A solar PV installation is certified on an Electrical Installation Certificate (EIC) because it adds new fixed wiring: the a.c. supply circuit from the board to the inverter and the d.c. array itself. Section 712 of BS 7671:2018+A4:2026 sets the d.c.-side rules the EIC and its schedules must show were met, and BS EN 62446-1 adds a separate PV array test record listing open-circuit voltage, short-circuit current and insulation resistance for every string. MCS certification and the G98 or G99 notification are separate documents with separate jobs. Nothing in Amendment 4 rewrote Section 712, but its new Chapter 57 on batteries and the redrafted Regulation 551.7 change how PV-plus-storage jobs are designed and certified.
- The EIC is the BS 7671 certificate for a PV install. The MCS certificate, the BS EN 62446-1 array test record and the G98/G99 paperwork sit alongside it, and a handover pack without the EIC is incomplete.
- Section 712 treats the d.c. side as live in daylight: Class II construction, d.c. isolation at the inverter, warning labels, and SPDs on the d.c. side where Section 443 calls for them.
- An RCD on the PV supply cable must be Type B unless the inverter provides simple separation or its manufacturer declares it cannot feed smooth d.c. into the installation.
- Amendment 4 (published 15 April 2026; A2+A3 withdrawn 15 October 2026) left Section 712 alone but added Chapter 57 for stationary batteries and treats a battery as a generating set under 551.7.2.1.
- G98 covers up to 16 A per phase in total at the premises, storage included, notified within 28 days of commissioning; anything more is G99, with the SGI-2 and SGI-3 routes for small aggregated systems.
- Plug-in solar up to 800 VA has been lawful since 27 August 2026 under SI 2026/848; it needs no certificate unless you alter the circuit it plugs into.
Which certificate does a solar PV installation need?
An EIC is the model form for a new installation, an addition or an alteration that adds a circuit, and a PV system adds at least one: the dedicated a.c. circuit from the consumer unit to the inverter, which Regulation 712.551.7.2 requires to be connected on the supply side of the overcurrent device for the installation's own circuits. It also introduces the d.c. array, which is fixed wiring and is inspected and tested under Chapter 64 like anything else. A Minor Works Certificate is wrong for the original installation; it is for a later like-for-like inverter swap on the existing circuit, as set out in EICR vs EIC: what's the difference and Minor Works Certificate: when to use it.
| Document | Issued by | What it certifies |
|---|---|---|
| EIC with schedules of inspections and test results | The installing electrician | The a.c. circuit and d.c. array comply with BS 7671:2018+A4:2026 |
| PV array test record to BS EN 62446-1 | The installer or commissioning engineer | String Voc, Isc, insulation resistance, polarity and functional tests |
| MCS certificate | MCS-certified installer via the MCS Installation Database (MID) | Installation to MIS 3002; needed for Smart Export Guarantee payments |
| G98 notification or G99 acceptance | Installer to the DNO | The generator is registered on the network |
| Building Regulations compliance certificate | Competent person scheme or building control | Part P notification in England and Wales |
The EIC describes the extent of the work in plain terms, for example "4 kWp grid-connected PV: ten modules, one string, single-phase inverter in loft, new 16 A a.c. circuit from consumer unit via 20 A RCBO". Supply characteristics, earthing arrangement and main protective conductors are recorded as for any new circuit. Anything you found at the board, such as missing main bonding, goes in the comments on the existing installation under 644.1.2; it is not your job to fix it under this certificate, but it is your job to write it down.
What does Section 712 require on the d.c. side?
Section 712 sits in Part 7, so its regulations add to or modify the general rules rather than replacing them. The points that turn up on the schedule of inspections are these.
Live in daylight. PV modules generate as soon as light falls on them. Regulation 712.410.3 requires the d.c. side to be treated as energised even when it is disconnected from the a.c. side, and automatic disconnection in the Chapter 41 sense is generally impractical on a floating d.c. array, so shock protection on the d.c. side is by double or reinforced insulation (Section 412). In practice that means purpose-made single-core PV cable (commonly H1Z2Z2-K), matched connectors of one make throughout a string, and no exposed d.c. terminals in ordinary enclosures. Mismatched connectors from different manufacturers are a recognised cause of arcing and fire. Never open a d.c. connector under load.
