EV Chargers: Single-Phase Vs. Three-Phase

SolarQuotes founder Finn Peacock answers a common electric car charging question: single-phase vs. three-phase chargers – which are better?

— Transcript begins

When it comes to EVs, one question that comes up all the time on email and on our socials (which we’d love you to subscribe to by the way1) is:

“Should I go for three-phase; or is a single-phase enough to charge an electric car?”

Well, that’s a great question. Let’s go through the basics of electric car charging in your home.

EV Charging From A Wall Socket

Your first option, which is good enough for some people all the time, is you simply plug your car into a regular socket. A regular socket can give you 10 amps.10 amps times 230 volts gives you 2.3 kilowatts. So, you can charge at just over two kilowatts from a standard socket using the wall box that came with your car.

Now, if you’ve got a 60 kilowatt-hour battery, that’s going to take about 30 hours to charge from empty. So it is a slow trickle charge, but if you don’t empty your tank every day, then that doesn’t matter. If you only use 10 kilowatt hours on a typical day, then you plug it in for five hours overnight; boom, you’ve got a full battery.

So, a standard socket will charge at just over two kilowatts. But if you want to buy a dedicated charger that goes on the wall, your options are single-phase or three-phase. And the question is, what should they go for? Well, let’s go through the pros and cons of each.

Single-Phase Dedicated EV Charger

If you get a single-phase dedicated charger, that’s a 32-amp circuit. 32 amps times 230 volts is about seven kilowatts. You could charge at about seven kilowatts. That’s a really nice feed to charge your car at, because if you’ve got a 60 kilowatt-hour, 70 kilowatt-hour battery, you’ll easily charge it overnight.

So you might be thinking, okay, well, seven kilowatts. That’s all I need. I can charge my car from empty overnight.

Three-Phase Dedicated EV Charger

But if you get three-phase, you can charge potentially three times faster, up to 21 kilowatts. But be careful; your car might not charge at 21 kilowatts from an AC supply. Check the specs of your car.

So, you can charge up to 21 kilowatts. Up to three times faster.

When would you want to do that? Well, if you’re in a hurry, you’ve drained your battery and you need to go on a long trip and you need to go soon. You’ve got the flexibility there to charge three times faster.

You can fill your 60 kilowatt-hour battery in about three hours. So, that’s really nice. The other thing that’s nice about high power charging from three-phase is it makes it easier to maximize your solar. If you’ve got more than seven kilowatts of spare solar power capacity, you can bang that into your car if you’ve got a three-phase connection to your car charger.

Now, the other reason that you might want three-phase is looking a bit further into the future. The average household in Australia has more than one car and all your cars – very soon, trust me – are going to be electric. So, if you’ve got two cars in the garage and you want to charge them both overnight, you want more than single phase because you might want to charge them both at seven kilowatts.

My advice, if you’re building a house or you’re running a wire from your switchboard to your garage for an EV charger, run three-phase. Three-phase cables aren’t that much more than single-phase cables when you take into account the cost of the labour.

The expensive bit’s the labour, putting the cable in. If you’re going to put a cable in, you might as well put three-phase in, even if you don’t use it initially. You will thank me when you get more than one EV.

— Transcript ends

For further information on EV charging and electric cars generally, check out Episode 10 of SolarQuotes TV: The Ultimate Guide To Electric Vehicles. For more SQTV episodes and videos on everything solar energy-related, visit and subscribe to the SolarQuotes Youtube channel.

Related: The SolarQuotes Home Owner’s Guide To Solar And Electric Cars.

Footnotes

  1. SolarQuotes on social media: Youtube | Facebook | Twitter | Instagram | LinkedIn | TikTok
About Michael Bloch

Michael caught the solar power bug after purchasing components to cobble together a small off-grid PV system in 2008. He's been reporting on Australian and international solar energy news ever since.

Comments

  1. Richard Kirby says

    So simple and very helpful!

  2. I wonder how difficult it is to upgrade your home from single to three phase?

    Most homes i imagine only have two wires in the conduit from the street point. In my case that conduit changes direction several times in the the run underground over about 25-30 meters.

    Is it actually feasible to upgrade in this case to 3 phase in existing conduit? Ie without digging a new trench.

    • Jim Haseldine says

      3 phase has to be run from the street, provided it is available in your street.. I had to run 3 phase to my workshop to operate lathe and welders and had to run a new feed from the street, luckily it was available in my street, light industrial zone.I needed a separate meter and all for 3 phase.

      • Jim, I know it runs from the street.

        The question is, how feasible is it to add later when the feed to the house is by under gound wires.

