Cole3 min read

Charging an EV from solar: a real day, hour by hour

One sunny Saturday put 22 kWh of rooftop solar into our GWM Ora 5, about 140 km of driving. Here's how the day played out, what it saved, and the one catch for your home battery.

What does charging an EV from your own roof actually look like? We replayed a sunny Saturday from our home system's data: the car plugged in mid-morning and soaked up the sunshine all day. The full story, with a second day for comparison, is on The Electric Shed: A day in our solar house, with and without the EV.

A day in our solar house, hour by hour, from The Electric Shed on YouTube.

The short version

  • 22.4 kWh into the car in one sunny day, 21 kWh of it straight from the roof: about 140 km of driving in our Ora 5 (16 kWh/100 km).
  • It charged at 3–6 kW, following the sun, from 9:43 am to 3:48 pm.
  • It saved about NZ$2 against charging overnight from the grid, and about NZ$35 against petrol for the same distance.
  • The catch: on car days, the home battery doesn't fill. Ours stayed at 46% while the car charged and reached 76% by sunset.
The replay at 1:30 pm: 7 kW of sun, 6.4 kW going into the car, the home battery holding at 45%.
1:30 pm: most of the sun goes into the car.

The day

  • 9:43 am: plugged in. The home battery had already taken the early sun and was about 40% full.
  • Midday: a few clouds; the charging rate rose and fell with the sun, between about 3 and 6 kW.
  • 3:48 pm: done, with the car at 71% (from 38%). The home battery then filled to 76% by 7 pm and ran the house overnight.
  • All day, we bought 1.3 kWh from the grid (NZ$0.33) and sold almost nothing.

What it was worth

  • Instead of the grid overnight: 22.4 kWh × 22c = NZ$4.92. Selling the same sunshine would have earned about NZ$2.96 at our 14c export rate. So the sunny charge was worth about NZ$2.
  • Instead of petrol: 140 km at 7 L/100 km is 9.8 L; at NZ$3.61/L (91, October 2026), about NZ$35.

The rule of thumb: compare what export pays you with the cheapest other way you can charge. In New Zealand and Australia, where feed-ins are low, charging from the sun usually wins. On a Solar Sharer plan in NSW, south-east Queensland or South Australia, midday grid power is free for three hours anyway.

Sell it or drive it: the sums with our real numbers.
Sell it, or drive it?

If you're charging at home, our GWM Ora 5 review covers how this car charges, and how long EV batteries last covers what years of charging do to the battery.

Sources

Diagrams and replays: The Electric Shed.

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