A natural pair, with a timing catch
Solar panels and electric vehicles seem made for each other: make clean electricity on your roof, drive on it. In Alberta the pairing does make sense, but there is a timing catch worth understanding before you plan.
Solar produces in the middle of the day. Most commuters' cars are at work in the middle of the day. So on a typical weekday, your solar surplus is exported to the grid for a credit, and your car charges overnight from the grid.
That is fine. Alberta's net billing system is built for this. Your summer exports earn credits that offset the energy you import, including for charging. See Alberta micro-generation explained. Over a year, the solar can still cover much of your driving energy on paper, even if the electrons do not go straight into the car.
When the car does charge from the sun
If you work from home, drive a second car that stays home, or charge on weekends, a solar-aware charger can follow your surplus. It watches what your solar is producing and what the house is using, and sets the charging rate to soak up the difference.
Whether that is better than exporting and importing later depends on your retail plan. If your export credit and import rate are similar, the money difference is small. If they differ, charging from surplus can be worth more. Either way, it is a nice feature, not a requirement.
Surplus charging needs a way to measure exports, usually a current sensor at the panel or a link between the charger and the inverter. Not every charger or inverter supports it, so choose equipment with this in mind if it matters to you.
Some households simply use the charger's schedule instead: on sunny weekend days they set charging for late morning to mid-afternoon. It is less precise than true surplus tracking, but it costs nothing and works with almost any charger.
What it means for your electrical panel
Adding both solar and an EV charger puts two separate demands on your panel, and older Edmonton panels can run into both limits at once.
- The EV charger is a continuous load that must fit within your service in the load calculation, or be controlled by a load management system. See can my panel handle an EV charger.
- The solar system back-feeds the panel. The code limits how much based on the panel's bus rating and main breaker. A smaller panel can cap the solar size.
When either limit is reached, the options are EV load management, a different method of connecting the solar that the code allows, or a service upgrade. If you are doing both projects within a few years, plan them together. One well-planned upgrade is usually better value than two rounds of panel work.
Sizing solar to cover your driving
To include an EV in your solar sizing, estimate how much energy the car will use in a year:
- Estimate your yearly kilometres, including winter.
- Find your car's typical energy use per 100 km, and assume it will be noticeably higher in winter. See EV charging in an Edmonton winter.
- Multiply, and estimate how much of that charging happens at home rather than at work or public chargers.
- Add that to your household's annual use before sizing the solar.
Because Alberta's rules expect systems to match your own consumption, documenting the EV as new load helps justify the size. Your installer can explain how. Our guide to sizing a home solar system covers the rest of the process.
Bidirectional charging: what to know now
Some newer EVs and chargers can send power back out of the car, either to run the house during an outage (vehicle-to-home) or, in future, to the grid. It is an exciting idea, especially for backup in a long winter outage.
It is also still early. For it to be used safely in Alberta, the car, the charger and the transfer equipment must be certified for that use in Canada, the setup must isolate the house from the grid, and anything that can export needs the wire owner's approval. Rules and products are changing quickly.
Do not use adapters or inverters to feed your house from an EV through an outlet or dryer receptacle. Back-feeding without proper isolation can energize utility lines and seriously injure line workers. Use a properly installed, approved system only.
If backup power is the goal today, a battery storage system or a standby generator is the proven route. See home battery storage in Alberta.
A sensible order of operations
- Get a load calculation that includes the EV, solar and anything else planned.
- Decide whether a service upgrade or load management is needed.
- Install the EV charger, choosing one with solar-aware features if you want them.
- Design and apply for solar, with the EV included in your expected use.
Doing it in this order means the panel work happens once, the charger is working while the solar paperwork is processed, and the solar design reflects how your household actually uses energy with the car in the picture.
Alberta Electrical installs both home EV chargers and residential solar, so one team can plan the whole picture with you.
Common questions
Will my EV charge directly from my solar panels?
Only when the car is home and plugged in during the day. Most commuters charge overnight from the grid and use solar export credits to offset that energy on the bill.
Do I need a special charger to use solar?
No. Any charger works with solar through net billing. A solar-aware charger is only needed if you want the car to follow your surplus in real time.
Can my EV power my house in an outage?
Only with a vehicle, charger and transfer equipment that are certified for it and installed with proper grid isolation. The technology is emerging, so check current options with us before buying.
Should I install solar or the EV charger first?
Plan both together, then usually install the charger first since it is quicker. The solar design can then include the EV's expected energy use.
Codes and permit rules change and every building is different. For work on your system, talk to a licensed electrician and your local permit authority.