Summary

Building Regulations Part P (Electrical Safety — Dwellings) requires that certain electrical work in domestic premises is either carried out by a registered competent person (who self-certifies) or is subject to a building control application. Solar PV installation involves the addition of a new circuit from the AC side of the inverter to the consumer unit, which is notifiable work under Part P.

For solar PV installers, the practical message is: if you are registered with an approved Competent Persons Scheme, you can self-certify the electrical work as part of the MCS commissioning process. If you are not registered, you need a building control application — which costs money, takes time, and involves a building control officer inspecting the work.

MCS certification and Part P registration are separate. Being MCS-certified does not automatically make you Part P registered; you must hold both to self-certify a solar PV installation.

Key Facts

  • Part P (Building Regulations 2010, Part P) — Electrical Safety — Dwellings; applies in England; Wales has equivalent regulations; Scotland has different building standards
  • Notifiable work — electrical work that must be either self-certified (competent person) or building-controlled; solar PV AC circuit addition to a consumer unit is notifiable
  • Competent Persons Scheme (CPS) — a government-approved scheme under which registered tradespeople can certify their own work as compliant with building regulations; approved schemes include NICEIC, NAPIT, Stroma, ELECSA
  • Self-certification — the registered installer issues an EIC, signs it, and the scheme notifies building control; no building control officer inspects the work
  • EIC (Electrical Installation Certificate) — the certificate issued for new electrical circuits; required for all notifiable solar PV installations
  • Building control application — if the installer is not CPS-registered, a full or limited plans application must be made to local authority building control (LABC) before work starts; a building control officer will inspect
  • Scheme fees — annual CPS registration fees typically £300–£700/year depending on the scheme and scope
  • Part P scope — Part P applies to all fixed electrical installations in or associated with a dwelling; solar PV is included because the inverter AC output connects to the dwelling's electrical installation
  • Non-domestic — Part P does not apply to commercial or industrial premises; commercial solar PV installations are governed by BS 7671 but are self-certified differently
  • Solar PV DC wiring — the DC wiring (panels to inverter) is not separately notifiable under Part P as it is extra-low voltage PV string wiring, but the overall installation including the DC side must comply with BS 7671 and MCS technical requirements
  • MCS and Part P independence — holding MCS certification does not automatically include Part P electrical registration; these are separate accreditations, often held through the same body (NAPIT, NICEIC) but assessed separately

Quick Reference Table: Part P Compliance Routes for Solar PV

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Installer Status Compliance Route Process
MCS-certified + CPS-registered (Part P) Self-certification Install; issue EIC; CPS notifies building control; EIC to customer
MCS-certified only (no Part P) Building control application Apply to LABC before works; LABC inspects; completion certificate issued by LABC
Subcontracting electrical work Use a Part P registered electrical subcontractor Subcontractor issues EIC; their CPS notifies building control
Existing installation work only (no new circuit) May not be notifiable Replacing panels on existing circuits is generally not notifiable; adding new circuit always is

Detailed Guidance

What Part P Requires for Solar PV

Solar PV installation work that is notifiable under Part P includes:

  • Installing the consumer unit connection (the AC connection from the inverter to the consumer unit)
  • Installing a new dedicated AC circuit for the solar inverter
  • Adding a new generation meter or export meter

The DC wiring (panels to combiner box to inverter) is not separately notifiable under Part P but must comply with BS 7671 Chapters 4, 5, and 7 (particularly Section 712: photovoltaic power supply systems).

What Part P does not cover:

  • Roofing and panel mounting (this is building regulations Part A — structure — if structural changes are made; Part C — moisture — for roof penetrations)
  • Scaffolding
  • The planning permission question (separate from building regulations)

Self-Certification Process

Where the installer holds both MCS certification and CPS registration:

Step 1: Complete the installation Install the solar PV system in compliance with MCS 012 technical requirements, BS 7671 (Chapter 712 and relevant sections), and the Part P requirements for the electrical installation.

