BS 7671 Amendment 4: Solar PV Installer Requirements

Solar PV installers are directly impacted by Amendment 4 in two areas: the updated Chapter 72 (Solar Photovoltaic Power Supply Systems) and the new Chapter 57 (Battery Storage Installations). Since the majority of new solar installations now include battery storage, solar installers must be competent in both chapters.

Chapter 72 receives targeted updates in Amendment 4 rather than a complete rewrite. The key changes affect DC arc fault protection, string monitoring, and the interaction with battery storage systems. DC arc fault detection devices (AFDDs) are now recommended for PV string circuits in Amendment 4, following incidents where DC arc faults in string wiring caused roof fires. While not yet mandatory, the recommendation is strong and MCS is expected to adopt it as a requirement in its standards.

The competence crossover between Chapter 72 and Chapter 57 is the most significant change for solar installers. Previously, a solar installer could install PV panels and an inverter without needing detailed knowledge of battery systems — the battery was often installed by a separate specialist. Amendment 4 recognises that solar-plus-battery is now a single system and requires that the person designing the installation understands the interaction between both chapters. This means solar installers need to study Chapter 57's location restrictions, isolation requirements, and thermal runaway mitigation alongside their existing Chapter 72 knowledge.

MCS certification interaction is important. The Microgeneration Certification Scheme requires installers to demonstrate competence in the relevant BS 7671 requirements. Amendment 4 will be incorporated into MCS standards, likely requiring MCS-certified solar installers to complete an Amendment 4 update course. The MCS Installation Standard MIS 3002 (for solar PV) and MIS 3012 (for battery storage) will reference Amendment 4 requirements.

Commissioning procedures for solar-plus-battery systems are updated. Amendment 4 requires that the commissioning test for combined systems verifies: PV string isolation does not affect battery operation, battery isolation does not affect PV generation, anti-islanding operates correctly with battery backup present, and all labelling meets both Chapter 72 and Chapter 57 requirements.

ECalPro's Solar PV Calculator is updated for Amendment 4 Chapter 72 and Chapter 57 requirements, providing solar installers with an integrated design and verification tool.