A solar PV installation is certified on an Electrical Installation Certificate (EIC) because it adds a new circuit to the installation, and Section 712 of BS 7671:2018+A4:2026 sets the specific requirements for the d.c. side that the EIC and its schedules must show have been met. In addition to the EIC, BS EN 62446-1 requires a PV array test record listing open-circuit voltage, short-circuit current and insulation resistance for each string. Where the installer is MCS-registered, an MCS certificate is issued as well, but it is a scheme document and not a BS 7671 certificate. Systems up to 16 A per phase are notified to the DNO under G98 within 28 days; larger ones need G99 approval before connection.
- The EIC is the BS 7671 certificate for a PV install; the MCS certificate and the G98/G99 notification are separate documents with separate purposes.
- Section 712 treats the d.c. side as live whenever there is daylight: double or reinforced insulation, d.c. isolation at the inverter, and "PV system" warning labels at the origin, meter and isolators.
- If an RCD protects the a.c. circuit and the inverter has no simple separation, it must be Type B unless the manufacturer declares the inverter cannot feed smooth d.c.
- The PV array test record to BS EN 62446-1 carries Voc, Isc, insulation resistance and irradiance per string; the schedule of test results carries the a.c. circuit.
- Battery storage is a distinct piece of work with its own certificate, and BS 7671 Amendment 4 adds a chapter on stationary secondary batteries.
Which certificate does a solar PV installation need?
An Electrical Installation Certificate (EIC) is the BS 7671 form for a new installation or a new circuit, and a PV system adds at least one: the a.c. supply circuit from the consumer unit to the inverter. It also introduces the d.c. array, which is part of the fixed installation and must be inspected and tested under Chapter 64. A Minor Works Certificate is not appropriate for the original installation, only for a later like-for-like inverter swap on the existing circuit; see EICR vs EIC: What's the Difference? (and Minor Works).
| Document | Issued by | What it certifies |
|---|---|---|
| EIC with schedules | The installing electrician | The a.c. circuit and d.c. array comply with BS 7671 |
| PV array test record | The installer or commissioning engineer | String Voc, Isc, IR, polarity and functional tests to BS EN 62446-1 |
| MCS certificate | MCS-registered installer via the MCS database | Installation to the MCS standard (MIS 3002), needed for Smart Export Guarantee payments |
| G98/G99 notification or acceptance | Installer to the DNO | The generator is registered on the network |
| Part P compliance certificate | Competent person scheme | Building Regulations notification (England and Wales) |
What does Section 712 require on the d.c. side?
Section 712 covers solar photovoltaic power supply systems and is in Part 7 of BS 7671, so its rules add to or modify the general requirements.
Live in daylight
PV modules generate as soon as light falls on them, so the string cables and the d.c. side of the inverter cannot be made dead by switching. Section 712 requires the d.c. side to be treated as live during installation and inspection; never disconnect a d.c. plug under load.
Double or reinforced insulation
The d.c. side is wired so as to give Class II (double or reinforced) insulation, so that a single fault to earth does not create a shock or fire risk. In practice that means purpose-made single-core PV cable (commonly H1Z2Z2-K), connectors of one make throughout, and no exposed d.c. terminals in ordinary enclosures. Mismatched connectors from different manufacturers on one string are a recognised fire cause.
d.c. isolation
A d.c. switch-disconnector rated for the string voltage and load-breaking duty must be installed on the d.c. side of the inverter. Many inverters have an integral d.c. switch that meets this; where the inverter is remote from the modules, an additional isolator near the array is common. The isolator must break both poles and be rated for d.c., not an a.c. switch relabelled.
Labelling
Section 712 requires warning labels stating that the installation contains a PV system and that the d.c. side is live in daylight, placed at the origin, the meter position, the isolators and the inverter, so that anyone isolating the a.c. supply knows the d.c. cables remain live. A label showing the presence of an alternative supply is also required at the origin.
a.c. side and RCD type
The a.c. circuit from the inverter to the consumer unit is a normal final circuit with its own overcurrent protection and a.c. isolator. Section 712 states that where an RCD is used on the a.c. side and the inverter does not provide at least simple separation between d.c. and a.c., the RCD must be Type B, unless the inverter cannot feed smooth d.c. fault currents into the installation, which most current transformerless inverters declare in their data sheets. Record the RCD type and the basis for it in the remarks; RCD types are explained in RCD Testing Explained: Types, Test Currents and Trip Times.
What goes on the PV array test record?
