MCS 012 solar mounting standard

MCS 012 is the MCS product standard for equipment used to mount solar PV modules and solar thermal collectors on building roofs. It covers both complete mounting systems and identifiable components.

It is product certification, not a site-specific structural design and not an installation certificate. A certified product still has to be suitable for the actual roof, loads, module and layout, and it has to be installed within the limits on its certificate and instructions.

Current edition and scope

As at 22 July 2026, the current published edition is MCS 012 Issue 3.0, dated 10 May 2023. It became mandatory for products certified to MCS 012 from 10 May 2025.

Its scope includes:

• systems that hold panels above an existing roof covering
• systems in which panels or mounting components replace some or all of the roof covering
• PV tiles and other active solar products bonded to a roof-covering product
• complete systems and individual components such as hooks, rails, clamps and rafter bolts

An active PV product that forms part of the roof can also require certification to MCS 005. Products whose only purpose is flashing around an above-roof bracket are outside MCS 012, as are products relying solely on site-applied sealant for their weather seal.

The standard distinguishes two attachment types:

• mechanically attached systems are screwed, bolted, clamped, bonded or welded to the roof structure or covering
• non-mechanically attached systems rely on ballast, aerodynamic effects or both

This is worth checking because “bonded” is sometimes described as a separate class. In MCS 012 Issue 3.0 it sits within mechanically attached systems.

What certification establishes

The certification body reviews test reports, the technical file and the manufacturer’s factory production control. The certificate can cover a complete system or defined individual components, and must state the product identity and certified performance data.

The core technical objectives are to establish:

• maximum design resistance to wind uplift
• the applicable roof fire classification with the mounting equipment in place
• that the equipment does not reduce the roof’s long-term resistance to weather
• the products, roof types, fixings, spacing and layout limits covered by the instructions

MCS 012 does not provide a generic “safe on every roof” result. For example, the declared uplift resistance is an input to the project’s wind design. It does not establish the wind load at a particular address or prove that the roof structure can carry the array.

Weather resistance and roof loads

Where hooks or brackets are used with fragile coverings such as slate, clay tiles or concrete tiles, they must either avoid transferring load to the covering or demonstrate that an evenly distributed load will not damage it. Products using a factory seal or gasket may also specify a compatible site-applied sealant, but a seal made solely from site-applied sealant is not eligible for MCS 012 certification.

These product requirements do not replace the building assessment under MIS 3002. The installer still needs evidence that the roof can carry the imposed loads and that the finished penetrations, tiles, flashings and drainage remain weather-tight.

Fire classification and roof-integrated PV

Where a panel or mounting system forms part of the roof covering, fire performance applies to the roof construction that was assessed. A certificate or classification can therefore be limited to particular modules, trays, substrates and build-ups.

Do not assume that an MCS 005 certificate for a PV module and a separate MCS 012 certificate for a mounting product automatically prove that any combination of the two is covered. The certificate and installation instructions need to include the proposed combination or give an applicable compatibility route.

MCS reported a separate classification problem following the withdrawal of the expert-opinion route previously used to extend some external-fire test results. That is a current standards issue, not a reason to accept an unclassified roof-integrated build-up. Where fire classification is required, its scope must match the proposed roof construction.

Flat roofs and the MIS 3002 alternative route

Issue 3.0 expanded MCS 012 to include mounting equipment for flat roofs, including non-mechanically attached systems on roofs with a pitch of 10 degrees or less. Certification difficulties then left too few suitable products available for some projects.

As at 22 July 2026, MCS’s published position continues the relevant MIS 3002 alternative route for flat-roof installations until further notice while MCS 012 is reviewed and sufficient products complete certification. The two current MIS 3002 scheme tracks express the project-specific mounting exception in their own documents, so an installer should use the clause belonging to its scheme and edition rather than relying on an old clause number copied from guidance.

This is not a general exemption from design evidence. Where no suitable MCS 012 system exists, MIS 3002 requires the contractor to retain project-specific evidence addressing structure and wind loading, fire and weather performance, component compatibility and correct installation. A ballasted flat-roof system also requires a qualified structural engineer to confirm the roof can carry the array and ballast loads.

How to check a proposed system

Ask for the current certificate, not just a logo or product name. Check:

• the certificate number and live status in the MCS Product Directory
• the exact product, component revisions and manufacturer
• the roof type, pitch and attachment method within scope
• the proposed module or the certificate’s module-compatibility rules
• maximum module dimensions, fixing quantities, spans and layout limits
• declared wind-uplift resistance and the separate site wind calculation
• any fire classification and the roof build-up to which it applies
• the current installation instructions

If the installer is using the MIS 3002 alternative instead, ask for the actual structural, wind, fire, weather-tightness and compatibility evidence in the project file. “Custom designed” should describe a documented design, not an undocumented collection of parts.

What MCS 012 does not prove

MCS 012 certification does not by itself prove:

• that the existing roof is sound
• that the structure can carry this array
• that the site wind and snow loads have been calculated correctly
• that the installer used the certified combination or followed its limits
• that Building Regulations and planning requirements have been met
• that the finished roof is free from installation defects

Those questions sit with the site assessment, MIS 3002 installation process, Building Regulations and the evidence retained at handover.

Related entries

• MIS 3002 solar PV standard
• MCS
• In-roof solar mounting
• Flat roof ballast systems
• Structural roof assessment for PV
• Wind loading for PV arrays