A 7 kW charger can draw more power on its own than a 6.6 kW system makes at its best moment of the year. If charging on sunshine is the point, the system has to be sized for it.
Why
The house goes first
A solar-aware charger runs on surplus — whatever's left after the fridge, the aircon and everything else has taken its share. On a 6.6 kW system that surplus is often only two or three kilowatts, so the car trickles instead of charging.
Winter
A fraction of summer
The same array that makes 40 kWh on a long December day can make a quarter of that in June, on a shorter day. A system sized to just cover the house in summer has nothing spare for a car in winter.
The number
Aim for 14 kW
If you want the car genuinely running on your own power most of the year, that's the size to plan around. Below about 10 kW you'll be charging from the grid more often than not, whatever the charger promises.
Four things that make solar charging actually work.
Charge in the middle of the day, not at 6pm — a timer beats a habit.
Use a solar-aware charger (a Zappi or a Sigenergy) so it follows the sun instead of ignoring it.
Check your inverter's export limit before you add panels, because some network areas cap what you can install.
And if the car is usually gone during the day, a home battery is what moves that sunshine to the evening — otherwise you're charging on a tariff, not on solar.
Not sure what your system makes? Send us a photo of the inverter with your quote and we’ll tell you.
