Island mode is the operating state in which a normally grid-tied battery system automatically disconnects from the utility grid on detecting a grid failure, then continues to supply power to a defined set of local loads from its own battery and on-site generation until the grid is restored.
Why it matters for home backup power
For homes and businesses where grid outages can be prolonged and unscheduled, island mode is what turns a grid-connected battery into a live backup. A pure Сетевой режим (grid-tie) inverter must shut down the instant the grid fails: its anti-islanding protection requires it to stop exporting, so that no live voltage reaches distribution lines that utility workers believe are de-energized. Island mode adds a controlled second step. After confirming grid failure, the inverter opens the grid-side relay and then forms a local AC supply on the load side, keeping connected circuits live without energizing the dead utility line. The switchover is automatic, typically completing within milliseconds to a few seconds, with no action needed from the occupant.
Island mode in practice
Key numbers
The battery behind an island-mode system must be sized to the actual loads it will carry. Genixgreen LiFePO4 systems run at a nominal 51.2 V and are rated for 6000+ cycles, scaling from about 5 kWh to 16 kWh for homes and into the MWh range for commercial sites. For planning purposes, usable energy is about 85 percent of nameplate, reflecting depth of discharge of 80 to 95 percent combined with one-way discharge and inverter efficiency of 90 to 95 percent. Backup duration in any installation depends entirely on the connected load.(Source: Battery University BU-808)
Island mode vs off-grid: the critical distinction
These two terms describe different configurations, not two names for the same thing:
- Автономный режим (off-grid): no utility grid connection at all, by permanent design. The battery and on-site generation are the sole power source at all times, even when the wider grid is fully operational.
- Автономный режим: the system is normally grid-tied and synchronized with the utility. It creates a local power island only when the grid fails, then reconnects automatically once the grid is stable again.
The safety mechanism that makes island mode work without violating anti-islanding rules is the grid relay: the inverter opens that relay to isolate the utility line before forming local AC output. A Переключатель резерва is the physical device that enforces this separation at the service-entry point. Installation of any grid-disconnect or transfer-switch hardware must be carried out by a qualified electrician.
How Genixgreen uses island mode
Genixgreen has built LiFePO4 storage in its own factory since 2011 and ships to 100+ countries, with local stock in Odesa for delivery across Ukraine. Genixgreen home and commercial systems support automatic island-mode switching: on detecting grid loss, the inverter opens the grid relay and resumes supplying connected loads from battery and solar within seconds, requiring no manual steps from the occupant or operator.
Related terms
- Автономный режим (off-grid): the permanent, grid-free alternative where the battery system is the sole power source at all times
- Сетевой режим (grid-tie): the normal operating mode an island-mode system uses when the grid is live
- Переключатель резерва: the physical switch that enforces the separation between the utility feed and the battery system’s local output
- Explore the Genixgreen product range to see systems with automatic island-mode switching
- Back to the Глоссарий систем хранения энергии
Sources
- Battery University BU-808: How to prolong lithium-based batteries (depth of discharge, usable capacity, round-trip efficiency and cycle-life context). https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries