EN 1090-1 Solar Carport Frames: What EPCs Need to Know
- Keith Lin
- Mar 24
- 6 min read
Updated: Apr 9
Last updated: 24 March 2026
EN 1090-1 is the harmonised European standard governing the conformity assessment of structural steel and aluminium components. For EPC contractors specifying or installing commercial solar carports in the UK, using EN 1090-1 certified frames is not optional — it is a legal requirement under the Construction Products Regulation (CPR) and UK building regulations.
What Is EN 1090-1?
EN 1090-1:2009+A1:2011 (BS EN 1090-1 in the UK) sets out the requirements for conformity assessment of structural steel and aluminium components and kits. It is the "gateway" standard that allows manufacturers to issue a Declaration of Performance (DoP) and apply CE marking (or UKCA marking for the GB market) to their products.
The standard operates alongside EN 1090-2 (technical requirements for steel structures) and EN 1090-3 (technical requirements for aluminium structures). Together, they form a complete framework for manufacturing, quality control, and traceability of structural metalwork.
Key point for EPCs: If a structural steel or aluminium component is placed on the UK market and falls within the scope of the Construction Products Regulation, it must be CE or UKCA marked under EN 1090-1. A solar carport frame is a structural steel component. There is no exemption.
Source: BS EN 1090-1 — BSI Group
UKCA vs CE Marking: The Current Position
Since the UK left the EU, the regulatory landscape for construction products has been transitioning:
CE marking remains valid for structural steel and aluminium products placed on the GB market. The UK government has extended recognition of CE marking beyond the original June 2025 deadline.
UKCA marking is the UK's own conformity assessment mark. Manufacturers can choose to UKCA mark their products for the GB market.
For products placed on the Northern Ireland market, CE marking is required under the Windsor Framework. For export to EU member states, CE marking is mandatory.
What this means for EPCs: When you receive a solar carport frame kit, check that it has either a valid CE or UKCA Declaration of Performance. Both are currently accepted for structural steelwork placed on the GB market.
Source: UKCA Marking — SteelConstruction.info
The Four Execution Classes
EN 1090-2 defines four Execution Classes (EXC1 through EXC4) that specify the level of quality control required during fabrication. The execution class is determined by the consequence class of the structure, the service category, and the production category.
EXC1 — Basic
Suitable for structures where failure would have low consequence. Typically agricultural buildings, temporary structures, and non-occupied structures. Not appropriate for solar carports — carports are located in areas where people and vehicles are present.
EXC2 — Standard
The most common execution class for commercial construction, including solar carports, office buildings, retail units, and industrial premises. Requires documented welding procedures, welder qualifications, and systematic inspection. This is the standard for commercial solar carports. KLY Solar manufactures all frame kits to EXC2.
EXC3 — Enhanced
Required for structures where failure would have high consequence — bridges, multi-storey buildings, grandstands, and structures supporting large numbers of people. Rarely required for solar carports unless the structure supports additional loads.
EXC4 — Stringent
Reserved for critical structures where failure would be catastrophic — major bridges, nuclear facilities, and structures specifically classified by the designer. Not applicable to solar carports.Factory Production Control (FPC): Why It Matters
EN 1090-1 requires manufacturers to operate a certified Factory Production Control (FPC) system. FPC is a permanent internal quality control system that covers:
Material traceability — every piece of steel used in your carport frame can be traced back to the mill certificate.
Welding quality — all welding is performed to documented Welding Procedure Specifications (WPS) by qualified welders.
Dimensional accuracy — fabricated components are checked against design tolerances.
Surface treatment — galvanising, painting, or other protective coatings are applied to specified standards.
Non-conformance management — a documented process for identifying and resolving quality issues.
The FPC system must be audited and certified by an accredited Notified Body (for CE marking) or Approved Body (for UKCA marking). This audit is not a one-off — it is repeated at scheduled intervals, typically annually.
