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The Number Of Solar Panels You Need To Charge An Electric Vehicle

By Kristy Hoare on in Electric Vehicles

The Number Of Solar Panels You Need To Charge An Electric Vehicle

solar panels on home with tesla ev charging station

Demand is increasing for electric vehicles (EV’s) and solar power; many New Zealanders are considering environmentally friendly options when powering their homes and cars. Solar power is a great investment, especially when benefitting from two technologies (solar powered homes/electric vehicles).

In this article, we discuss certain factors to consider when purchasing (or thinking about purchasing) a solar power system to charge your vehicle. We’ll also answer how many solar panels are needed to ensure an efficient charge (we get asked this question a lot). The numbers below are only estimates, so allow for numbers to change due to individual driving styles and unique roads driven. Keen to complete the calculations yourself? Please use the numbers below as a guide or the easier option is to request 3 free quotes for solar power, and ask the solar companies to figure it out for you.

Determining how much solar power will be required for each kilometer travelled is an excellent place to start. Varying amongst models, an average of 6km is expected out of 1kWh of power. Below is a chart that shows the km/kwh for common models.

Electric Vehicle Models And Kilometers Per Kilowatt Hour

Electric Vehicle Model Average Range (kms) Battery (kWh) Kms per kWh
Hyandai Ioniq 201.17 28 7.4
Mitsubishi i-MiEV 96.56 15 6.4
Chevrolet Bolt EV 383.02 60 6.4
Nissan Leaf 2018 241.4 38 6.4
Tesla Model 3 450.62 72 6.3
Tesla Model S 386.24 72.5 5.3
Volkswagon E-Golf 201.17 32 6.3


New Zealand’s average driver travels 28km per day. As an example, Nissan’s Leaf from 2018 shows that 4.4kWh of solar power generation is needed to fuel the car daily, which equals 1752 kWh per year.

Calculations for the above results:

28 km / 6.4 kWh = 4.4 kWh
4.4 x 365 days = 1752 kWh

Remember, these numbers are just estimates, a user may need to produce more solar power if any loss of power occurs in the internal charging system of the car.

If the yearly average of 1752kWh is needed to power an EV, select any of the system sizes listed below, in any region. They will all generate enough electricity (in theory) to power the NissanLeaf with 100% solar power. A small, 1.6kW solar power system in Dunedin can produce enough power to charge an EV. Using the example of the Nissan Leaf, we can see that there will be extra energy left after charging (enough to power electric appliance etc). 

Approximate Yearly Generation From Different Solar Power System Sizes & New Zealand Regions (in kilowatt hours)

Approximate Yearly Generation From Different Solar Power System Sizes & New Zealand Regions (in kilowatt hours)
System size 1.6kW 2kW 3.2kW 4kW 5kW 6kW 7kW 8kW
Auckland 2321 2861 4617 5858 7254 8805 10,075 11,673
Wellington 2125 2610 4218 5364 6643 8074 9215 10,681
Christchurch 2100 2587 4178 5303 6564 7979 9112 10,566
Dunedin 2095 2581 4168 5291 6547 7961 9090 10,541

Another fact to consider is that solar power systems won’t produce the same amount of power every day. Typically, they produce twice the amount of electricity in summer compared to power generation in winter months.

On the occasional winter’s day, an EV might not be running on 100% solar. For example, a 2kW system in Auckland is estimated to produce 2861 kWh of solar power a year, which is a daily average of 7.8kWh. However, in June the average daily power production will be 4.46 kWh, which is just shy of the power required by the Nissan Leaf (4.8kWh).  

Not to worry, it just means that come June you might need to draw a small amount of power from the grid to top that battery up.

Graph of Solar Production Over A Year From A 2kW system in Auckland

How Many Solar Panels Are Needed To Charge An EV?

Once system sizing has been determined, figuring out how many panels will be required comes next.  Solar panels (currently) available in New Zealand typically range between 200W and 300W. There is 1000W in a kW, so a 2kW system is needed for 10 x 200W solar panels.

If confused or concerned, a solar power expert from My Solar Quotes’ installer network can work out the technical, or the not so technical stuff for you!

References:

https://cleantechnica.com/2018/06/30/what-are-the-most-efficient-electric-cars/

http://www.gw.govt.nz/assets/NZ-Electric-Car-Guide-4April2017.pdf

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