3 phase charger with 1-phase solar

[-Dave]

Hi folks. Recently pulled the trigger on a model 3 and trying to sort out my home charging situation as I believe they no longer come with a mobile connector.

I have an existing solar+battery (PW2) setup currently running on 1-phase.

I'm looking to upgrade my house to a 3-phase mains connection so I can maximise charging speed if I need it.

So here's my question: can I use ChargeHQ to charge from just excess solar (which is all one 1 phase) using the 3 phase wall connector?

But then if I need a faster charge, switch to 3-phase charging from the grid?

 

[RichardV]

Hi folks. Recently pulled the trigger on a model 3 and trying to sort out my home charging situation as I believe they no longer come with a mobile connector.

I have an existing solar+battery (PW2) setup currently running on 1-phase.

I'm looking to upgrade my house to a 3-phase mains connection so I can maximise charging speed if I need it.

So here's my question: can I use ChargeHQ to charge from just excess solar (which is all one 1 phase) using the 3 phase wall connector?

But then if I need a faster charge, switch to 3-phase charging from the grid?

https://support.solarquotes.com.au/hc/en-us/articles/6030114486799-How-do-3-phase-meters-work-with-single-phase-solar-

If you do upgrade to 3-phase you should not need to, nor is it desirable from a grid perspective, to run your EV charger as single phase.
Charge HQ should be able to work this out for you and if like in the example linked above you have 6kW of solar and Charge HQ is set to track solar and the only thing running is your charger then electrically you will export 4kW on one phase and import 2kW each on the other two phases but you will have 0kW applied from a billing perspective.

Having said that you might want to reconsider the expense of installing a 3 phase meter, if you need to bring in 3 phase from the street even more so, as the difference in charging is between 7kW single phase and 11kW three phase. Note that you don't get three times the power increase in going from single phase to three phase as the Tesla on board charger does some clever re-arranging via relays to give you effectively two units of charging of off the single phase connection. Basically the Tesla has three on-board 3.7kW charging units, single phase will use two of these units in series for 7kw / 32A charging and three phase will give you 3 units in parrallel for 11kW / 3x16A charging. (In the US you can get 11kW / 48A single phase charging by combining all three but I do not think that configuration is available here).

 

[-Dave]

Thanks for the detailed reply RichardV.

electrically you will export 4kW on one phase and import 2kW each on the other two phases but you will have 0kW applied from a billing perspective.

Thanks. I wasn't aware the 3-phase meter did this. Good to know.

you might want to reconsider the expense of installing a 3 phase meter, if you need to bring in 3 phase from the street even more so

Need to upgrade the consumer mains anyway as it's a piddly little 6mm2 cable and I want to disconnect gas and electrify the entire house eventually. Figure I might as well bring in 3-phase and future proof things as much as possible.

 

[RichardV]

Thanks for the detailed reply RichardV.

Thanks. I wasn't aware the 3-phase meter did this. Good to know.


Need to upgrade the consumer mains anyway as it's a piddly little 6mm2 cable and I want to disconnect gas and electrify the entire house eventually. Figure I might as well bring in 3-phase and future proof things as much as possible.

Right, there may be other reasons for 3-phase. I am about to install 3-phase to go beyond the 6.6kW solar system limit in my area.

 

[Vostok]

Note @-Dave that if you get 3-phase and later get a PW2 battery (or any other battery for that matter) only 1 phase of your house will be backed up. To my knowledge, there are no 3-phase battery solutions out there. Even if money was no object and you bought 3 PW2s, my understanding is it is still not possible for them to be configured to back up a 3-phase house (I’m sure I’ll be corrected if that is not right ) because they can’t be wired up to operate 120° out of phase with each other.

This is important to know because when you get your house upgraded to 3-phase power, that is the time at which you need to decide which bits of the house (power and lighting) will be connected to Phase A and which bits get connected to Phases B and C. Because you will want the most important bits on Phase A so that in the future that can be backed up with a battery.

My house was 3-phase when I bought it, but last year I got a sparky in to rearrange the phases to optimise what is backed up. Basically, all downstairs lighting, fridge, kitchen benchtop sockets, instant gas hot water, internet, lounge room and garage door will stay on under a grid outage. Things like the oven, spa bath, EV charging, air conditioning and upstairs power and lighting is not backed up.

 

[RichardV]

To my knowledge, there are no 3-phase battery solutions out there.

A three phase hybrid inverter with a DC battery attached. Solar is technically optional but this type of situation makes more sense when adding 3 phase solar and a having 3 phase battery via the same inverter.
A single phase battery on one phase is not such a big issue in a 3 phase house. Similar to how it is described above the battery in this case will export on one phase and you will draw from the grid on the other 2 but the net instantaneous metering means you will not pay for the grid usage, it will be wholly cancelled out by your battery export. For backup you are unlikely to be able or desirable to back all phases up. So setting up the devices to backup onto a single phase and circuit which contains the battery should not be too onerous.