Isolation on both sides. Regulation group 712.537.2 requires means of isolation on the d.c. side and the a.c. side of the inverter. A d.c. switch-disconnector must be rated for the string open-circuit voltage at low temperature and for load-breaking d.c. duty; an a.c. switch relabelled "DC" is not. Many inverters carry an integral d.c. switch that satisfies the requirement; where the inverter is remote from the array, an additional isolator near the modules is usual. The a.c. isolator sits adjacent to the inverter, and a further means of isolation is normally provided at the consumer unit.
Labels. Regulation 514.15.1 requires a warning notice at the origin, the meter position, the consumer unit and the inverter stating that there is an alternative supply, and Section 712 requires "PV system, d.c. live in daylight" type labels at the d.c. isolators and, under 712.537.2.2.5.1, at junction and combiner boxes. Anyone pulling the DNO fuse needs to know the roof cables stay live.
Overcurrent protection and the supply cable. Regulation 712.433.104 sets the design current for the inverter supply cable as the inverter's rated a.c. output current where the manufacturer gives it, otherwise 1.1 times its a.c. current rating. Protective devices must not be impaired by any d.c. component from the inverter or its filters (551.4.3.3.2). If the supply cable runs concealed in a wall at less than 50 mm depth without earthed mechanical protection, 522.6.202 and 522.6.203 bring in the usual additional-protection RCD, and 551.7.1(ii) wants that RCD to disconnect all live conductors including neutral.
SPDs. Regulation 712.443.101 applies the Section 443 risk assessment to the d.c. side: where overvoltage protection is required for the installation, it is required on the d.c. side too. Type 2 devices are the norm. Where the building has a lightning protection system and the BS EN 62305-3 separation distance is not achieved, 712.534.101 and 712.534.102.1 call for Type 1 (or combined Type 1+2) devices, with SPD earthing conductors of at least 6 mm² for Type 2 and 16 mm² for Type 1 back to the main earthing terminal, and 712.534.105 asks you to keep the loop between SPD assemblies as short as possible. The general rules are in SPD requirements, Regulation 443.
Which RCD type does the a.c. side need?
The a.c. circuit from the inverter to the board is a normal final circuit with its own overcurrent device and isolation. The RCD question is the one that catches people out. Regulation 712.531.3.5.12 (712.411.3.2.1.2 in the original 2018 text) says that where an RCD protects the PV supply cable and the inverter does not provide at least simple separation between its d.c. and a.c. sides, the RCD shall be Type B. Type AC and Type A are ruled out because a transformerless inverter can, on a d.c.-side insulation fault, push smooth d.c. residual current into the a.c. side and blind them.
| Inverter construction | RCD on the PV supply cable |
|---|---|
| Transformer (galvanic) isolation between d.c. and a.c. | Any type suited to the load; Type A is the usual floor |
| Transformerless, manufacturer declares no smooth d.c. fault current possible | Type as the manufacturer states, commonly Type A |
| Transformerless, no declaration | Type B |
Most current transformerless string inverters carry the declaration, and NICEIC's July 2024 guidance on the a.c. side confirms that the manufacturer's instructions or galvanic isolation lift the Type B requirement. Keep a copy of the data sheet with the job and write the basis in the remarks: "Inverter make/model; manufacturer declares no smooth d.c. residual current; Type A RCBO fitted". Amendment 4 adds a further point. A new note to Regulation 531.3.3, with Figure A53.2, says RCDs in series must all suit the residual current types expected downstream: Type A must not sit upstream of a Type F or B, and Type AC must not sit upstream of A, F or B, unless the manufacturer specifically declares the arrangement suitable. If you fit a Type B RCBO for an inverter under a Type A front-end RCD, that front end is the problem. RCD types and the single 643.8 test are covered in RCD testing explained.
