of scope to include mechanically attached and non-mechanically attached mounting systems designed for installation on flat roofs (≤ 10°).

Prior to this expansion of scope, installers utilised clause 5.5.5 in The Solar PV Installation Standard (MIS 3002) to ensure that in the absence of certified flat roof mounting systems, products installed on a flat roof were compliant. Clause 5.5.5 states:

“Where there are no MCS 012 certified mounting systems suitable for a given installation, a custom designed mounting system may be used subject to the following being met: a) The system is compliant with current Building Regulations for weather-tightness, fire and wind resistance. b) The system designer and/or fixing supplier must confirm in writing that the final installation is in accordance with a) above and its instructions.”

Clause Extension

Based on recent feedback from industry, MCS says it is aware that a number of manufacturers are still in the process of gaining certification for their flat roof mounting systems. To support manufacturers in gaining product certification to the updated Solar Mounting (Product) Standard, and to avoid installers temporarily being unable to access certified products for flat roofs, MCS is granting an extension of the use of clause 5.5.5.

The current interpretation of clause 5.5.5 in relation to flat roofs will be permitted until 10 August 2025. This will enable installers to register the installation of an uncertificated solar mounting system on the flat roof of a permanent building, subject to meeting the requirements stated within clause 5.5.5.

MCS is hosting its next Solar PV technical working group meeting on the 12 May 2025 where clause 5.5.5 will be reviewed. The organisation says details of the outcome of this review will be provided in due course.

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