Glossary
Anti-islanding
An inverter's automatic shut-off when the mains supply fails, so it can't feed power into a dead network. Also called loss-of-mains protection.
“Islanding” is when a generator keeps powering part of the network after the mains supply has gone off, creating a live “island”. That’s a danger to people repairing the network, who expect the lines to be dead. Anti-islanding, called loss-of-mains protection in G98, makes a grid-connected inverter detect the loss of supply and switch off.
Plug-in kits must meet G98’s technical and type-testing requirements. For plug-in micro-generators, the amended G98 drops the usual on-site functional check of loss-of-mains protection, among other installer checks (Ofgem decision). So the protection relies on the kit’s type testing, which is one more reason to buy a kit listed as Compliant on the ENA Type Test Register (IPS §7).
In practice, a plug-in kit stops producing during a power cut, even in full sun. It won’t keep your lights on, and battery kits that could are outside the GB rules (SI 2026/848).