What goes on the PV array test record?
BS EN 62446-1 (grid-connected PV systems: requirements for system documentation, commissioning tests and inspection) is the standard MCS references, and its Category 1 tests apply to every system regardless of size. Category 2 (I-V curve tracing and infrared thermography) is for larger or more complex arrays and only after Category 1 has passed. The d.c. side is tested with a PV-rated instrument that can handle the string voltage, not a standard installation tester.
| Category 1 test | What it proves | Acceptance |
|---|---|---|
| Continuity of earthing and bonding conductors | Frame earthing and bonding (where fitted) are sound | Low resistance consistent with conductor length |
| Polarity of each string | Nothing is reversed at a connector, combiner or the inverter | Correct throughout |
| Combiner box check | String fuses, SPDs and isolators present and rated | As designed |
| Open-circuit voltage (Voc) per string | Module count and series connections are right | Within the expected range for the module count and cell temperature |
| String current (Isc or operating) | Every module and bypass diode is contributing | Similar across identical strings, consistent with irradiance |
| Insulation resistance of the d.c. array | No leakage from d.c. conductors to earth | See the table below |
| Functional tests | Isolators, inverter start-up, shutdown and loss-of-mains behaviour | As the manufacturer states |
The insulation resistance test voltage and minimum follow the system voltage, as set out in BS EN 62446-1 and summarised by the instrument makers.
| PV system voltage (Voc × 1.25 at STC) | Test voltage | Minimum insulation resistance |
|---|---|---|
| Below 120 V | 250 V d.c. | 0.5 MΩ |
| 120 V to 500 V | 500 V d.c. | 1 MΩ |
| Above 500 V | 1,000 V d.c. | 1 MΩ |
There are two methods: test each pole to earth in turn, or short the positive and negative string conductors together (with a short-circuit switch rated for the string, never by hand) and test the pair to earth. Record which you used, along with irradiance and module temperature at the time of each Voc and Isc reading, because a 10-module string reading 380 V at noon in June and 410 V on a cold bright February morning are both correct. The general principles of the test are in the insulation resistance testing guide.
What goes on the EIC schedules?
The schedule of test results carries the a.c. circuit as a line: cable size and reference method, OCPD type and rating, RCD type and rating where fitted, continuity, insulation resistance at 500 V with the inverter disconnected, polarity, Zs at the a.c. isolator or inverter terminals, and the RCD disconnection time at IΔn. Check Zs against the maximum for the device as in maximum Zs values; on a TN-C-S supply a 20 A Type B RCBO on a short 4 mm² run will be well inside the 1.75 Ω (80 per cent) limit, but a long run to a detached garage inverter on 2.5 mm² may not be. The d.c. array results are referenced in the remarks ("d.c. array tested to BS EN 62446-1, see attached PV array test record, 2 strings, Voc 395 V/397 V, IR greater than 200 MΩ at 1,000 V") rather than forced into columns designed for a.c. circuits. Column-by-column help is in how to fill in a schedule of test results.
On the schedule of inspections, record that you checked d.c. cable support on the roof and through the building, connector matching, the d.c. and a.c. isolators and their labels, SPD presence and indicator status, inverter ventilation and clearances, and the fixing of any earthing conductor to the array frame. On the A4:2026 model EIC the departures box at Section A and the comments on the existing installation are where you note anything outside the norm, such as a design to a manufacturer's declaration rather than a Type B RCD. The current form is walked through in the EIC explained guide.
How does the MCS certificate relate to the EIC?
The Microgeneration Certification Scheme is a quality scheme for installers and products, not a wiring regulation. An MCS-certified installer works to MIS 3002, the solar PV installation standard. The current issue, MIS 3002 V6.0, became mandatory on 18 June 2026 and applies to systems up to 50 kWp d.c.; the March 2026 update tightened clause 5.5.5 so that where no MCS 012-certified mounting system exists the installer must hold evidence of structural and wind-loading calculations, fire performance and weather-tightness for the specific mounting system used. Clause 5.9.4 requires a suitably competent person to confirm a pitched roof can carry the loads, and 5.9.6 and 5.9.13(h) call for a structural engineer on unusual roofs (post-construction modifications, pitches under 30 degrees, dormers, valleys, parapets) and on any ballasted system.
