Solar Panels and Electric Vehicle Charging are two separate systems, but for people interested in renewable energy they can work very well together.
Using solar panels to charge your EV can help to save you more money on electricity bills, reducing the payback period for both systems.
It also helps to further reduce your carbon footprint by relying almost entirely on renewable energy for your home and transport needs.
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How Solar Panels and Home EV Chargers Work
Solar Panels
Solar PV panels work by generating DC electricity from the sunlight and converting it to AC electricity for use in your home. Your home relies first on the energy created by the solar panels, and only draws on the power grid if your consumption exceeds their capacity.
EV Charging
In its simplest form, a Home EV Charger is connected to the electricity grid in your home through an exterior unit, typically mounted to the outside wall of your home.
When you plug your EV in to charge it draws the AC electricity being used in your home and sends it to the electric car. Inside the electric car it is converted to DC and stored in the battery.
Selecting the Right EV Charger
While any EV charger can work with solar panels by connecting with your home grid, some brands are more suited than others.
The Zappi EV Charger by MyEnergi is one of the few on the market which has been designed to meet the needs of homeowners who also have solar panels installed.
The charger, which comes in both 7kW and 22kW models, features smart Eco and Eco+ charging modes for homes with solar or wind power.
The Eco mode is a mix of solar energy and grid energy if necessary, but can charge entirely on solar power if available. This mode monitors the electricity being generated by the solar panels and used in the home. If the surplus power available drops below 1.4kW, the charger will begin drawing some power from the grid.
Eco+ charging mode works similarly, monitoring power generation and consumption. However, if there is too much power being imported the charge will pause charging, and only resume when there is enough surplus power available.
Other Options for Using Solar to Charge Your EV
Solar Battery System
If you have a solar battery installed to go with your solar panels this will store the surplus power they generate during the day for later use.
As the majority of EV Charging is done at home in the evening or night time, this will be when your solar panels are producing less or no electricity.
Having a solar battery installed alongside your PV array can allow you to store electricity generated during the afternoon in order to use it to charge your EV at home in the evening.
Solar Battery systems can start as low as 5kW storage capacity, which won’t be of much use for charging an EV.
However, many modern battery systems have modular designs which allow multiple modules to be connected for capacities of 30kW or more.
However, as EV battery sizes typically eclipse this, getting a large scale battery system installed just for EV charging would be too costly to be of use.
DC Coupled System
Solar panels generate electricity as direct current (DC), and this is converted into alternating current (AC) by the system’s inverter for use in your home.
While the majority of EV charging and solar battery systems take their power from the household grid and convert it back to DC for storage this does not have to be the case.
It is also possible to install a DC Coupled or Off-Grid system which connects your EV charger directly to a Solar PV array or battery system.
This allows for much faster charging than drawing from the home grid, as it bypasses the need for any AC/DC conversion in your EV.
Solar Carport
A solar carport is a type of canopy covering a car parking space such as a driveway. The canopy will have solar PV panels on its roof, and can easily have an EV charger connected in order to charge your vehicle.
Synching Solar Power and EV Charging
One problem with using solar panels to charge an electric car is that the majority of electricity made by your solar panels will be during the mid-afternoon. This is also the time when people are most likely to be at work or otherwise out of the house.
If you are not making use of a Solar Battery then you can still reduce or eliminate the cost of charging you EV at night by selling surplus electricity from your solar PV array back to the grid.
Selling Surplus Power & Night-Time Charging
One option for your solar is to sell the surplus electricity from your solar panels generated in the day time back to the national grid. Charging of your electric car should only be done at night to avail of the cheaper night rates available on certain electricity plans.
Depending on who your electricity supplier is and what rates they have available, it is still feasible to come out ahead financially and turn a profit after charging your vehicle.
| Electricity Provider | Feed In-Tariff c/kWh | Cheapest Night Rates c/kWh | Difference |
| Pinergy | 25c | 5c | 20c |
| SSE Airtricity | 24c | 18.77c | 5.23c |
| Energia | 24c | 8.87c | 15.13c |
| Bord Gáis | 18.5c | 8.65c | 9.85c |
| Flogas | 18.5c | 20.91c | -2.41c |
| Electric Ireland | 21c | 10.13c | 10.87c |
However, when relying on night time charging rates for your EV, it is very important to research closely what timetable is offered with your plan.
Some providers such as Pinergy, Energia, Electric Ireland and Bord Gais for instance advertise a special EV charging tariff among their smart plans. But this tariff is only applicable to a very short window, typically lasting from around 2am – 4am/6am.
When gauging whether they will break even or turn a profit using this method a person should study beforehand just how much they typically charge their car during the night. How much surplus electricity is produced by your panels must also be known beforehand.
Using Your Electric Vehicle as a Solar Battery
This might not seem like a natural fit, using your EV to store and later use or sell electricity generated by your solar panels, but it is possible with the latest bi-directional EV chargers.
Bi-directional chargers allow electricity to flow both into and out of the EV, either for use in your home or for dropping back into the grid.
If your car is sitting at home most of the day, during the time when solar panels are producing the majority of their electricity, you can charge the battery with the surplus power they generate.
Vehicle-to-Grid (V2G) functionality allows for power to be fed back into the grid during peak demand times, helping to balance the grid through decentralised power generation.
Vehicle-to-Home (V2H) functionality allows you to use the electricity stored in your EV during peak demand periods when electricity tariffs are higher for anyone with a smart plan.
As a solar battery can add €2,500 or more onto the cost of a solar PV array, using your EV as a makeshift battery could potentially be a money saver.
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