Electric Vehicles or EV’s, currently make up only a small percentage of all vehicles sold around the world but with most major automotive manufacturers now developing Electric Vehicles (EV) and plug-in hybrid’s (PHEV), the uptake of EV’s is set to explode over the next 5 to 10 years. Many drivers are already considering an EV or PHEV as an option for their next vehicle purchase, but concerns about price, charging, and range anxiety is holding many people back. However, with the cost of EV’s dropping, plus the benefits of low maintenance and extremely low running costs compared to traditional petrol and diesel vehicles, EV’s are looking more and more attractive to regular buyers.
EV charging from solar
One of the big drawcards, especially for those with rooftop solar, or considering getting solar, is the ability to charge an EV using your own solar power. Charging with your own electricity can essentially eliminate the ‘fuel’ cost of an EV altogether. However, in practice, this is not always as easy as it sounds. In this article we discuss the various home EV chargers available, analyse different charging options (times) to suit various lifestyles, and look at the limitations of using rooftop solar and home batteries to charge an EV. Our unique solar and EV charging calculator can help you determine how much solar you will need to charge your electric vehicle.
EV battery capacity - KWh
Before we get into detail about the different EV chargers and charge rates, it’s best to get a basic understanding of battery capacity and EV driving range. An average EV has a battery capacity of 60kWh (kilowatt/hours) which on average provides a driving range of around 350km, depending on how efficiently you drive. Lighter, more efficient EV’s can use as little as 10kWh per 100km, while high-performance EV’s like the Porsche Taycan can use 20kWh or more per 100km of driving.
Common questions around EV charging using solar and batteries
What are my home EV charging options?
What charger is best suited to rooftop solar?
How long will it take to charge my EV a rooftop solar system?
Can I use a home battery to charge an EV?
home Electric Vehicle chargers
Generally, the first thing that comes to mind after an EV purchase is what are the charging options and are they compatible with a rooftop solar system? Before we get into detail, you should know that most EV chargers are actually very simple devices that can be installed on any home or business whether you have solar installed or not. There are a few specialised solar inverters with integrated EV chargers, but we will cover these later.
The 4 main types of home EV chargers
10A Plug-in socket chargers - 1.4kW to 2.0kW
Single-phase home EV chargers - 3.3kW to 7.0kW
Three-phase home EV chargers - 10.0kW to 22.0kW
Combined solar inverter and EV charger
1. Plug-in (socket) EV chargers - 2kW
Most EV’s come equipped with a simple charger that can be used with any common 10A wall socket. These small, low capacity chargers will generally charge EV over 12-24 hours depending on the size of the EV battery and how low the battery is at the initial charging point. Most 10A EV chargers can generally charge at a maximum rate of 2.2kW, but will typically will draw from 1.7kW to 2.0kW which will add around 10 to 14km of range per hour, depending on the vehicle.
2. Single-phase EV chargers - 7kW
Home single phase EV chargers are generally small wall mounted devices which come in a variety of options and designs. Most are rated at 32 Amp which is the equivalent of 7kW of power and can provide your vehicle with a range of 40 to 50km km per hour at full charge capacity. Given the average person drives less than 50km per day, then in theory you will only need an hour or two to recharge your vehicle per day.
3. Three-phase EV chargers - 22kW
Simple three-phase home EV chargers look very similar to the wall-mounted single-phase devices and come in a variety of options and designs. These are generally rated at 32 Amps but due to have 3 phases, can supply three times as much power which is roughly equivalent to 22kW of charging power. At the full charge rate this can provide your vehicle with a range of 120 to 150km km per hour.
4. Combined solar inverter and EV charger
A recent technology is a combined solar inverter and EV charger that can directly charge an EV from rooftop solar. An integrated EV charger and solar inverter is a clever solution that eliminates the need for a separate EV charger along with additional wiring and potential electrical upgrades. The only downside is the inverter must be installed in a garage or close to the vehicle.
There are very limited options available with SolarEdge being the first mainstream inverter manufacturer to provide the unique 2-in-1 solution which can either charge from solar only or in boost mode, can charge from both solar and the grid simultaneously.
Smart EV Chargers
If you have rooftop solar installed you can use a smart EV charger to maximise your self-use. This device essentially monitors your solar generation and instead of exporting excess solar to the electricity grid, it diverts it to your EV charger. This way you do not end up drawing power from the grid during poor or intermittent weather.
