3 Phase Powerwall

[arnyswart]

Hi

I have a powerwall which was set up for one phase with the original gateway.

My house is now three phase but the powerwall only reads one phase. I called Tesla and they said it can use CTs to read the other phases. They said it can do this with wired and wireless ones.

However, I cannot find an electrician who can see how to fix.

So I have 6.6 kw of solar that the powerwall does not register is being produced.

Any ideas?

 

[paulp]

You need to find an electrician experienced at installing powerwall. There is programming that has to occur when the ct’s are added.
In any case I dont think the original gateway works with 3 phase. Someone else on here may know.

 

[Vostok]

You need to find an electrician experienced at installing powerwall. There is programming that has to occur when the ct’s are added.
In any case I dont think the original gateway works with 3 phase. Someone else on here may know.

The original gateway is 1-phase only but in a 3-phase house CTs are on all 3-phases so that the PW2 and gateway knows what the total house load is and, if it can, nets out total house consumption by exporting on Phase A sufficient power (from solar &/or battery) to offset consumption on Phases B and C so that from an electricity bill perspective you are getting full value out of your solar plus battery. That’s the way mine works.

So, yeah, you need to find an electrician who has installed powerwalls - maybe ask a solar installer to recommend someone.

 

[Onshore]

Is it an option to contact the firm that originally installed the whole setup?

 

[paulp]

The original gateway is 1-phase only but in a 3-phase house CTs are on all 3-phases so that the PW2 and gateway knows what the total house load is and, if it can, nets out total house consumption by exporting on Phase A sufficient power (from solar &/or battery) to offset consumption on Phases B and C so that from an electricity bill perspective you are getting full value out of your solar plus battery. That’s the way mine works.

So, yeah, you need to find an electrician who has installed powerwalls - maybe ask a solar installer to recommend someone.

Yes but the install is a powerwall 1 so is their any point if it only does single phase?

 

[Vostok]

Yes but the install is a powerwall 1 so is their any point if it only does single phase?

Yes. Consider this situation with a 1-phase solar inverter and Gateway (which is what I have):

• Solar generation: 2 kW
• PW2 Battery: 100%
• Phase A load: 1 kW
• Phase B load: 2 kW
• Phase C load: 3 kW

If the PW2 gateway is configured to only measure Phase A, the power flows would be:

• Solar to Phase A load: 1 kW
• Solar export on Phase A: 1 kW
• Battery export on Phase A: 0 kW
• Grid metering on Phase A: -1 kW
• Grid metering on Phase B: 2 kW
• Grid metering on Phase C: 3 kW
• Net grid metering: 4 kW
• Battery stays at 100%

If the PW2 gateway is configured to measure all 3 phases, the power flows would be:

• Solar to Phase A load: 1 kW
• Solar export on Phase A: 1 kW
• Battery export on Phase A: 4 kW
• Grid metering on Phase A: -5 kW
• Grid metering on Phase B: 2 kW
• Grid metering on Phase C: 3 kW
• Net grid metering: 0 kW
• Battery is discharging

So in the first situation, only Phase A is being netted out and the customer is paying for 4 kW of grid electricity despite the battery being full.

In the second situation, even though export is only happening on Phase A, the customer is paying zero for grid electricity.

 

[paulp]

Yes. Consider this situation with a 1-phase solar inverter and Gateway (which is what I have):

• Solar generation: 2 kW
• PW2 Battery: 100%
• Phase A load: 1 kW
• Phase B load: 2 kW
• Phase C load: 3 kW

If the PW2 gateway is configured to only measure Phase A, the power flows would be:

• Solar to Phase A load: 1 kW
• Solar export on Phase A: 1 kW
• Battery export on Phase A: 0 kW
• Grid metering on Phase A: -1 kW
• Grid metering on Phase B: 2 kW
• Grid metering on Phase C: 3 kW
• Net grid metering: 4 kW
• Battery stays at 100%

If the PW2 gateway is configured to measure all 3 phases, the power flows would be:

• Solar to Phase A load: 1 kW
• Solar export on Phase A: 1 kW
• Battery export on Phase A: 4 kW
• Grid metering on Phase A: -5 kW
• Grid metering on Phase B: 2 kW
• Grid metering on Phase C: 3 kW
• Net grid metering: 0 kW
• Battery is discharging

So in the first situation, only Phase A is being netted out and the customer is paying for 4 kW of grid electricity despite the battery being full.

In the second situation, even though export is only happening on Phase A, the customer is paying zero for grid electricity.

Yes but the discussion is around PW1 gateway not PW2 gateway. They are very different to each other.

 

[Vostok]

Yes but the discussion is around PW1 gateway not PW2 gateway. They are very different to each other.

Where does the OP say it is PW1? Where they say “original Gateway” I assume the reference is to the grey box one, which is what I have, not the newer sleeker white Tesla branded box. Perhaps @arnyswart can clarify.

 

[WoodWombat]

Yes but the discussion is around PW1 gateway not PW2 gateway. They are very different to each other.

Powerwall 1 was mostly DC Coupled and used special external inverter chargers. Powerwall 2 is AC coupled and the way that he describes it is exactly how my 3 phase setup works so I really think that it is more likely a PW2 here, especially since I don't think that there are many PW1s in Australia at all.

Back to the issue at hand, I agree with what @Vostok says here, since that is exactly how mine works.

I just wish that Tesla would make a three phase gateway. I originally ordered 3 but eventually gave up and just installed a single unit in 2017 which has worked flawlessly every since, but would much rather have had the option to keep the original phase balancing I had in my house.