Step 2: Test and commission Test the electrical installation:

  • Insulation resistance (PV string circuits and AC circuits)
  • Continuity and polarity
  • Earth loop impedance at the consumer unit connection
  • RCD operation (if an RCD is added for the generation circuit)
  • Functional test: system generating and exporting

Step 3: Issue the EIC Complete the Electrical Installation Certificate for the new circuit. The EIC must include:

  • Description of the installation (new generation circuit)
  • Consumer unit details
  • Protective device: RCBO/MCB rating and type
  • Earth loop impedance values
  • Insulation resistance values
  • RCD test results (if applicable)
  • Declaration that the work complies with BS 7671

Step 4: CPS notification Log the job in the Competent Persons Scheme portal and submit the notification. The CPS notifies the local authority building control on the installer's behalf. This triggers the issuance of a building regulations compliance certificate (completion certificate) from the LABC, which is posted to the homeowner.

Step 5: Handover documentation Provide the customer with:

Building Control Application Route

Where the installer is not CPS-registered:

Before works commence: Submit a full plans application to the local authority building control (LABC) or an approved inspector. The application includes:

  • Description of the proposed electrical work
  • Plans showing the proposed installation route and consumer unit connections
  • Building control application fee (typically £200–£400 for a domestic application)

During works: The building control officer may attend site to inspect the work. Alternatively, a completion inspection is arranged after the work is finished.

After completion: The LABC issues a completion certificate confirming compliance with building regulations. This is the equivalent of the CPS-issued completion certificate.

Implications: The building control route adds cost (application fee + potential inspection) and time (application processing may take 1–3 weeks). It also involves a third party verifying the work, which can create delays if the officer requests changes. For commercial installers doing any volume of domestic solar PV work, CPS registration is strongly recommended.

Obtaining Part P Registration

For an existing MCS-certified solar PV installer without Part P registration:

The main approved CPS schemes for electrical work are NICEIC and NAPIT. Many solar installers already use NAPIT for MCS; NAPIT also offers Part P electrical registration as a separate (or bundled) service.

The assessment for Part P registration involves:

  • Evidence of electrical qualifications (e.g., City & Guilds 2382 (18th Edition wiring regulations) + either City & Guilds 2357 or 2391 inspection and testing)
  • Witnessed assessment of electrical work quality
  • Annual fee and audits

For an MCS-certified installer with solar PV qualifications who also holds an IEE/C&G electrical qualification, adding Part P registration is typically a straightforward assessment process.

Wales, Scotland, and Northern Ireland

Wales: Wales has its own building regulations (Building Regulations 2010 (Wales)) with a Part P equivalent. The Competent Persons Scheme route applies similarly.

Scotland: Scotland has Building Standards (Technical Handbooks, not Parts A–P). Electrical installations in Scotland must comply with Building Standards System and BS 7671, but the Part P CPS framework does not apply. Electrical work in Scotland is self-certified by the installer using an EIC; building control notification may be required for notifiable works under the Scottish system.

Northern Ireland: Northern Ireland has its own Building Regulations and Competent Persons Scheme arrangements. Confirm locally.

Frequently Asked Questions

If I'm replacing old solar panels (like-for-like), is that notifiable under Part P?

Replacing panels on an existing generation circuit with like-for-like panels, without modifying the circuit or consumer unit connection, is generally not notifiable under Part P. However, if you replace the inverter (which may require reconnecting to the consumer unit) or add a new circuit, that work is notifiable. Check the Competent Persons Scheme guidance if uncertain.

Does solar PV on a commercial property need Part P certification?

No. Part P applies only to domestic premises (dwellings). Solar PV on a commercial or industrial roof is governed by BS 7671 and MCS (for SEG eligibility) but not by Part P. Building Regulations may apply for structural changes (Part A), and planning permission may be required.

What if I'm a roofer installing the panels but not the electrical work — do I need Part P?

The panel mounting and DC wiring is not separately notifiable under Part P. The notifiable work is the AC connection to the consumer unit. If you are only doing the mechanical and DC side, and a registered electrician is doing the AC connection, only the electrician needs to be Part P registered. Ensure there is a clear demarcation agreed in writing.

Regulations & Standards