 

[Borgy]

Need to upgrade the consumer mains anyway as it's a piddly little 6mm2 cable and I want to disconnect gas and electrify the entire house eventually. Figure I might as well bring in 3-phase and future proof things as much as possible.

Mine was 6mm2 but the cable attached to the house was already 25mm Aluminum already so just got my mains from the point of attachment to the meterbox updated to 16mm2, it may be a cheaper route and will give you 7kw charging no issues.

Going 3 phase may not be worth the extra costs

 

[Chuq]

If you are going 3-phase for other reasons, ignore my comment.

But if you're doing it purely for EV charging, don't. Totally not needed. For a Model 3/Y, it's only 1.5 times what a single phase, 7 kW charger will do, which is 50 km of range per hour.

You will just be topping up each night or every few nights, and a 7 kW charger will do this comfortably. You'd need to have a very specific/unusual driving pattern to need 3-phase.

 

[-Dave]

Thanks for the replies everyone.

Yeah I understand the benefits for EV charging are marginal. but the actual cable coming in from the pole on the street is 6mm2. It's probably only good for 7-8kW total so it needs replacing regardless.

What's more, the old cable cuts across the corner of my neighbour's property, so I'm told the new connection will have to go underground. If I'm going to that much trouble, I might as well pull in a 3-phase cable.

 

[paulp]

Note @-Dave that if you get 3-phase and later get a PW2 battery (or any other battery for that matter) only 1 phase of your house will be backed up. To my knowledge, there are no 3-phase battery solutions out there. Even if money was no object and you bought 3 PW2s, my understanding is it is still not possible for them to be configured to back up a 3-phase house (I’m sure I’ll be corrected if that is not right ) because they can’t be wired up to operate 120° out of phase with each other.

This is important to know because when you get your house upgraded to 3-phase power, that is the time at which you need to decide which bits of the house (power and lighting) will be connected to Phase A and which bits get connected to Phases B and C. Because you will want the most important bits on Phase A so that in the future that can be backed up with a battery.

My house was 3-phase when I bought it, but last year I got a sparky in to rearrange the phases to optimise what is backed up. Basically, all downstairs lighting, fridge, kitchen benchtop sockets, instant gas hot water, internet, lounge room and garage door will stay on under a grid outage. Things like the oven, spa bath, EV charging, air conditioning and upstairs power and lighting is not backed up.

I have 3 PW2 and 3 phase and confirm that only one phase works in a blackout. Not really an issue as I configured the circuits with essentials on that phase.

 

[Goanna]

It's easy to get carried away thinking you need to have to spend money and get a charging solution put in. I was thinking that, but being lazy just waited. With a UMC cable to can plug into a normal 10A outlet, and unless you are driving a lot you should be fine! Plug it in in the evening, and you should be able to go from 50% to full overnight. Or for a bit extra get a 15A socket put in. Then see how you go. I've had my Y for 3 months and I have no trouble keeping it charged, usually using the 10A, though I do also have a 15A in the shed, I just need to get out an extension cable to use that.

 

[cafz]

It's easy to get carried away thinking you need to have to spend money and get a charging solution put in. I was thinking that, but being lazy just waited. With a UMC cable to can plug into a normal 10A outlet, and unless you are driving a lot you should be fine! Plug it in in the evening, and you should be able to go from 50% to full overnight. Or for a bit extra get a 15A socket put in. Then see how you go. I've had my Y for 3 months and I have no trouble keeping it charged, usually using the 10A, though I do also have a 15A in the shed, I just need to get out an extension cable to use that.

It depends on how much faith you have in the existing wiring and outlets, too.

Personally I didn't really trust the old wiring and outlet in the garage to handle 10A continuous for 12 hours at a time, so wanted a new dedicated circuit put in. At that point, once I was paying for those materials and labour, I might as well put a HPWC on the end of it.

 

[Gareth Oakes]

To my knowledge, there are no 3-phase battery solutions out there.

They're commercially available today. We have a Redback ST10000 that does 3 phase solar and battery, including backup power.

 

[tragic]

They're commercially available today. We have a Redback ST10000 that does 3 phase solar and battery, including backup power.

Agree. Commissioned a 3 phase Fronius with BYD batteries and new panels a few months back. House already 3 phase with 3 phase wall charger. All relatively seamless including backup power to all circuits. So definitely possible. Kept the old single phase solar system running as bonus.

 

[-Dave]

Does anyone use Amber Energy (or similar) wholesale pricing to reduce (or reverse) their charging costs?

Daytime wholesale prices are often negative all summer long here in SA so I'm hoping to get paid to charge the car. It's another reason to go for the 3-phase charger to make the most of negative prices.