February 09, 2026

Your EV Has a Secret: The 6.6kW Solar System is Obsolete

You’ve made the leap to an electric vehicle. The silent ride, the instant torque, the freedom from petrol stations—it’s a game-changer. Then, the first power bill arrives, and you realise your new car is the single hungriest appliance you’ve ever owned, easily doubling your daily energy consumption.

The old advice of installing a “standard” 6.6kW solar system? It’s officially out of date. That system was designed for a world before every garage had a 60kWh battery on wheels waiting to be fed. To truly power your car with the sun, you need to rethink everything you’ve been told about solar sizing.

This guide isn’t about theory; it’s about the new reality. We’ll show you the exact math for your car, why your postcode drastically changes the answer, and why a 10kW to 13.3kW system has become the new gold standard for Australian EV owners.

“An electric car is the largest electrical load a household can add, often doubling daily energy consumption.”

In This Article:

What Size Solar System Do You Need to Charge an Electric Car?.jpg

Your EV’s Real “Fuel” Consumption (It’s More Than You Think)

Before you can size the generator (your solar panels), you need to understand the engine (your EV). Your car’s “fuel” consumption is measured in kilowatt-hours per 100 kilometres (kWh/100km). A lower number is better, just like L/100km in a petrol car.

But here’s the catch: the number in the brochure is rarely the number you’ll see in the real world.

Highway driving, running the air-con, and the simple physics of pushing a heavy, boxy SUV through the air can increase energy use by 20-30% compared to official figures. Aerodynamic sedans are far more efficient than SUVs at highway speeds. This is your Real-world EV efficiency.

To get a clear picture, let’s look at some popular models in Australia.

Vehicle Model	Segment	Real-World Estimates (kWh/100km)	Annual Energy (14,000 km)
Hyundai Ioniq 6	Sedan	15.0 – 16.0	~2,100 kWh
Tesla Model 3 RWD	Sedan	14.5 – 15.5	~2,100 kWh
BYD Atto 3	Compact SUV	16.0 – 17.5	~2,380 kWh
Tesla Model Y RWD	Mid-Size SUV	16.5 – 18.0	~2,400 kWh
Kia EV9	Large SUV	24.0 – 28.0	~3,600 kWh

Let’s say you drive a Tesla Model Y about 15,000 km a year. Your daily energy need at the wheels is about 7.0 kWh. But accounting for charging losses (heat generated during power conversion), your solar system actually needs to produce an extra 8.0 kWh of surplus energy every single day, just for your car.

Add that to an average Aussie home’s daily use of 15-18 kWh, and your new daily target is 23-26 kWh. That’s a big number to hit, especially in winter.

Key Takeaway: Your EV likely adds 7-10 kWh to your daily energy needs. Sizing your solar system starts with understanding this new, much higher, daily target.

The Winter Solar Trap: Why Your Location Changes Everything

Here is the most common and costly mistake people make: sizing a solar system based on a yearly average. Your car needs charging in June just as it does in January, but your solar panels produce drastically less power in winter.

Solar generation follows a “bell curve”—peaking at midday and tapering off in the morning and afternoon. In winter, that curve becomes shorter and much, much flatter. This creates the “Winter Gap,” where a system that seems huge in summer can’t even cover your fridge and lights.

“Sizing a solar system for your EV based on a summer average is a recipe for disappointment.”

This effect is dramatically worse the further south you live. solar winter generation in Melbourne is a fraction of what it is in Brisbane.

City	Winter Low (kWh per day per 1kW Installed)	Summer Peak (kWh per day per 1kW Installed)	Seasonal Reduction
Brisbane	~3.1 – 4.2 kWh	~5.5 kWh	~25-30%
Sydney	~2.5 – 2.8 kWh	~5.0 kWh	~45-50%
Perth	~3.0 – 3.5 kWh	~6.4 kWh	~45-50%
Adelaide	~2.3 – 2.6 kWh	~6.0 kWh	~55-60%
Melbourne	~1.5 – 1.8 kWh	~5.0 kWh	~60-70%
Hobart	~1.6 – 2.0 kWh	~5.2 kWh	~65-70%

Let’s see what this means for a standard 6.6kW system:

In Brisbane: On a winter day, it might generate 20 kWh. After your home uses 15 kWh, you still have 5 kWh left for the car. Not bad.
In Melbourne: That same 6.6kW system generates just 10-12 kWh. If your home uses 15 kWh (more with heating), you’re already importing from the grid before you even plug the car in. There is zero solar for the EV.

To guarantee year-round solar for EV charging Australia, you must size your system to conquer the worst-case scenario: a cloudy day in July.

Key Takeaway: Location is the single most important factor. A system that works perfectly in Brisbane will fail to charge an EV during winter in Melbourne, Sydney, or Adelaide.

The New Gold Standard: Sizing Your System for True Solar Charging

The data is clear: the 6.6kW system is not enough for a household with an electric car. It can help offset your bill, but it cannot directly power a modern EV charger while also running your home.

Here’s why:

Power Mismatch: A standard Level 2 EV charger draws 7kW of power. A 6.6kW solar system has a 5kW inverter, meaning it can only ever output a maximum of 5kW. You will always be pulling at least 2kW from the grid to charge at full speed.
Load Conflict: If your air conditioner kicks in (using 3kW), there’s only 2kW of solar power left for the car. Your charger will immediately pull the other 5kW from the grid at an expensive daytime tariff.

The Solution: 10kW to 13.3kW Systems

For any serious EV owner, the conversation now starts at 10kW of panels. A system with 10kW to 13.3kW of panels paired with a quality 10kW inverter like the SolaX X1-Hybrid G4 Inverter is the new sweet spot.

Winter Power: A 13.3kW system in Melbourne can still produce 18-22 kWh on a winter day. That’s enough to cover the home’s 15 kWh base load and still leave 3-7 kWh for a typical daily commute.
Charging Headroom: With a 10kW inverter, your system can deliver 10kW of power. This allows your 7kW EV charger to run at full solar speed, while still leaving 3kW to power your home simultaneously. This is true energy independence.