The installer registers the job on the MCS Installation Database no later than 10 working days after commissioning and raises the MCS certificate, which must go in the customer's handover pack along with the EIC, the array test record, the G98 or G99 paperwork, a schematic, a performance estimate and the operation and maintenance information. Suppliers with 150,000 or more customers must offer a Smart Export Guarantee tariff under Ofgem's rules, and they require MCS (or equivalent) certification before paying for export, which is why customers call it "the solar certificate".
MCS does not replace BS 7671 certification: an MCS certificate without an EIC behind it is incomplete. An electrician who is not MCS-certified can lawfully install PV and issue an EIC, and the installation is no less safe for it, but the customer will struggle to get export payments through most suppliers.
What DNO notification does PV need?
Generation connected in parallel with the public network is notified under the ENA engineering recommendations. The figures below are as Voltimum set them out for installers on 29 September 2026.
| Route | Capacity at the premises | Process |
|---|---|---|
| G98 | Up to 16 A per phase in total (3.68 kW single-phase, 11.04 kW three-phase) | Install, commission, then notify the DNO within 28 days |
| G99 SGI-1 | Units up to 16 A each and 16 A in total | Notify after commissioning on Form A3-3 |
| G99 SGI-2 | Units up to 16 A each, up to 32 A in total | Apply first on Form A1-2; DNO may impose a 16 A export limit |
| G99 SGI-3 | Units up to 32 A each, up to 60 A in total | Apply first on Form A1-2; DNO may impose a 32 A export limit |
| G99 standard (Type A, above 16 A to under 1 MW) | Larger systems | Apply first; assessment and connection offer, then commission and submit compliance forms |
Two things trip installers up. First, the 16 A threshold applies to everything at the premises: an existing 3.68 kW inverter plus a new 3.68 kW battery inverter is 32 A and is a G99 job, and registered capacity is the lesser of the inverter rating and the energy source rating. Second, a G100 export limitation scheme controls export with a sensor and inverter control, but it is not a separate application and does not by itself qualify a system for the fast track; the fast track (Form A1-2 for fully type-tested solar and storage) is where the DNO's confirmation is due within 10 days rather than 45.
Did Amendment 4 change anything for PV work?
Not Section 712 itself. SELECT's "Amendment 4: What's New" and BEAMA's April 2026 summary list no Section 712 changes. What A4 does change for anyone fitting PV with storage:
- Chapter 57, Stationary Secondary Batteries, is new, with more than 18 regulations covering battery selection, power conversion equipment, the energy management system, earthing, shock protection, d.c.-side fault protection, isolation, and identification and notices. Regulation 570.6.7.203 requires batteries in dwellings to be sited with regard to the manufacturer's instructions and PAS 63100, and requires a Type B RCD unless the power conversion equipment provides simple a.c./d.c. separation, a transformer provides simple separation between it and the RCD, or the manufacturer states that no Type B RCD is required.
- Regulation 551.7.2.1 now treats a stationary battery as a generating set rather than a load and requires it to be connected on the supply side of all protective devices for the installation's circuits. 551.7.1 gains indent (c), a suitable protective device where energy flow is bidirectional, and indent (d), which prohibits connecting a source to the load side of an RCD in certain conditions.
- Regulation 551.7.2.2 gives four options for rating switchgear that carries a generator in parallel with the supply; BEAMA's example is a 100 A supply plus a 16 A generator needing a consumer unit rated at 116 A. Check the board's rating before landing a second inverter in it.
- Regulation 530.3.201, consolidated from A3:2024, requires you to account for unidirectional versus bidirectional protective devices; an RCBO marked line/load or with arrows is unidirectional and must not carry reverse power from an inverter.
