Night-rate tariffs plus batteries can arbitrage grid prices — if automation and maths align.
How night charging works
Time-of-use tariffs offer cheap overnight import — often 7–9p/kWh in 2026 on some products versus 28p+ peak. Batteries charge from grid at night and discharge at peak, optionally topped up by daytime solar. Software schedules matter; manual toggles fail quickly.
Interaction with solar
Priority is usually solar self-use first, then grid top-up at cheap rates, then peak discharge. Summer may fill batteries from solar alone — winter relies more on night import economics.
When maths works
| Factor | Effect |
|---|---|
| Peak/off-peak spread | Wider spread improves case |
| Battery round-trip loss | ~10% reduces margin |
| Standing charges | Erode small-home gains |
| EV on same tariff | Competes for cheap slots |
Tariff change risk
Suppliers revise time-of-use bands — automation should adapt, but annual review keeps assumptions honest. Exit fees may apply when switching.
Night charging is a spreadsheet strategy — enthusiasm without half-hourly data disappoints.
Battery requirements
Not all batteries accept grid charging — confirm hybrid inverter modes and warranty allows grid import cycling.
Agile and dynamic tariffs add volatility — some households prefer fixed simplicity.
