How Many Solar Panels You Need To Charge An Electric Vehicle (EV)?

Estimate read time: 3 minutes

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 EV. 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

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 EV 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 electric 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)

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 up the battery of the electric vehicle.

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