Inverters & components
Anti-islanding: the safety function that protects the grid
Anti-islanding is one of those behind-the-scenes safety functions that rarely gets explained, but it's central to why grid-connected solar — including plug-in solar — is regulated the way it is.This guide explains what it is and why it matters. It connects closely to G98 notification and the legal status.
Written and edited by Christopher Panteli
Christopher is the founder and editor of MyPlugInSolar. He oversees the site’s research standards, data tools and editorial process. He is not an electrician or solar installer, and specialist technical claims are sourced from official documentation or reviewed by appropriately qualified professionals.
What 'islanding' means
If the grid supply fails — say, during a fault or maintenance — any generation still feeding the wires could keep a section live, creating an unintended 'island' of powered cable. That's dangerous: network engineers expect dead wires to be dead, and back-feeding can damage equipment.
How anti-islanding protects everyone
A compliant grid-connected inverter constantly checks the grid's presence and characteristics. If it detects the grid has gone, it stops feeding in and disconnects within a defined time. This anti-islanding behaviour is a core requirement of inverters used for grid-tied generation, and microinverters used in plug-in systems include it.
Why it matters for plug-in solar
Because plug-in solar feeds your home's electricity, the same grid-protection principles apply as for any grid-connected generation. This is part of why connection is notified under G98 and why plug-in solar is not yet legal to use in the UK while the rules are settled — see the legal status.
Safety and compliance
Frequently asked questions
- What is anti-islanding protection?
- It's a safety function that makes a grid-connected inverter detect when the grid has gone down and disconnect automatically, so it can't keep wires live. This protects people working on the network.
- Do plug-in solar microinverters have anti-islanding?
- Compliant microinverters used for grid-connected generation include anti-islanding as a core function. It's one of the protections that makes connecting generation to the mains safe — and it's part of why connection is regulated.
Sources
- 1. Engineering Recommendation G98 (connecting small generation) — Energy Networks Association
- 2. BS 7671 Requirements for Electrical Installations (IET Wiring Regulations) — Institution of Engineering and Technology
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