A solar PV installation method statement has to satisfy three regulatory regimes at once: work at height (WAHR 2005), electrical safety (Electricity at Work Regs 1989 / BS 7671 with the IET Code of Practice for Grid-Connected Solar PV Systems), and — where MCS-certified for the Smart Export Guarantee or for finance — the MCS 005 installer standard and MCS 020 standard for the system itself. The document must sequence the install end-to-end (scaffold / fall-arrest, roof penetration, rail installation, panel placement, DC string, isolator, inverter, AC tie-in, commissioning) and address the two emerging high-consequence risks: DC arc faults and lithium-ion battery storage where in scope.
WAHR 2005 reg 6 applies to every minute of work above the eaves. The method statement names the access method (scaffold with edge protection is the default; MEWP for steep / fragile roofs; harness-and-anchor for short-duration access where scaffold is not reasonably practicable). Fragile-roof work (cement sheet, fibreglass rooflights) triggers HSG33 specifically.
The electrical work falls under EAWR 1989 with BS 7671 18th Edition (Amendment 2 or current) as the recognised standard. The IET Code of Practice for Grid-Connected Solar PV Systems is the de facto reference for DC system design, isolator specification, string sizing, surge protection and earthing. For MCS-certified installations, MCS 005 (installer standard) and MCS 020 (system standard) set the additional requirements the DNO and the SEG-licensee will expect to see.
DC strings on a rooftop PV system can exceed 600 V even at modest scale and cannot be 'switched off' while the sun is shining — disconnecting a live DC circuit under load creates a sustained arc. The method statement must name: the DC isolator(s) (located close to the array, accessible to fire service, IP-rated, labelled), the AC isolator (accessible at ground level, labelled, lockable), the surge protection device (SPD type 1 or 2 to BS EN 61643-11), the earthing arrangement (equipotential bonding of the rails to the building MET), and the sequence-of-isolation procedure for commissioning, fault-finding and emergency.
The fire service expects a dual-isolator layout with clear labelling on the consumer unit cover and a system diagram displayed at the inverter location. A document that conflates AC and DC isolation, or omits the SPD, is a routine reason for the MCS auditor to fail the install.
Where a lithium-ion battery (BESS) is added — increasingly the default for residential SEG-optimised systems — the method statement extends to PAS 63100 (battery storage installation in dwellings) and to MCS 029 / IET Code of Practice for Electrical Energy Storage Systems. The document names the battery location (typically not loft, ideally garage or external wall-mount with thermal segregation from habitable rooms), the ventilation, the fire-detection arrangement, the EPO (emergency power-off), and the manufacturer-specific commissioning checklist.
For commercial scale (above ~50 kWh) the document also references the local fire-and-rescue service consultation under the Regulatory Reform (Fire Safety) Order 2005.
MCS auditors, principal contractors and DNO inspectors read in this order: access / scaffold method and WAHR hierarchy justification; fragile-roof assessment (HSG33); structural calculation for the array load on the roof (especially retrofits — the SAP / surveyor calculation must accompany the method statement); DC isolator location, type, labelling; SPD specification; earthing arrangement; AC tie-in and G98 / G99 application reference; commissioning and handover certificates; battery section where in scope.
A method statement that does not address fragile-roof risk, omits the SPD or conflates AC and DC isolation will be rejected by a competent reviewer before the rest of the document is read.
The numbered sections a reviewer expects to see, in order.
Address, system size in kWp, panel make / model / count, inverter make / model, battery if in scope (capacity, chemistry), G98 or G99 reference.
Scaffold / MEWP / harness — with WAHR reg 6 hierarchy justification; fragile-roof assessment under HSG33.
Reference to the structural calculation / surveyor's certification for the array dead load and uplift on the roof structure.
Fixing pattern, flashing detail, manufacturer-specific kit, NHBC / LABC compliance where new-build.
String sizing, DC isolator type / location / labelling, SPD type, earthing and equipotential bonding to the MET.
Inverter location (ventilation, ambient temperature), AC isolator, MCB rating, RCD where required, consumer unit modification.
PAS 63100 / MCS 029 compliance, location, ventilation, fire detection, EPO, manufacturer commissioning checklist.
Insulation resistance, polarity, open-circuit voltage and short-circuit current per string, AC voltage and earth-loop impedance, inverter G98 / G99 commissioning.
Electrical installation certificate to BS 7671, MCS certificate, system diagram, DNO notification (G98 simple, G99 formal), user manual.
Sequence-of-isolation for fault, fire service access, EPO procedure, labelling on consumer unit cover.
Why a method statement gets sent back — these are the patterns we see most often.
The legal framework this method statement operates inside. Links go to the official source.
SI 2005/735
The hierarchy of control for work at height — applies for the duration of the rooftop install.
SI 1989/635
Statutory framework for electrical work; BS 7671 is the de facto means of compliance.
BS 7671
The recognised standard for electrical installation work in the UK.
IET CoP
The de facto reference for DC string design, isolation, SPD and earthing for PV systems.
HSE HSG33
The standard reference for roof access and fragile-roof work.
ENA EREC G98 / G99
DNO connection rules for embedded generation; G98 for ≤16 A per phase, G99 above.
PAS 63100
Standard for residential battery storage installation — location, fire safety, EPO.
Legally no, but the homeowner / commercial client cannot claim the Smart Export Guarantee or most finance / grant routes without an MCS-certified install and MCS 005 / MCS 020 compliance. In practice all but the most niche off-grid installs are MCS-certified, and the method statement is written to satisfy the MCS auditor as well as the regulator.
Via the DC isolator(s) located close to the array — never by disconnecting a connector under load. The IET Code of Practice for Grid-Connected Solar PV requires the DC isolator to be of the correct type, rated for the open-circuit voltage and short-circuit current, accessible and clearly labelled. Disconnecting connectors under load creates a sustained arc that has caused multiple roof fires.
Yes, where a BESS is in scope. The document extends to PAS 63100 for residential, MCS 029 for installer competence, and the IET Code of Practice for Electrical Energy Storage Systems. Battery location, ventilation, fire detection and the emergency power-off are all named.
G98 is the simplified notification process for embedded generation up to 16 A per phase (around 3.68 kW single-phase, 11 kW three-phase); G99 is the formal application for anything above. The method statement names which the install falls under and references the application / commissioning notification to the DNO.
A competent electrician who is BS 7671-qualified and registered with a recognised competent-person scheme (NICEIC, NAPIT, ELECSA, Stroma) for solar PV. The MCS installer must additionally hold MCS 005 installer competence.
Trade-specific RAMS guidance for the contractors who typically produce this method statement.
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Final RAMS must be reviewed and approved by a competent person before use.