        The conduit in my place for example is quite small, and I don’t know if they can actually pull wires thru for 3 phase or do they have to dig up the front yard and run new conduit. Not easy in my case and many others as there will be concrete paths, possibly walls or fences over the conduit.
        If it does have to be re-laid then it’s going to be pretty expensive to run plus restore the grounds to as before status.

        • Geoff Miell says

          Glenn P,
          The question is, how feasible is it to add later when the feed to the house is by under gound wires.

          Ask the sparky to check how many conductors you have already in your underground supply conduit, if/when you request a quote to upgrade your supply to 3-phase. If you have a 4-core cable installed, but only some of those conductors currently used, and there’s spare space for 3-phase expansion in the meter box then it’s relatively easy-peasy. If not, not so easy.

          The document titled Service and Installation Rules of New South Wales: The electricity industry standard of best practice for customer connection services and installations, amended 30 Jun 2015, includes Chapter 2 for underground services, that may be informative.
          https://neca.asn.au/sites/default/files/media/state_nsw/Media/SIR%20June%202015%20Final.pdf

  3. Not enough information in your question to provide an answer. It really depends on the size of the conduit that the first sparky put in and the size of your consumer mains. As a rough rule of thumb, if the conduit is 40mm or larger, you might be able to pull through a three phase cable. However, the direction changes might make this hard to do.

    • Thanks, I doubt the conduit is 40mm or larger. I imagine they just put in what size conduit carries the 2 single phase wires only.

      My run has several near 90deg bends also so pulling wires thru maybe difficult. Sounds like it would be pretty expensive to go to 3 phase.

  4. I really wanted 3 Phase for a new build, but alas, the street wasnt accomodating me 🙁

    Looks like I can top out my solar system at around 10Kw, so when its time to get an electric car, looks like im in for the overnight trickle charge.

  5. Missing key information. Who is our first point of contact to try and upgrade to 3 Phase electricity for our home?

  6. If a house has a single phase from the grid, can you install three phase between other components without upgrading the grid connection to three phase too (e.g. only the EV charging point, switchboard, battery, solar inverter)? Or do you need to upgrade the whole house?

  7. What sort of a cost would we be looking at to get 3-phase into our rural street. I believe there is 3 phase about 1 km away. Any thoughts?

  8. As an electrical engineer from the electricity industry, I recommend anyone contemplating a three phase supply for battery charging should ask a qualified electrician for advice.
    As some guidance, a 30amp supply is equivalent to an electric stove. Therefore some houses will need an upgrade to their main supply cable from the street even for a single phase battery charger.
    For most urban settings, a three phase battery charger will need a significant upgrade to their meter and switchboard, and as one letter writer has mentioned – the nearest street 3 phase supply can be a block or three away.
    In some cases, a 3 phase supply to your house will require a new transformer, and perhaps an upgrade of the local High Voltage mains from single phase (2 wires) to 3 phase (3 wires).Cost between $50K and $250K.

    The issue of battery charging overnight, or even during the day excludes solar panels because even on a good day, 10 panels can only deliver about 3kW, and for only about 6hours per day because the sun’s angle to the panels early morning and late afternoon does not deliver much energy.

    By comparison, the “fast-chargers” being given a lot of media time recently require about 200-300kW each (equivalent to 20-30 houses). That kind of new electrical load usually requires a new substation and often new underground HV cables. Cost $0.5-1.0M for 2 or 3 fast-charge points.
    But if we think of the cost of setting up a new petrol station with 4 petrol bowsers, then $1M is not outrageous. But we will need to charge the equivalent of petrol tax in some way – 40c/kWh not 25c/kWh.

    Interesting times ahead.

    • The requirements for 30 houses work of energy per fast EV charger is why EVs are overrated. Where is the infrastructure to enable this??

      Since the average daily commute is under 50 kms, PHEVs make perfect sense.

      (Disclaimer, I own one.)

      With lithium being a precious resource why make just 1 x 500 kms range EV when you can make 10 x 50 kms range PHEVs with that same amount of lithium?

      PHEVs get fully charged overnight off a standard single phase 10 amp wall outlet in your garage.

      Immediate zero CO2 for the daily commute, and, being a hybrid of sorts, even the occasional 1,000 kms special journey uses just 6.9 L/100 kms of E10 (as used by my 1,800 kg SUV).

      An EV with zero range anxiety – and no need for a taxpayer funded expensive Roadside Charger at the back of Burke, used by maybe a handful of vehicles each year.

      PHEV, the smart way to zero CO2 emissions.

      Do the math!

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