MIS 3002 is the MCS standard that sets out how UK contractors must supply, design, install, commission, and hand over solar PV systems up to 50kWp connected in parallel to the distribution network, and a significant update to it became mandatory for certified installers on 18 June 2026 (MCS, 2026). Two parallel versions currently apply depending on which installer scheme a company sits under, which catches out contractors who assume there is only one document to check.
This guide walks through what MIS 3002 actually requires, why the June 2026 clause 5.5.5 update matters right now, how earthing and bonding decisions fit into the standard, and where MIS 3002 ends and the separate MCS 012 mounting product standard begins.
Key Takeaways
- MIS 3002 is the Solar PV Installation Standard, covering design, installation, commissioning, and handover for systems up to 50kWp connected in parallel to the grid.
- A clause 5.5.5 update published 18 March 2026 became mandatory for MIS 3002-certified installers from 18 June 2026, adding new evidence requirements for structural, fire, and weather-tightness performance (MCS, 2026).
- Two live versions exist in parallel: MIS 3002 V6.0 under the Current Scheme and MIS 3002:2025 V2.0 under the Redeveloped Installer Scheme, and installers need to confirm which applies to their certification.
- Earthing and bonding decisions for the array frame must be justified and recorded if protective or functional earthing is not provided, per the standard's referenced earthing and bonding decision tree.
- MIS 3002 governs installation process; MCS 012 governs mounting product certification, and clause 5.5.5 is the specific point where the two standards interact.
What MIS 3002 actually covers
MIS 3002 specifies the requirements for MCS-accredited contractors undertaking the supply, design, installation, set-to-work, commissioning, and handover of solar PV microgeneration systems on permanent buildings, up to a maximum DC output of 50kWp connected in parallel to the electricity distribution network (NBS, 2025). It references BS EN 62446-1:2016+A1:2018 for the testing, documentation, and inspection procedures that commissioning must follow, so the paperwork an installer produces at handover is not discretionary, it is a defined checklist tied to a British Standard.
The standard covers roles and competency requirements alongside the technical design rules, meaning a contractor's certification depends on more than just correct wiring. Design sign-off, system performance verification, and the customer handover pack are all assessed as part of the same standard, which is why gaps in paperwork show up during MCS surveillance audits as often as technical faults do.
Scope matters here too. Systems above 50kWp fall outside MIS 3002 entirely and are typically handled under separate commercial standards and grid connection processes, so an installer moving from domestic rooftop work into larger commercial arrays needs to check which framework actually applies before assuming MIS 3002 covers the job. Getting this wrong at the design stage tends to surface expensively later, once a DNO application or funding agreement has already been submitted under the wrong standard.
Why MIS 3002 changed in 2026
MCS updated clause 5.5.5 of MIS 3002 following a five-week consultation published in November 2025, specifically to address installations where no certified mounting system exists under MCS 012, the Solar Mounting Product Standard (MCS, 2026). The update clarifies Building Regulations guidance across devolved nations and expands what installers must evidence when using an uncertified mounting system.
Under the revised clause, installers now need to provide evidence covering four areas: completed structural and wind loading calculations specific to the mounting system installed, confirmation of how fire performance is maintained after installation, confirmation of how weather-tightness is maintained, and evidence that all system components are compatible with one another. Compliance became mandatory for MIS 3002-certified installers from 18 June 2026, which means any installer still working from pre-update paperwork templates as of this year is already out of step with the current standard.
The update also clarified language around manufacturer instructions, requiring written confirmation that the final installation follows them exactly rather than a general statement of intent. This closes a gap certification bodies had flagged repeatedly during audits, where installers referenced manufacturer guidance verbally on site but had nothing documented to show an assessor after the fact.
How does the structural and wind loading evidence requirement work in practice?
Installers using an MCS 012-certified mounting system generally satisfy this requirement through the product's own certification, since wind and snow loading has already been assessed for that product's certified range. The added burden falls on jobs using uncertified or bespoke mounting arrangements, where the installer must now produce their own structural and wind loading calculations specific to the property and mounting method before raising a compliant installation certificate.
This is a meaningful shift in accountability. Previously, clause 5.5.5 allowed more discretion for uncertified systems provided general Building Regulations requirements were met; the 2026 update replaces that discretion with a specific, documented evidence trail the installer must retain and be able to produce during an audit. Retrofit jobs on unusual roof geometries, where a standard MCS 012 product does not fit cleanly, are the cases most likely to trigger this requirement.
Two scheme versions of MIS 3002 are live at once
Two versions of MIS 3002 exist side by side because MCS is mid-transition between its legacy Current Scheme and the Redeveloped Installer Scheme. Installers certified under the Current Scheme work to MIS 3002 V6.0, while those who have already moved to the Redeveloped Installer Scheme work to MIS 3002:2025 V2.0, and both were published as final documents in March 2026 on the MCS Standards & Tools Library.
Checking which scheme a certification body has moved a company onto is not optional homework, since referencing the wrong version during an audit or a customer dispute undermines the paperwork trail entirely. Installers unsure which version applies should confirm directly with their certification body rather than assuming continuity from a previous renewal cycle, particularly if that renewal happened before the Redeveloped Installer Scheme rollout began. This same transition affects the underlying MCS accreditation process more broadly, not just the solar PV standard specifically.
