The UK tightens rules for small-scale energy storage systems. New certifications, factory testing and cybersecurity requirements are on the way

The UK certification body MCS has launched an industry consultation on a new product standard for energy storage systems. The regulations will cover the residential prosumer segment as well as small and medium-sized commercial BESS installations. Until now, certification in the UK has covered installer qualifications and photovoltaic panels themselves, while the energy storage market has operated within a regulatory gap. The change aims to bring these requirements into line and improve end-user safety.

Cybersecurity, factory audits and stringent standards

The new standard is intended to cover both systems with integrated inverters and standalone battery storage systems. The proposed standard imposes a range of stringent requirements on manufacturers:

• Safety and transport standards – compliance with IEC 62619 (lithium cell safety) and UN 38.3 (transport safety for lithium and sodium-ion batteries) will be required.
• Cybersecurity – devices with wireless connectivity (Wi-Fi, Bluetooth) will have to comply with ETSI EN 303 645. This includes, among other things, a complete ban on default passwords, mandatory protection of data transmission to and from the cloud, and a system for regular software updates.
• Production control and audits – as with PV panels, manufacturers will have to subject their facilities to regular factory inspections to confirm that mass-produced batteries are consistent with the samples tested.
• Transparency of performance parameters – manufacturers will be required to declare the expected service life, round-trip efficiency and usable energy capacity where this differs from the nominal capacity.

The Energy Storage Association supports the introduction of the standards. Experts emphasise that most reputable brands already hold certifications from independent bodies (such as TÜV), meaning that the MCS requirements are more likely to serve as local confirmation of quality than as a barrier to market entry.

Transition period for the market

The public consultation will run until 10 November 2026. Once it has concluded, MCS plans to introduce a transition period for installers to give manufacturers time to complete the certification processes and bring appropriately labelled products to market.