Solar EV charging: which chargers can use your excess solar?

How solar EV charging works

A solar-aware charger measures how much power your home is sending back to the grid, usually with a sensor at the switchboard, and adjusts its charging current to match. As your solar output and household use change through the day, the charging rate follows. When the surplus is too small, it pauses or tops up from the grid, depending on the mode you choose.

EV charging has a minimum current of 6 amps. On single-phase power that's about 1.4 kW, and across three phases about 4.1 kW, so a charger needs at least that much surplus before it can charge from solar alone. That's why Evnex states that excess-solar charging on the X22 starts above roughly 1.5 kW of export on single-phase and 4.5 kW on three-phase.

Which chargers can charge from excess solar

• Built in: the Evnex E2 Core and E2 Plus can prioritise excess solar on single-phase. The Evnex X22 charges from excess solar with sensors included. The myenergi zappi has ECO and ECO+ surplus-solar modes with a sensor included.
• With an add-on: the Evnex E2 Flex charges from the grid as supplied, and Evnex offers a solar upgrade. The Smappee EV Wall optimises for solar with additional Smappee monitoring hardware.
• No dedicated solar diversion: the myenergi zappi GLO integrates with solar and home energy systems, but it doesn't have dedicated surplus-solar modes.

Solar on single-phase vs three-phase

Because the minimum charging current applies to every phase in use, three-phase charging needs about three times the surplus before it can run on solar alone. The Evnex X22 uses phase switching to charge on a single phase when the surplus is smaller, so it can start from about 1.5 kW of export. The myenergi zappi and Smappee EV Wall work on single or three-phase supply in the same unit.

On a single-phase home, a 7 kW charger running on solar alone needs about 7 kW of surplus to charge at full speed. Below that, it charges more slowly from whatever surplus there is above the minimum.

Getting the most from solar charging

• Plug in during the day when you can: solar-only charging only happens while there's surplus.
• Choose the right mode: solar-only for the lowest grid use, or a mode that tops up from the grid when you need a set amount of charge.
• Use scheduling for overnight top-ups. Ask your electricity retailer which tariffs are available to you.
• Have the solar sensor fitted when the charger is installed. It sits at the switchboard, so plan it with your electrician.