Living off-grid with a Polestar, cheaper and more efficient than our diesel hatch

My wife and I recently drove 2,000 km in our EV from our off-grid home in Western Victoria to the central Queensland coast, averaging 500 to 600 km per day.

Energy use went from 18.5 kWh/100 km in the cold and wet south, to about 15.7 kW/h/100km in the warmer north. Rain, cold and some night driving lead to this higher power use. The cabin temperature was kept at 22 degrees.

An interesting observation is comparing our previous economic diesel hatch with the EV using MJ/100 km: an energy efficiency unit not always quoted in comparing the two types of vehicle.

The diesel hatch averaged 5L/100 km or less on a long trip. Taking the diesel energy value at 39 MJ/litre, the ICE car used about 195 MJ/100 km, whilst the energy use in the EV varied between 67 to 57 MJ/100 km.

In comparison to the diesel hatch, we were slightly inconvenienced by charging compared with filling the fuel tank which in the past could give us 1000 to 1100 km per tank.

Nevertheless, the electricity cost in travelling to Queensland was less than the equivalent amount of diesel, at about $120 for electricity versus about $180 for diesel. (Based on observed average at the time of $1.80/L).

On the other hand, charging took longer and often had to take place at a spot we would not have chosen to stop. In general though we were able to leave the car and have a walk or a cup of coffee. We probably walked further than we would have if we were filling with diesel.

We also rarely had to wait to charge, but an increased uptake of EVs without an equal increase in charging stations will become a problem for long distance travellers. On the other hand, commuters with home or work site chargers won’t face this problem. Experience so far suggests travelling from the Wimmera to Melbourne also won’t pose a problem in either summer or winter.

Running an EV off-grid

Our property is totally off grid. The solar system consists of 14.25 kW of panels and a 15 kWh lithium titanate battery system. The EV charger is a 7 kW single phase Ocular EVSE. The solar batteries need to be charged to float before power is made available for the car charger.

Charging at home is generally fine, although doing so in mid-winter has not always been successful. Before the days shortened to mid-winter and the cloud cover became almost constant, the car (which is not used on a daily basis) could easily be charged by the system.

In that particularly cloudy period, even though these batteries take up charge rapidly, by the time the batteries get charged there was not enough solar energy to divert to the car.

However, there was never a difficulty in driving the 45 km to town to charge during this overcast winter. Longer, clearer days mean that we will keep the charge up purely by solar power for all local use.

Overall, we find the Polestar is great to drive, and the rough and corrugated dirt roads we have to drive on are not creating the problem that may occur on an EV with less ground clearance. The two main criticisms are:

  1. The radio in the Polestar only gets DAB and FM – DAB is no good outside the capital cities, and the FM reception is limited- obviously meant to be offset by the internet and Google and
  2. The lack of a spare wheel. For country driving, that can lead to an anxiety greater than range anxiety.
Will Pyke
February 11, 2024
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