What are islanding and anti-islanding protection?

Islanding means local generation powers circuits separated from the public grid. Anti-islanding protection stops generation feeding a failed network [S1]. Safe backup needs a designed changeover and protection arrangement [S2]. Treat these as 2 separate functions when discussing your solar and battery specification: disconnection alone does not provide backup power. Checked October 2026.

Last checked 19 October 2026

What does islanding mean for your site?

Islanding is operating local generation and selected electrical circuits while separated from the public grid. Anti-islanding, also called loss-of-mains protection, prevents local generation continuing to energise a failed network [S1].

Why it matters for your site: solar panels and a battery do not, by themselves, establish that your tills, refrigeration or chargers will work during an outage. The OPSS report explains the protective shutdown function; its scope is domestic storage, so use it to understand the principle rather than specify a commercial system [S1].

Why does grid-tied solar stop during a power cut?

The inverter must avoid feeding the disconnected network. Sunshine does not remove that protection requirement. Safe intentional islanding creates a separated supply for the designated circuits; it does not disable anti-islanding [S1], [S2].

There are 2 distinct questions for your installer: how the network is isolated, and how the isolated circuits are then supplied and protected [S2]. Ask for both answers on the electrical drawing.

How can a backup battery island safely?

A backup design needs compatible power conversion equipment, switching and an appropriate earthing arrangement. The IET explains why fault protection also needs assessment when an inverter supplies the circuits. Its article covers a single dwelling; your commercial designer must assess the actual business installation [S2].

Request an essential-circuit schedule, the available backup power and energy, and a demonstrated changeover. Ask whether vehicle charging should pause to preserve the reserve. Do not assume an interruption-free supply.

Use business battery backup for runtime planning and G98 versus G99 for the generation connection process. A distribution network operator (DNO) manages your local network; G99 is the engineering recommendation for generation connected in parallel with it [S3].

Next step

Prepare the circuits you need to keep running using the site check, then get matched with an installer that covers your area.

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