PAS 63100:2024, in force since 31 March 2024, is the fire-safety document A4 points to: batteries should preferably go outside the dwelling (garage, outbuilding, external enclosure), and where they must be inside they are kept out of habitable rooms and escape routes, with fire detection in the battery location and a label at the consumer unit stating that a battery system, or PV and battery, is present. The EV charger Section 722 guide covers the parallel changes for bidirectional charging. The amendment as a whole is summarised in BS 7671 Amendment 4: what changes.
What about plug-in solar?
Plug-in (balcony) solar became lawful in Great Britain on 27 August 2026 under SI 2026/848, which amends the Plugs and Sockets etc. (Safety) Regulations 1994 and ESQCR 2002 so that a "plug-in microgenerator" to the DESNZ Plug-in Solar Device Interim Product Specification v2.0 (published 16 July 2026) can connect through a standard socket. The specification limits the device to 800 VA and 3.5 A at the plug with no more than 2,000 W of modules, requires a G98 type-tested inverter registered on the ENA type-test register with disconnection within 100 ms of loss of mains, a moulded BS 1363-1 plug with a 5 A or smaller fuse, one device per socket circuit, no extension leads or adaptors, and no connection to any battery storage. DNO notification is mandatory and the product must carry a QR code to the registration guidance.
For you the position is simple. A householder plugging one in makes no change to the fixed wiring, so no certificate arises. The specification tells the user to involve an electrician where the circuit needs altering, where the board has older fuse protection without RCBOs, or where the consumer unit is unlabelled or of unknown condition. Replacing the circuit's MCB with an RCBO so the device has a modern RCD in front of it is a Minor Works Certificate job. On an EICR, a plug-in device on a socket is not an installation defect, but note its presence in the observations, because the next person isolating the board needs to know a generator can be hanging off a socket, and check the upstream RCD type against the device's declared d.c. residual current (the specification caps it at 5 mA).
Is solar PV notifiable under Part P?
Yes. In England and Wales, adding a new circuit in a dwelling is notifiable under Part P of the Building Regulations, through your competent person scheme or building control before the work starts, as explained in Part P notification explained. In Wales, outdoor and kitchen work is also notifiable. Roof-mounted arrays may also need a Part A structural check; for MCS work that is what MIS 3002 clauses 5.9.4 to 5.9.13 are formalising. Planning permission is normally not needed under permitted development, except for listed buildings, and in conservation areas where panels face a highway.
How Certio helps
Certio produces the EICR, EIC, Minor Works certificate and PAT records on the BS 7671 model forms and turns them into branded PDFs. Photograph the consumer unit and the circuit schedule drafts itself; point the phone camera at a Megger MFT-X1 and the reading goes straight into the schedule of test results, or dictate it while your hands stay on the probes. Suggested observation wording with the regulation reference is there for you to check and confirm. The judgement stays yours; the typing goes. Starter is £4.99 a month, charged when you sign up.
Sources
BS 7671:2018+A4:2026 Section 712, Chapter 57 and Regulations 551.7, 531.3.3, 530.3.201 (published 15 April 2026; A2:2022+A3:2024 withdrawn 15 October 2026); SELECT, "2026 Amendment 4: What's New"; BEAMA/EDA, "18th Edition Amendment 4" presentation, April 2026; NICEIC, "Solar PV part three" (a.c. side), 16 July 2024; Voltimum, "Electrical installations and solar", 10 July 2023, and "G98 vs G99: grid connection applications for installers", 29 September 2026; BS EN 62446-1 Category 1 tests and insulation resistance table (as summarised by Fluke and Hioki); MCS, "MCS publishes update to MIS 3002", 18 March 2026, and "Registering your MCS installation on the MID"; PBC Today, "What MIS 3002 actually requires", 24 September 2026; SI 2026/848 and the DESNZ Plug-in Solar Device Interim Product Specification v2.0, July 2026; PAS 63100:2024; IET GN3 10th Edition; Electrical Safety First.