Earthing and Grounding Solar Systems: BS 7671, PME and Lightning Protection (UK 2026)

Earthing (called grounding in some countries) is a critical safety system that provides a low-resistance path for fault currents to flow safely to ground. In a solar installation, proper earthing protects against electric shock, fire, and equipment damage by ensuring that any fault condition – such as damaged insulation or a lightning strike – results in current flowing harmlessly to earth rather than through people or causing fires.

A properly earthed solar system connects all exposed metal parts (panel frames, mounting rails, inverter casings) to the main earthing terminal of the property, which connects to the ground via an earth electrode. This creates an equipotential zone where touching any metal part during a fault won’t result in dangerous voltage differences. UK regulations require all solar installations to be properly earthed in accordance with BS 7671 (the IET Wiring Regulations).

This guide explains why earthing matters, what the UK regulations require, how solar systems are earthed in practice, common configurations including the PME considerations that catch many homeowners by surprise, and what to check to ensure your system is properly protected.

Earthing at a Glance

Why Earthing Matters

Protection Against Electric Shock

For the broader context on solar electrical safety – DC voltages, what’s safe to touch, and emergency response – see our guide on can solar panels electrocute you.

Fire Prevention

Sustained DC arcs are one of the few realistic fire-ignition pathways on a solar installation. Modern inverters increasingly include arc-fault detection circuitry as a backup to good earthing – see our arc fault detection guide for the detail.

Equipment Protection

UK Regulatory Framework

Key Standards

BS 7671 is published jointly by the Institution of Engineering and Technology and the British Standards Institution, and although it is technically non-statutory it is referenced in numerous UK regulations and treated as the authoritative method of compliant electrical installation. The IET’s BS 7671 earthing and bonding FAQs are the most accessible reference for the topic.

BS 7671 Requirements

Section 712 (Solar PV)

Section 712 sits within a broader regulatory stack covered by Part P of the Building Regulations – which makes solar PV electrical work notifiable and forces it through a competent-person scheme. Our Part P guide covers the certification side in detail.

Who’s Responsible

Types of Earthing Systems

UK Earthing Arrangements

TN-S System

TN-C-S (PME) System

TT System

Components of Solar System Earthing

What Gets Earthed

For a refresher on what each of these components does in the wider system – see our breakdown of solar panel system components.

Panel Frame Earthing

Mounting System Earthing

Inverter Earthing

DC Side Earthing

Functional vs Protective Earthing

Grounded vs Ungrounded DC Systems

Transformerless Inverters

Microinverter and module-level systems push the DC/AC boundary up to the panel itself, eliminating the high-voltage DC string entirely. From an earthing perspective this simplifies the picture – see our guide to microinverters for residential solar for the full trade-offs.

Insulation Monitoring

AC Side Earthing

Standard Requirements

Consumer Unit Connection

RCD Type Requirements

Surge Protection and Earthing

Why SPDs Need Good Earthing

SPD Earthing Requirements

Lightning Protection

For severe-weather risks more broadly – including how to react after a lightning strike or major storm event – see our storm damage and solar panels guide.

Equipotential Bonding

What It Means

Main Bonding

Supplementary Bonding

Solar-Specific Bonding

Testing and Verification

Tests Required

Continuity Testing

Earth Fault Loop Impedance

Documentation

Common Earthing Issues

Installation Problems

Anodised Frame Issues

Degradation Over Time

PME (TN-C-S) Considerations

Earth Electrodes

When Required

Types of Earth Electrode

Earth Electrode Resistance

Installer Responsibilities

Design Requirements

Installation Requirements

Testing and Certification

What Homeowners Should Know

Signs of Proper Earthing

Warning Signs

If you see signs of an earthing fault – particularly an inverter throwing repeated insulation-resistance errors – our solar panel fault-finding guide walks through the safe diagnostic sequence before you call out an electrician.

Maintenance Considerations

Frequently Asked Questions

Basic Questions

Technical Questions

Summary

Earthing is a fundamental safety system that protects you from electric shock and your home from fire. Every solar installation must be properly earthed in accordance with BS 7671, with all exposed metal parts – panel frames, mounting rails, inverter casing – connected to the main earthing terminal of your property. This creates an equipotential zone where fault currents flow safely to earth rather than through people.

Your installer is responsible for designing, installing, and testing the earthing system. This includes ensuring all metal parts are bonded together, conductors are correctly sized, and connections are secure. All test results should be recorded on your Electrical Installation Certificate, including earth fault loop impedance values that prove the system will operate safely.

Most UK solar installations use transformerless inverters with floating (ungrounded) DC systems. The DC conductors themselves aren’t connected to earth, but all metalwork is. The inverter monitors insulation resistance on the DC side and will shut down if it detects a fault. This approach provides safety while maximising efficiency.

As a homeowner, you can visually check that green/yellow earth wires are visible and connections appear secure, but proper testing requires a qualified electrician. Any concerns – particularly tingling sensations from metal parts – should be investigated immediately. Keep your certificates safe; they document that your system was properly installed and tested.