It depends on your setup. A standard battery installation will shut down during a power cut because the inverter must disconnect from the grid for safety (to protect engineers working on the lines). However, batteries with Emergency Power Supply (EPS) functionality keep your home running.
How EPS works — When the grid goes down, an EPS-enabled system automatically isolates your home from the grid within seconds and switches to battery power. Your lights, fridge, heating controls, internet router, and other essentials keep running as if nothing happened. When the grid comes back, the system reconnects automatically.
How backup works on the systems we fit:
- Tesla Powerwall 3 — backup needs Tesla's backup gateway. With it installed, the switchover is seamless. - Sigenergy SigenStor — backup uses the Sigen Gateway, set up for the whole home or prioritised circuits. - Other hybrid systems — backup depends on the exact inverter and backup hardware.
How long will it last? — A fully charged 13.5kWh Tesla Powerwall can power essential loads (lights, fridge, router, phone charging, heating controls) for 12-24 hours depending on usage. If your solar panels are generating during the outage, the battery recharges during the day and can keep you going indefinitely.
Rural properties — This is one of the most popular reasons our customers in Stirlingshire, Perthshire, and the Trossachs invest in battery storage. Power cuts in rural Central Scotland can last hours or even days. EPS gives you complete peace of mind.