You sell a kilowatt-hour for a feed-in tariff at noon and buy it back at the retail rate at seven. A charger that diverts the surplus straight into the car skips both halves of that trade.
Plenty of chargers are a switch with an app on it. The useful ones read the meter, so charging follows generation rather than the clock.
Divert the surplus instead of exporting it
The charger watches what the array is making and what the house is using, and puts the difference into the car. On a low feed-in tariff, a kilowatt-hour is worth far more in your battery or your boot than it is sold back to the grid.
Solar-only, or topped up from the grid
Charge purely on surplus and accept that a cloudy week is slower, or set a floor so the car is always ready by morning. Which mode you live in usually depends on how far you drive, not on how the charger is configured.
Single-phase or three-phase
A single-phase charger suits most homes and most overnight driving. Three-phase makes sense where the supply is already there and the car can take it. Your electrician will tell you which your switchboard supports.
OCPP, so you are not locked in
Open Charge Point Protocol is the standard that lets a charger talk to management platforms other than the manufacturer’s own. It matters more for fleets and workplaces than for a single home, but it is the right default either way.
Solar charging works best if the car is home during the day.
That is the whole trick, and nobody selling chargers likes saying it. If the car leaves at seven and returns at six, most of your charging happens in the dark, and the sunlight story only holds up on weekends or with a battery in between.
It still adds up for plenty of households — people who work from home, a second car, a household that charges on the weekend. But it is worth doing that arithmetic before you spend, not after.
Worth checking before you commit
- When the car is actually parked at home, on a normal week.
- Whether your switchboard has capacity, or needs an upgrade first.
- Whether your retailer offers an EV or overnight tariff that changes the maths.
- How far the charger sits from the board — cable runs are not free.
- Whether a battery would do more for you than a charger, at the same spend.
Because the charger comes from the same manufacturer as the inverter, you are not reconciling two apps that disagree about how much power the house used this morning.