A charger that diverts surplus generation into the car turns exported kilowatt-hours into kilometres. When the car charges in daylight off your own array, the marginal cost of those kilometres gets very close to nothing.
Plenty of wall boxes are a switch with an app bolted on. The useful ones read what the house and the array are doing, and follow generation instead of the clock.
Surplus goes to the car, not the grid
The charger watches generation against household load and puts the difference into the battery on wheels. You skip selling a kilowatt-hour cheaply at noon and buying one back expensively at night.
Or set a floor and let it top up
Charge purely on surplus and accept a slower week when it is overcast, or nominate a minimum state of charge so the car is always ready. Which mode suits you depends on how far you drive, not on the hardware.
Single-phase covers most driving
Overnight on single-phase is enough for the majority of Australian commutes. Three-phase is worth it if the supply is already there and you regularly need a large charge in a short window.
One app for roof, battery and car
Because the charger comes from the same manufacturer as the inverter, you are not reconciling two apps that disagree about what the house did this morning.
Solar charging works best when the car is home in the middle of the day.
If it leaves at seven and comes back at six, most of your charging happens in the dark and the sunlight story only really holds on weekends — unless you have a battery in between, which changes the arithmetic entirely.
It still works well for a lot of households: people working from home, a second car that mostly does school runs, or anyone on a retail plan with a cheap overnight window. Just do that sum before you spend, not after.
Worth working out first
- When the car is genuinely parked at home on a normal week.
- Roughly how many kilometres you drive, and how much charge that needs.
- Whether the switchboard has capacity, or needs upgrading first.
- How far the charger sits from the board — the cable run is a real cost.
- Whether a battery would do more for your bill than a charger, at similar spend.
Charging pattern, driving distance and your tariff decide whether a solar-diverting charger pays for itself quickly or slowly. We would rather model it than sell you one on the strength of the idea.