BS EN 62446-1 (Photovoltaic systems: requirements for testing, documentation and maintenance) sets out the minimum tests for a grid-connected PV system and is the standard MCS references. The tests use a PV-rated instrument, never a standard MFT on the d.c. side.
| Test | What it proves | Typical acceptance |
|---|---|---|
| Continuity of earthing and bonding conductors | Frame earthing (where fitted) is sound | Low resistance, consistent with conductor length |
| Polarity | Each string is connected the right way round | Correct at every connector and the inverter |
| Open-circuit voltage (Voc) per string | Module count and connections are correct | Within the expected range for the module count and temperature |
| Short-circuit current (Isc) per string | Strings are producing, no open modules or bypass diode faults | Similar across identical strings, consistent with irradiance |
| Insulation resistance of the d.c. array | No leakage from d.c. conductors to earth | 500 V test, min 1 MΩ for systems 120 V to 500 V; 1,000 V test, min 1 MΩ above 500 V; 250 V test, min 0.5 MΩ below 120 V |
| Functional tests | Isolators, inverter start-up, shutdown and anti-islanding | Operates as the manufacturer states |
| Irradiance and module temperature | Puts Voc and Isc in context | Recorded at the time of each test |
Insulation resistance is measured between the shorted string conductors and earth, or between each pole and earth in turn, with an instrument rated for the string voltage; note the method used. The general principles are in Insulation Resistance Testing Guide: Voltages, Minimums, Method.
What goes on the EIC and the schedule of test results?
The EIC describes the extent of the work ("4 kWp grid-connected PV system: 10 modules, one string, single-phase inverter in loft, new 16 A a.c. circuit from consumer unit") and records the supply characteristics, earthing arrangement and main protective conductors as for any new circuit. Anything found at the consumer unit, such as missing main bonding, goes in the comments on the existing installation.
The schedule of test results carries the a.c. circuit as a line: cable size, OCPD type and rating, RCD type where fitted, continuity, insulation resistance at 500 V, polarity, Zs at the a.c. isolator or inverter terminals, and RCD trip times. Zs is checked against the maximum for the device as in Maximum Zs Values BS 7671: Tables, 80% Rule and Ze. 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") rather than forced into columns designed for a.c. circuits. Line-by-line guidance is in Schedule of Test Results: How to Fill In Every Column. The schedule of inspections should show that labelling, d.c. isolation, cable support on the roof and through the building, connector matching and inverter ventilation were checked.
How does the MCS certificate relate to the EIC?
The Microgeneration Certification Scheme (MCS) is a quality scheme for installers and products, not a wiring regulation. An MCS-registered installer works to the MCS installation standard for PV (MIS 3002) and issues an MCS certificate through the MCS Installation Database. Energy suppliers require that certificate before paying under the Smart Export Guarantee, and it is what customers mean by "the solar certificate".
The MCS handover pack is expected to include the EIC, the PV array test record, the G98 or G99 paperwork, a performance estimate, a schematic and the operation and maintenance information. MCS does not replace BS 7671 certification; an MCS certificate without an EIC behind it is incomplete. An electrician who is not MCS-registered can lawfully install PV and issue an EIC, but the customer will not be able to claim export payments through most suppliers.
What DNO notification does PV need?
Generation connected to the public network must be notified to the Distribution Network Operator under the Energy Networks Association engineering recommendations:
| Recommendation | System size | Process |
|---|---|---|
| G98 | Up to 16 A per phase (3.68 kW single-phase, 11.04 kW three-phase) | Install and connect, then notify the DNO within 28 days |
| G99 | Above 16 A per phase | Apply to the DNO before installation; approval may take weeks and may impose export limits |
A domestic system with a 3.6 kW inverter is sized to stay within G98. If a battery inverter is added later the combined capacity counts, which can push the installation into G99.
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 via building control before work starts; see Part P Notification Explained: What Electrical Work Is Notifiable. Roof-mounted arrays may also need a Part A structural assessment. Planning permission is normally not needed under permitted development, except for listed buildings and conservation areas.
What about battery storage?
Battery energy storage systems (BESS) are a separate piece of electrical work. A battery or hybrid inverter needs its own protection and isolation, generator labelling, a review of the RCD type and often a new circuit, so it needs an EIC or, for a small addition to an existing hybrid circuit, a Minor Works Certificate. The IET Code of Practice for Electrical Energy Storage Systems is the accepted installation guide.
BS 7671:2018+A4:2026, published 15 April 2026, introduces a new chapter on stationary secondary batteries covering the topics installers have been asking about: where batteries may be located, protection and isolation of the battery circuit, ventilation and thermal considerations, and labelling. A2 is withdrawn on 15 October 2026, after which designs must follow A4. The overall changes are summarised in BS 7671 Amendment 4 (2026): What Changes for Electricians.
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 free for 7 days, then £5 a month.