The practical risk sits with jobs that straddle the transition date. A design signed off under one scheme version but commissioned after a company moves to the other can end up with mismatched paperwork, so installers mid-transition are better served by completing jobs under the scheme version active at design stage rather than switching mid-project. Earlier issues of the standard remain publicly archived for reference, including the pre-2025 issue used before the Redeveloped Installer Scheme work began (Green Book Live, 2025).
What does MIS 3002 say about earthing and bonding?
MIS 3002 requires that array frame earthing and bonding decisions be justified and documented, and if the system designer chooses not to provide protective or functional earthing, that decision must be recorded with reasoning rather than left implicit. This sits alongside BS 7671 Section 712, which addresses equipotential bonding for PV array frames and mounting structures directly (Excel Energy, 2025).
The IET's guidance uses an earthing and bonding decision tree to determine whether the DC side meets requirements for double or reinforced insulation, and whether the PV array frame counts as an extraneous or exposed conductive part, since the bonding requirement differs depending on that classification. DC-side cabling itself must be selected and installed to minimise the risk of earth faults and short circuits, typically through single-core cables with a non-metallic sheath, installed in line with Chapter 52 of BS 7671 (IET, 2025). Our guide to the IET Code of Practice for electrical energy storage covers the equivalent earthing considerations for battery systems fitted alongside solar arrays.
- Testing and documentation: Compliance with BS EN 62446-1:2016+A1:2018
- Array frame earthing: Justified and recorded decision if not provided
- DC cabling: Single-core, non-metallic sheath, per BS 7671 Chapter 52
- Uncertified mounting (clause 5.5.5): Structural, fire, weather-tightness, compatibility evidence
- Handover documentation: Full commissioning certificate raised within the MID's 14-day window
How does a solar PV commissioning certificate fit into MIS 3002?
The commissioning certificate is the practical output of following MIS 3002 correctly on a specific job. Once set-to-work testing and inspection are complete and documented per BS EN 62446-1, the installer raises the certificate in the MCS Installations Database within the standard 14-day commissioning window, and this becomes the customer's proof of a compliant handover, distinct from the company's own MCS installation certificate accreditation.
Certification bodies auditing against MIS 3002 look for consistency between the design documents, the on-site testing records, and the final commissioning certificate. Gaps between what was designed and what was actually tested and certified are one of the most common findings in surveillance audits, particularly on jobs where a late-stage design change was not reflected back into the paperwork.
MIS 3002 vs MCS 012: the actual difference
MIS 3002 governs the installation process end to end; MCS 012 is a separate product standard that certifies specific mounting hardware for structural and weatherproofing performance. An installer can be fully MIS 3002 compliant on workmanship and still fail an audit if the mounting system used was never MCS 012 certified and the clause 5.5.5 evidence trail is missing.
Clause 5.5.5 is the deliberate bridge between the two standards, covering exactly the scenario where a certified MCS 012 product is not available or suitable for a given roof. Understanding MCS standards as a layered system, rather than a single document, makes it much easier to see why an installer can pass one audit element and fail another on the same job. This distinction matters most on non-standard roofs, including many flat roof solar installations, where a certified mounting product might not exist for the specific membrane or loading profile involved, pushing the job straight into clause 5.5.5 territory.
Building control involvement adds a further layer that installers sometimes overlook. Structural changes tied to mounting systems can trigger separate notification requirements under Part P building regulations depending on the scope of electrical work involved, so the clause 5.5.5 evidence trail often needs to sit alongside, not instead of, standard building control paperwork.
Frequently asked questions
Does MIS 3002 apply to commercial solar PV systems as well as domestic?
Yes, MIS 3002 applies to any system up to 50kWp DC output connected in parallel to the distribution network, which covers most commercial rooftop and small ground-mount installations alongside domestic jobs, provided the system stays within that capacity threshold and connects to the grid rather than operating fully off-grid.
What happens if an installer uses an MCS 012-certified mounting system?
Using a certified mounting system generally satisfies the clause 5.5.5 evidence requirements through the product's own certification, since wind and snow loading data already exists for that certified range, reducing the paperwork burden compared with bespoke or uncertified mounting arrangements.
Is the MIS 3002 commissioning certificate the same as an MCS installer certificate?
No, the commissioning certificate is job-specific and raised per installation through the MID, while the installer certificate is a company-level accreditation renewed annually through a certification body. One authorises the company to work; the other proves a specific job was completed and tested correctly.
How quickly must a solar PV commissioning certificate be raised after installation?
Installers generally have a 14-day window from set-to-work testing to raise the commissioning certificate in the MID, and missing this window without contacting the MCS Helpdesk beforehand can complicate an otherwise straightforward compliant installation, sometimes requiring extra evidence to resolve retrospectively.
Do devolved nations have different MIS 3002 requirements?
The clause 5.5.5 update specifically added guidance covering Building Regulations variation across devolved nations, since England, Scotland, Wales, and Northern Ireland each maintain their own regulatory frameworks that the structural and fire performance evidence must satisfy on a nation-by-nation basis.
Reonic's design and commissioning tools help installers keep structural calculations, earthing decisions, and testing records aligned to the current MIS 3002 version before a certificate ever gets raised.
