Charging an electric car with solar at home: chargers, cost per km and the battery question

What does a car add to your power use?

Work it out from your car's energy figure and how far you drive. The Green Vehicle Guide lists each model's use in watt-hours per kilometre (divide by 10 for kWh per 100 km). Our example car uses 16 kWh per 100 km, so 10,000 km a year adds about 1,600 kWh, or 4 kWh a day, plus a little lost in charging. That is a big share of a typical home's use, which is why the car changes what size solar makes sense.

Which home EV charger do you need?

Three ways to charge at home, and roughly how many kilometres an hour of charging adds for the example car:

For solar, the feature that matters is solar-aware charging: the charger reads what your panels are exporting and charges the car with that spare power, speeding up and slowing down with the clouds. Most cars won't charge below about 6 amps, around 1.4 kW on single-phase, so on a dull day the charger pauses or tops up from the grid, depending on how you set it. A charger that also works with your solar inverter's brand is simpler to set up; ask your installer which ones they fit.

What does a kilometre cost from solar vs the grid?

Power from your own panels isn't free in a strict sense: each kWh the car uses is one you don't export, so it costs you the feed-in credit. At today's reference plans that gap is large in every state:

Grid figures use each state's reference usage rate; your plan may be higher or lower, and time-of-use or EV plans with cheap overnight rates narrow the gap. Every state's rates are in electricity prices per kWh.

Will your solar cover the car?

A 6.6 kW system in Sydney, Brisbane, Perth or Adelaide makes about 25 kWh a day averaged over the year (the regulator's zone rating), less in winter. The example car's 4 kWh a day would take a large share of that, leaving less for the house. Homes planning a car often go to 10 kW or more, where the roof allows: about $8,000 to $12,000 installed for 10 kW, after the federal rebate (October 2026). The catch is timing: solar charging only works when the car is home in daylight. A car that's at work all day charges at night, from the grid or a battery.

Can you charge free in the middle of the day?

In New South Wales, south-east Queensland and South Australia, the Solar Sharer Offer gives up to 24 kWh a day free during a three-hour midday window, and you don't need solar for it. A 7 kW charger running the whole window takes about 21 kWh, roughly 131 km for the example car, if the car is home. Rates outside the free hours can be higher, so compare the whole plan. Details: the Solar Sharer Offer.

Does a home battery help charge the car?

Sometimes, but it's rarely the best use of the battery. A 15 kWh battery holds about 94 km for the example car, and emptying it into the car leaves nothing for the evening at home. The usual pattern: the car takes the daytime solar, the battery covers the house after dark. If the car can only charge at night, a larger battery starts to make sense; 30 kWh costs about $15,500 to $27,500 installed after the federal battery rebate (about $5,698 off that size, as of 22 October 2026). Ask your installer whether the battery can be set not to discharge into the car. More in what size battery you need.

Using the car itself as a home battery (vehicle-to-home) needs a bidirectional charger and a car its maker approves for it. Few combinations are available in Australia so far; check with the car maker before you count on it. For keeping the house running in an outage, see home battery backup in a blackout.

What drives the cost of installing a charger?

• The cable run from the switchboard to where you park: the longer and harder the route, the more labour and cable.
• Your switchboard and supply: an older board or a home already near its limit may need an upgrade or load management.
• Single or three-phase: three-phase chargers cost more and only help if your car can use the extra power.
• Solar features: solar-aware charging and app control are standard on many chargers but not all.

The federal discounts cover the solar panels and the battery, not the charger. In New South Wales, the Home Energy Saver loan can include a home EV charger: see the NSW loan. Get the charger priced in the same quote as the solar so the installer plans the wiring once.