For the majority of EV drivers, we think a single-phase, 7 kW home charger is the best solution both now and in future. Here’s why.
The installed cost of a single-phase charger will always be cheaper than 3 phase.
If your energy bill is subject to demand charges, a single-phase charger has a lower chance of contributing to them.
EV charging speeds are set in 1 amp increments per phase. This means 1 amp increments on a single-phase charger vs 3 amp increments on a 3-phase charger. Smaller increments provide more accurate solar tracking and improved utilisation with lower levels of excess solar.
Read more on single vs 3 phase when EV charging from solar.
We’re used to vehicles and electronics getting bigger and faster with each new version. Physics dictates that this won’t happen with EV charging.
The amount of energy needed to move your car is governed by its weight and efficiency. The same size EV 10 years from now is likely to need slightly less charging power each day due to efficiency improvements.
The amount of time you have for charging is dictated by how long the car is at home overnight. With most people at home for 8+ hours each night and EVs typically requiring 2-3 hours of daily charging, you’re unlikely to need to charge faster in future than you do today.
As discussed in what speed home EV charger do I need, for almost all normal daily driving, charging from a single phase 7 kW charger overnight or during the day will provide more than enough energy.
The one time it might help you a little is when you’re going on a road trip and you wake up and realise you forgot to change the charge limit to 100% the day before. You’ve got 1-2 hours before you leave and a 3-phase charger could be charging faster, but only about 50% faster, and probably still not fast enough to fill your EV to 100% in the time before you leave. At this point, you’re looking at spending an extra 5-10 minutes at a public fast charger on your journey.
This small loss of convenience is more than offset by a cheaper charger that works better with solar every other day of the year.
You’ll probably only make this mistake once or twice, after which you’ll increase your charge limit 2 days before the road trip so you can still forget it once without causing a delay!
If you have a really large solar system, say 15 kW or more, and you regularly have lots of unused solar the loss of solar tracking efficiency just might be offset by the increased charging speed.
Whilst the average driver only needs 2-3 hours of daily charging at 7 kW, if you regularly drive long distances (e.g. 200+ km per day) then a 3-phase charger might make it easier to limit EV charging to cheap off-peak periods for overnight charging.
Suppose you only have a single EV charger that is shared between multiple EVs, and you’re regularly driving long distances each of them. In that case, a 3-phase charger might make it easier to limit EV charging to cheap off-peak periods for overnight charging.
Can I install a single-phase charger if I have a 3 phase supply?
Yes. Just like most other appliances in your home, your EV charger will connect to one of the 3 supply phases.
Can I use a single-phase EV charger with a 3 phase solar system?
Yes. Charge HQ automatically takes into account solar production across all three phases when charging from excess solar. Your EV will use the solar from the phase it’s connected to and perhaps some grid energy, there may be exports on the other two phases whilst you are charging. But, your energy meter considers the production and consumption across all 3 phases in real-time. Charging on a single phase or 3 phase will have no effect on your energy bill with a 3 phase solar system.
If I have two or more EV chargers can they be single-phase?
For homes with a single-phase grid connection - you can still have two or more single-phase EV chargers. You will need to check the capacity of your grid connection and may require dynamic load balancing to run two chargers at 7 kW. Your electrician will be able to offer guidance.
For homes with a 3-phase grid connection - you can install 2 x single-phase chargers, depending on the electrical loads from other home appliances, each charger is likely to be installed on a separate phase. Your electrician will be able to offer guidance.
