Sizing Solar + Battery to Charge an EV at Home | Greenlight

 An electric car is often the single biggest new electricity load a home ever adds. It can quietly double your daily power use. So the question we hear constantly from EV owners across New South Wales and Queensland is a fair one: how much solar, and how big a battery, do I actually need to run the car on sunshine instead of grid power?

The honest answer is that it depends on one thing above all else: when you charge. Charge in the middle of the day and you can run mostly on live solar with a smaller battery, or none at all. Charge overnight and the battery becomes the fuel tank, which changes the sizing completely. This guide from Greenlight Solar walks through the numbers, with real figures for NSW and QLD roofs, so you can work out what your own setup needs.

Start with how much energy your EV really uses

Charger power ratings (7kW, 11kW, 22kW) tell you how fast a car charges, not how much energy it needs. For sizing solar, the number that matters is kilowatt-hours (kWh), and it comes from how far you drive.

Most EVs in Australia use between 14 and 20kWh per 100km in real driving. A small hatch sits near 15kWh, a mid-size SUV closer to 18 to 20kWh. Using 18kWh per 100km as a safe planning figure, here is what different driving habits demand each day:

Daily driving	Energy the EV needs per day
20 km (light)	~4 kWh
40 km (average commute)	~7 kWh
60 km	~11 kWh
100 km	~18 kWh
150 km (heavy)	~27 kWh

The average Australian drives about 36km a day, which works out to roughly 6 to 7kWh. Many households land in the 40 to 80km range once you count the school run, work and errands. Check your own odometer over a week and you will have a far more accurate figure than any average.

Read More: https://www.greenlightsolar.com.au/solar-battery-for-ev-charging/