How smart EV chargers work - When you plug an EV into a standard charger at home, the charger will generally draw the maximum amount of energy it can to charge the vehicle. Most dedicated EV charged are rated at 3.5kW to 7kW although the amount of solar you are generating may be much less, especially during cloudy weather. A smart EV charger, on the other hand, uses a special CT sensor which is mounted near your main electrical supply connection point to monitor the energy flow to and from the grid. Once it detects any energy flowing out to the electrical grid, it will enable the EV charger to start charging at that specific amount. However, this can change constantly due to changes in power consumption and solar generation so the EV charger is programmed to ramp the charge rate up and down to match the excess solar generation.
An emerging technology that will be rolled out over the next few years is Vehicle to Grid or V2G, using what’s known as a bidirectional charger. This sounds complex, but it simply allows energy to flow to and from your electric vehicle. Typically chargers send energy in one direction during charging, but bidirectional chargers can draw power from your vehicle if required to power your home or to help balance the grid in times of high demand - this capability is known as Vehicle to Grid (V2G).
The current problem with vehicle to grid technology is not with the chargers, but the limited number of electric vehicles that are compatible. For V2G to work, you must a vehicle that is able to accept two-way charging and there are currently only a handful of V2G compatible EV’s on the market. This technology will become a game-changer in the near future and offer a whole range of services from backing up your home during a blackout to providing grid feed-in credits and generous rebates for supplying power during times of high demand. It can also enable the owner to participate in virtual power plants (VPP) programs.
Recommended home EV chargers
The Zappi V2 charger from Myenergie is one of the smartest and most popular EV chargers on the market. It’s a clever device with three different charging modes, eco, eco+ and fast. It can also be set up as a single-phase or 3-phase charger with 1 phase charging rate from 1.4 to 7kW and 3 phase from 4.1 to 22kW.
In Eco mode, it will charge you EV using mostly your self-generated solar power while minimising the amount of grid power used. In Eco+ mode the Zappi charger will quickly adjust its charge rate to only use your own excess solar generation and will not push any grid power. This means it will pause charging if your household is consuming all the solar generation or the weather is very poor. In Fast mode, the Zappi will charge your vehicle at the maximum rate regardless of solar generation or household consumption.
EO Mini PRO 2
EO is a leading UK based manufacturer of EV chargers and the new Mini Pro is the second generation super-compact smart EV charger. Like its larger brother the EO basic, the mini is top-quality but has a price tag to match, although if you want a small discrete modern-looking charger with clever charging options then it would be hard to pass by. It has a maximum charging power of 7kW or 32A but can be ramped down if your supply circuit is limited. It’s set up and controlled via Wifi through the EO app and tells you the current charging rate and also logs your charging history.
The EO mini Pro 2 offers three charging options, off-peak charging, solar charging, and scheduled charging which can be configured to suit your requirements.
Wallbox Quasar - Bidirectional charger
For those interested in the latest cutting edge technology, the Wallbox Quasar is the first bidirectional EV charger designed for home use and is the smallest charger of its kind to offer advanced two-way charging capabilities. It has a maximum power rating of 7.4kW (32A) but it’s important to note it is only compatible with vehicles that feature a CHAdeMO DC vehicle connector.
As explained earlier, bidirectional chargers can enable the unique advantages of V2G technology but it is early days for this emerging technology so some investigation will be required to ensure its features can be utilised in your state or region. The new Nissan Leaf is one of the few vehicles with V2G capabilities. In Australia, regulatory approvals for bi-directional chargers are about to be ratified along with several V2G trials already underway.
Single Phase Vs 3-Phase grid supply
There are two main grid connection types available for homes, single-phase and 3-phase. Single-phase electricity connections are generally limited to a maximum of 15kW or 63A, while a 3-phase connection can supply up to 36kW.
Most homes in Australia, Aisa and the US have a single-phase, 240V supply, which means the maximum total energy is which can be supplied from the electricity grid is 12kW to 15kW (50A to 63A). However, you cannot utilise this full capacity to charge an EV or you will not be able to use any other appliances at the same time. If you did, every time you use a toaster or microwave the grid supply switch would trip off due to overload. For this reason, most single-phase EV chargers are limited to 32A or around 7kW. This is actually not bad unless you really need to fast charger in your home.
On the other hand, most commercial businesses have a 3-phase supply, so it’s possible to install one or more high capacity 22kW EV chargers, depending on the capacity of the buildings electric connection.