Can I charge my home battery from the grid at 2am or other off-peak times?
Often yes, if the battery/inverter platform supports grid charging and the system is configured to allow it. Australian Government guidance explicitly recognises tariff arbitrage: charging from low-cost grid electricity in off-peak periods and discharging during expensive peak periods.
Australian Government tariff-arbitrage guidance →
Why doesn't every battery do it automatically?
Many systems default to solar self-consumption: excess PV charges the battery during the day, then the battery supports the home later. Grid charging usually requires either a TOU/time-based mode, an explicit grid-charge permission, or an energy-management strategy that predicts when cheap grid charging is worthwhile.
Examples from current OEM platforms
GoodWe: its Australian TOU guidance shows owners how to set charge/discharge periods, days, SOC cut-off and charging power in SEMS+.
Fronius GEN24 Plus: time-dependent battery control can define charging/discharging windows and allows grid charging depending on tariff and system settings.
Older Sungrow hybrids: Sungrow's SH5K-20 manual documents “Forced Charge” during a time period, recommending off-peak tariff periods and charging from grid when PV is unavailable, subject to the configured target SOC.
GoodWe TOU example → · Fronius time-dependent control → · Sungrow forced-charge example →
Why might a 2am charge schedule still fail?
Check whether grid charging is permitted, whether the charge window crosses midnight correctly, whether a target SOC has already been reached, whether another control mode has priority, and whether a VPP/retailer controller is managing the battery. On Fronius, for example, a 22:00–06:00 rule has to be represented as two rules because one time window cannot cross midnight.
Does cheap overnight grid charging always make sense?
No. If the battery will refill from free or low-value excess solar the next day, filling it from the grid overnight can leave less room for solar. A tariff-optimised strategy should therefore consider tomorrow's likely solar, expected morning/evening load, off-peak price and peak price rather than assuming “cheap = fill to 100%”.