For the energy storage and renewables sector, the most significant update to the UK’s wiring standard in years has just landed and it speaks directly to the work we do. On 15 April 2026, the IET and BSI published Amendment 4 to BS 7671:2018, the “Orange Book,” and for the first time the standard includes a dedicated chapter on stationary secondary (storage) batteries. From 15 October 2026, all new installations must be designed and built to it.

When the UK’s national electrical standard creates a chapter specifically for battery storage, it tells you how far and how fast the sector has matured. We’ve spent the last few years helping build that market and keeping ahead of standards like this is part of how we deliver as a principal contractor.

Why we’re already across it

Our team recently attended SELECT’s annual Amendment 4 toolbox talk, hosted by Neil Sim and the SELECT team, and we’re rolling the new standard out internally across both Ener-G Services and Aberdeen Electrical Services. Regulatory currency isn’t an afterthought on our projects – it’s part of the responsibility we take on when we act as principal contractor rather than subcontractor. If we’re delivering your project end to end, the compliance picture is ours to own, not yours to chase.

What Amendment 4 changes for storage and renewable installations

A4 responds to a grid that now runs on power electronics, distributed generation and storage. The changes most relevant to BESS and renewable projects include:

• A new chapter dedicated to stationary secondary batteries. This formalises requirements for the low-voltage side of storage installations – exactly the territory where careful design, thermal management and protective measures separate a safe, bankable asset from a problem.
• Revised overvoltage protection and electromagnetic compatibility (EMC) provisions. Modern inverters, converters and control systems are sensitive, and they generate disturbances of their own. The standard now reflects the realities of high-density power electronics on site.
• Updated earthing and protective bonding requirements. Robust earthing is the foundation of safety on every site we work – from offshore platforms to transmission-connected battery parks and getting it right is non-negotiable.
• Provisions for onshore units and shore connections for inland navigation. A useful update for the marine side of our work, where electrical systems have to perform in genuinely demanding conditions.

The standards landscape a principal contractor has to manage

Here’s the nuance that matters on a real project: BS 7671 governs low-voltage installations. The grid and high-voltage connection  (the 275kV transmission interface on a project like Blackhillock, for instance) sits under a different framework altogether, including the relevant Engineering Recommendations and grid connection standards. A grid-scale storage or renewable scheme touches both worlds at once.

That’s the core of the principal-contractor argument. Someone has to hold the whole compliance picture together – the LV installation under BS 7671 A4, the HV connection under its own standards, the testing and commissioning regime, the documentation – and make it cohere into one safe, certified, on-time delivery. Splitting that across uncoordinated subcontractors is where risk and delay creep in.

Proven where it counts

We’ve delivered over 15 grid-scale BESS projects across the UK, with combined capacity exceeding 500MWh – 100% of them on time and on budget. That includes Scotland’s first grid-scale battery system (50MW in Dundee), a second 50MW scheme at Fordtown, and the UK’s then-largest battery storage system at Blackhillock – a 300MW facility connected directly to the 275kV transmission grid, making us Scotland’s only contractor with proven 275kV battery storage experience.

Across every one of those projects, the same principle applied: own the standards, own the delivery, reduce the client’s risk.

Planning a storage or renewable project?

Amendment 4 is one more reason to work with a contractor who lives in the detail. If you’re a developer, asset owner or operator planning a BESS or renewable scheme and you want a principal contractor who’ll take full responsibility for delivering it safely, compliantly and on schedule – let’s talk.

Contact our team on 01224 737294 or email sales@energservices.com to discuss your next project.