Why EPCs should care: FPC certification is your assurance that the frame kit you are installing was manufactured under controlled conditions with full traceability. If a structural issue arises on site, FPC documentation provides the audit trail you need to resolve it. Without FPC, you have no chain of evidence — and significant professional liability exposure.
What an EPC Should Receive from the Frame Kit Supplier
When KLY Solar delivers a solar carport frame kit, the following documentation is included:
1. Declaration of Performance (DoP)
The DoP is the legal document issued by the manufacturer under EN 1090-1. It declares the essential characteristics of the product — the execution class, the steel grade, the structural design basis, and the reference standards. Without a DoP, the product cannot legally be placed on the UK market.
2. Structural Engineering Calculations
A full set of structural calculations prepared by a chartered structural engineer (CEng or IEng), covering dead loads, imposed loads, snow and wind loads (calculated to BS EN 1991-1-4), foundation design, and connection design.
3. General Arrangement Drawings
GA drawings showing the overall layout, dimensions, column positions, beam spans, and panel zones. These are the primary reference for site setting-out.
4. Fabrication Drawings
Detailed drawings for each fabricated component — columns, rafters, purlins, bracing, connection plates. These show exact dimensions, hole positions, weld details, and surface treatment specifications.
5. Installation Guide
Step-by-step installation instructions covering foundation preparation, column erection, beam installation, purlin fixing, and panel mounting. Includes torque specifications for structural bolts and alignment tolerances.
6. Material Certificates
Mill certificates (EN 10204 Type 3.1) for all structural steel, confirming the grade, chemical composition, and mechanical properties of the steel used.Common EPC Mistakes to Avoid
1. Accepting Frames Without EN 1090-1 Certification
Some suppliers offer structural frames without EN 1090-1 certification — particularly imports from outside the UK and EU. These products cannot legally be placed on the UK market and expose the EPC to prosecution under the Construction Products Regulation.
2. Ignoring the Execution Class
Specifying EXC1 for a commercial solar carport to reduce cost is a false economy. If a structural failure occurs in an occupied car park, the EPC and the designer bear liability. EXC2 is the minimum appropriate class.
3. Not Checking Welder Qualifications
Under EXC2, all welders must hold valid qualifications to BS EN ISO 9606-1 for the specific welding processes used. Ask your supplier for copies of welder qualification certificates.
4. Foundation Design Mismatch
The structural calculations are only valid for the specified foundation type. If site conditions require a change (e.g., from pad footings to piled foundations), the structural engineer must recalculate. Do not modify foundation designs without engineering sign-off.
5. Skipping the Handover Documentation
Building Control will require the DoP, structural calculations, and material certificates at handover. Assemble these documents during construction, not after. Missing documentation can delay practical completion and final payment.
How KLY Solar Supports EPCs
KLY Solar operates a supply-only model specifically designed for EPC contractors. We manufacture the structural frame kit — you install it with your own team.
What we provide: EN 1090-1 certified hot-dip galvanised steel carport frames (EXC2), full structural engineering package (calculations, GA drawings, fabrication drawings), installation guide with torque specifications and alignment tolerances, material certificates and Declaration of Performance, DDP (Delivered Duty Paid) delivery to your UK site, single cantilever and double cantilever configurations, and optional EV charging cable management integration.
What you provide: Site survey and setting-out, foundation construction, frame erection and bolt torquing, PV panel installation and electrical works, grid connection and commissioning, and MCS certification (where applicable).
This scope split is clean and proven. You retain full control of the installation, and we deliver a certified, engineered structural product ready for erection.
Ready to specify a solar carport frame kit for your next project? View our solar carport systems
About the Author
Keith Lin is the Director of KLY Solar (KLY Global Ltd), a UK supplier of solar carport structure kits for commercial project teams.
Sources cited in this article:
KLY GLOBAL LTD trading as KLY Solar | Company No. 14169672
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