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How much solar energy do I need to charge my EV?
Understanding how to use a solar system to charge your electric car doesn’t need to be complicated. Here’s how to maximise energy efficiency when charging your EV.
Charging your EV using solar power is quite simple. It draws energy from your solar system just like any other appliance, whether you’re plugging into a standard power point or using a dedicated EV home charger.
Read on to learn more about using solar panels to charge your EV, including whether it saves you money, how many solar panels you’ll need, and how to get them installed.
Electric cars can be charged using renewable solar energy
Using solar energy to charge your EV: FAQs
Can you use solar panels to charge an EV?
Yes, solar panels can charge EVs. Energy produced from solar photovoltaic (PV) panels goes to the solar system’s inverter. This inverter converts the energy into alternative current (AC) electricity, which can be used to power your EV and your home.
A smart EV charger has different modes that allow you to charge with solar power only, with a combination of solar and grid power (prioritising solar), or by a certain time the next day.
How do I make sure I have enough solar energy left to power my home?
If you want to prioritise using your solar energy to power your home, you can set your charger to only charge your EV battery when there’s excess solar power available.
It may cost more to charge your EV from public charging stations compared to charging it at home from solar energy. Image: Getty
Does charging your EV from solar power save money?
Charging your EV from solar power can save EV owners money over time. Without solar, EV drivers will need to charge their EV from public charging stations or from non-solar household electricity bought from the grid.
Public charging stations are still generally cheaper than filling up a tank at a petrol station, especially since RACV Members save at Chargefox ultra-rapid charging stations across Australia. Charging your EV at home, however, can be more affordable than relying solely on public charging stations.
The cost of grid power usually increases over time, but solar panels can keep producing energy without additional costs. If you do need to charge your EV without a solar system, time-of-use tarrifs may allow you to charge your vehicle when electricity is cheapest (usually late at night), potentially saving you money on your energy bill.
How many solar panels will I need to charge an EV?
How many solar panels you need to charge your EV depends on the following factors:
- Your EV’s battery size and energy efficiency – The average EV consumes up to 20kWh per 100km, which is 5km/kWh. For reference, here are some of Australia's most popular EVs and their average kWh/100km:
- Tesla Model 3: 14.4 (RWD) - 14.7 (Long Range)
- Tesla Model Y: 14.6
- MG4: 14.6
- BYD Atto 3: 16
- BYD Dolphin: 16.5
- Your driving habits – The average Australian drives 36.4 kilometres every day. You may drive more than this if you have a long daily commute, drive for work, or go on road trips.
- Your solar system’s efficiency – Solar panels with a higher wattage can generate more power than lower wattages. A 5kWh solar system in Melbourne generates around 7,000kWh per year, which averages out to around 20kWh per day.
- Your household’s average energy consumption – The average Australian home energy use is around 15-20kWh per day.
- Your location’s sunshine hours – The more sun your roof receives, the more energy your rooftop solar panels can produce.
Using the Australian average driving range of 36.4km per day, and the standard EV battery efficiency of 5km/1kWh, you will need around 7.3kWH per day to charge your EV. Add that to the average household energy consumption – so that you’re still powering your household lights and appliances – and you’re looking at 22.3-27.3kWh per day.
This exceeds the output of a 5kWh solar system, so you may need to look at a larger solar system to offset both your home and EV charging. Even if you’re just considering transitioning to an EV in the next 12-24 months, getting a larger solar system installed may be a good move.
Smart EV home chargers make owning an EV easy. Image: Shannon Morris
How long does it take to charge an EV using solar power?
Single-phase dedicated AC chargers provide a maximum speed of 7kWh for single phase supply, while three-phase AC chargers provide a maximum charging speed of 22kW. The overall charging speed is dependent on vehicle’s specifications (often limited to 11kW from AC charging) and the output capacity of the solar panels.
Using the average daily driving distance above (36.4km), this would require about 7kWh to charge the EV each day. Using a single-phase dedicated AC charger, this would take just over an hour to charge. Using solar power only to recharge would take longer, depending on your solar output.
How do I install solar for charging my EV?
Contact an accredited solar provider to discuss your charging requirements and work out exactly how big a solar system your household will need. They can also help you gain access to any rebates or loans on offer from the government.
