GSE Approved Solar Panels UK: Latest KIWA MCS012 Module List Explained
- Nick Lundie
- May 18
- 5 min read
For some time, UK solar installers using GSE in-roof mounting systems faced a frustrating issue: the wider solar panel market had moved on to larger, higher-output modules, but many of the panels listed on the official GSE MCS012 certificate were older, lower-wattage models.
In practical terms, this meant that a modern 470W+ solar panel might have been readily available from wholesalers, and it may even have physically fitted the GSE tray, but that did not automatically mean it was approved for use as part of an MCS-compliant in-roof installation.
The latest GSE/Kiwa MCS012 certificate is therefore an important update for installers, designers and customers. It includes newer, higher-output PV modules, including selected panels above 470W, giving more flexibility when designing compliant in-roof solar PV systems in the UK.
But the reason for the delay was not simply panel size, weight or mechanical mounting. The main issue was fire classification.
Why GSE Approved Panels Matter
GSE is a popular in-roof solar mounting system used across the UK. Unlike an on-roof mounting system, where solar panels sit above the existing roof covering, an in-roof system replaces part of the roof covering.
This means the solar panels, trays and surrounding roof build-up become part of the roof structure. Because of this, the system must be assessed not only for how it is fixed to the roof, but also for how it performs in relation to external fire spread.
For MCS-compliant installations, it is not enough to say that a solar panel physically fits the tray. The panel must be covered by the relevant certification evidence for the complete roof-integrated system.
That is why the approved panel list on the GSE/Kiwa MCS012 certificate matters.
The Real Reason Behind the Delay in New High-Wattage Panels
For a long period, installers noticed that many of the panels listed for use with GSE in-roof systems were around the 400W to 440W range. At the same time, the solar industry was rapidly moving towards larger, higher-output modules, including panels above 470W.
This created a gap between what was available in the market and what could be confidently specified for a compliant GSE in-roof installation. The delay was not mainly because higher-wattage panels were too heavy, or because manufacturers had stopped innovating. The bigger issue was around external fire classification for roof-integrated solar systems.
With an in-roof system, the PV module and mounting tray form part of the roof covering. This means the system needs suitable evidence for external fire performance, commonly referred to as BROOF(t4) classification. MCS highlighted an industry-wide challenge around solar PV module fire classification. Changes to the relevant European standards affected the way fire test laboratories could issue classifications for roof-integrated solar systems. In simple terms, new PV modules could not just be added to the approved list because they were newer, more efficient or physically compatible. They needed to be covered by valid fire classification evidence as part of the tested roof system.
This is why many newer high-wattage panels were delayed from appearing on approved lists for in-roof systems.
What Is BROOF(t4)?
BROOF(t4) is an external fire performance classification used to assess how a roof system performs when exposed to fire from outside the building. For roof-integrated solar PV systems, this is especially important because the solar panel and mounting system are not simply installed above the roof covering. They effectively become part of it.
This is why fire classification is such a key part of the approval process for in-roof solar systems.
For homeowners, this means that the choice of solar panel is not just about wattage, efficiency or appearance. The selected module also needs to be suitable for the roof-integrated mounting system being used. For installers, it means checking the latest certificate before specifying a panel. A number of installers were fitting newer panels and crossing their fingers that they would eventually be pushed through the testing process. This was ill-advised and not something we as a company were willing to do.
What Has Changed with the Latest GSE/Kiwa Certificate?
The latest GSE/Kiwa MCS012 certificate includes a wider list of PV modules, including selected newer high-wattage panels above 470W.
This is a positive step for the UK solar industry because it brings the approved panel list closer to the panels that are now commonly being used in modern solar PV designs.
Higher-output panels can offer several benefits:
More power from the same roof area
Fewer panels required to achieve the same system size
Reduced mounting and wiring requirements in some designs
Better options for smaller or more complex roofs
Improved design flexibility for installers and customers
However, it is important to understand that not every 470W+ panel is automatically approved for GSE in-roof systems. Only the specific modules listed on the current certificate should be treated as approved.
Why This Matters for Homeowners
If you are having an in-roof solar system installed, the approved panel list matters because it helps ensure the system has been designed using components that are suitable for that specific mounting system.
A good installer should not simply choose a panel based on price, availability or wattage. They should check that the selected panel is listed for use with the in-roof mounting system being installed.
This helps protect the quality, compliance and long-term suitability of the installation.
For homeowners, the key question to ask is:
“Is the solar panel being installed listed on the current GSE/Kiwa MCS012 certificate?”
If the answer is unclear, it is worth checking before the installation goes ahead.
Practical Checks Before Using a High-Wattage Panel with GSE
Before specifying or installing a newer high-output panel with a GSE in-roof system, installers should check:
The exact panel manufacturer and model number
The current GSE/Kiwa MCS012 certificate
Whether the panel is listed in the approved module appendix
The panel dimensions and mounting requirements
Roof loading and structural suitability
Electrical design, including string sizing and inverter compatibility
Any manufacturer-specific installation instructions
The latest MCS and Building Regulations requirements
These checks help ensure the installation is not only high-performing, but also suitable for a compliant UK in-roof solar PV system.
Where to Find the Latest GSE Approved Panel List
The approved panel list is included within the current GSE/Kiwa MCS012 certificate.
The certificate includes the scope of approval, system details and the appendix of PV modules assessed for use with the GSE in-roof mounting system.
You can view the current GSE/Kiwa MCS012 certificate here:
Because certificates can be updated, we always recommend checking the latest version directly before final design or installation.
Final Thoughts
The latest GSE/Kiwa certificate update is a positive development for the UK solar industry.
For a long time, installers were limited by an approved panel list that did not fully reflect the newer, higher-output modules available in the market. The inclusion of selected 470W+ panels gives installers and customers more flexibility when designing GSE in-roof solar systems.
The key point is that panel choice for in-roof solar is not just about wattage, size or availability. The selected module must be covered by the relevant certification evidence for the mounting system being used.
At Lundie Electrical, we check the latest GSE/Kiwa MCS012 certificate before specifying panels for GSE in-roof installations. This helps ensure that the panels we install are not only efficient and well-suited to the property, but also appropriate for a compliant UK solar PV installation.
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