 

[arnyswart]

Where does the OP say it is PW1? Where they say “original Gateway” I assume the reference is to the grey box one, which is what I have, not the newer sleeker white Tesla branded box. Perhaps @arnyswart can clarify.

Yes. Powerwall 2, grey box gateway.

 

[ringsau]

Hello,

I have a 10kw SolarEdge PV system with a 3-phase inverter on our 3-phase home in the ACT. I just had a Powerwall installed by a Tesla accredited installer. The Powerwall plays nicely with the 3-phase system and I can see masses of real-time info on solar production, battery charge/discharge, grid import/export etc in the Tesla app.

It is very impressive indeed and our use of peak tariff electricity (7-9 am and 5-8 pm) has dropped to zero. Powerwall supplies all our energy needs during those 7 hours per day either by solar (on sunny days) or off-peak load shift (on cloudy/rainy days).

 

[skyworxx]

@ringsau Would you mind sharing a bit more info on the install? I am in the same situation (minus powerwall) and am thinking of installing one. As I understand it, you have to decide which phase of the house to connect to the powerwall?

 

[lazjen]

I've got 3 phase + Powerwall, put in April 2021. Yes, you have to pick a phase for the PW, and what you want to have connected to that phase.

 

[skyworxx]

Would that still work for 3 phase appliances such as ducted heating/cooling? I guess it'll just draw one third from the battery, two third from the grid?

 

[Vostok]

Would that still work for 3 phase appliances such as ducted heating/cooling? I guess it'll just draw one third from the battery, two third from the grid?

Yes that is how it works, provided the grid is up. 3-phase ducted airconditioners are usually massive power hogs, and will suck the full 5 kW from your PW2 in an attempt to offset their total consumption (which is usually between 5 and 10 kW depending on the size of the system), thereby fully draining your battery in a little over 2 hours.

If the grid goes down, 3-phase appliances won’t work, even though Phase A (or whichever phase your PW2 is connected to) is still live. I have been told the Tesla HPWC wired up as 3-phase will still work if only 1 phase is active but I’ve not tested it.

 

[Stuart Thomson]

Yes, I suspect that this is what's happening at my place. I have a three phase HVAC system at about 7.5kW. The powewall cannot net meter the power consumption out. If the HVAC is operating and drawing 7.5 kW the PW can only supply 5 kW at max. What I'd like to know is if the home is using 1 kW as well, mostly on the same phase as the PW backup (lights etc), I'm assuming the PW could only net out 1.5 kW? How does this work? Am I drawing 2.5 kW on the other two phases and then exporting 1.5 kW on the third phase?

What are my options for a system like this, I have spoken to Origin Solar about two more PWs but they told me it wouldn't work. Can you run three gateways and phase lock them 120 deg apart? Mr Powercor said that this wasn't possible as it would result in an unacceptable phase imbalance, but I think that he has a vested interest in me buying power!

Cheers
Stu

 

[Vostok]

I have a three phase HVAC system at about 7.5kW. The powewall cannot net meter the power consumption out. If the HVAC is operating and drawing 7.5 kW the PW can only supply 5 kW at max. What I'd like to know is if the home is using 1 kW as well, mostly on the same phase as the PW backup (lights etc), I'm assuming the PW could only net out 1.5 kW? How does this work? Am I drawing 2.5 kW on the other two phases and then exporting 1.5 kW on the third phase?

See my August 9 post above. The system will attempt to export enough power on Phase A (the backed-up phase) to offset total household grid consumption, up to a maximum of 5 kW. It doesn’t matter how that consumption is distributed across the phases.

If your AC is using 2.5 kW per phase, plus house 1 kW on Phase A, and there’s no solar (e.g. nighttime) then the PW2 will be sending 3.5 kW to the house on Phase A (your actual consumption), 1.5 kW export to the grid on Phase A (what’s left over), and phases B and C are using 2.5 kW each.

So your house is using a net of 3.5 kW of grid power across all 3 phases (2.5+2.5-1.5). Which is your total consumption (8.5 kW) minus the 5 kW capacity of the PW2. The Tesla App won’t show power being exported on Phase A, it will just show your house using 8.5 kW of which 5 kW is coming from PW2 and 3.5 kW from the grid.

 

[Vostok]

What are my options for a system like this, I have spoken to Origin Solar about two more PWs but they told me it wouldn't work. Can you run three gateways and phase lock them 120 deg apart? Mr Powercor said that this wasn't possible as it would result in an unacceptable phase imbalance, but I think that he has a vested interest in me buying power!

I believe that is right. 3xPW cannot be configured to fully back up a 3-phase house and go off-grid. It just adds more capacity to the backed-up phase.

On a 3-phase house, the “go off-grid” command in the App doesn’t actually take you off grid. Phase A will be disconnected, but not phases B and C. If Phase A is using more than 5 kW it won’t disconnect and I think you get a warning to reduce consumption. If the grid really was down, PW2 would shut down if you try to pull more than 5 kW out of it except for very brief periods.

When I really did have a grid outage once, only lights and power on Phase A still worked, and the gateway controlled the solar inverter to track the Phase A load exactly, since it was no longer possible to export any power (PW2 was full). If solar production ever dipped below load, PW2 made up the difference.

 

[technerdx6000]

Theoretically, 3xPW2 should be able to back up a 3 phase house, except for 3 phase loads. There is no reason why you couldn't connect a powerwall and gateway to each phase separately.

There are drawbacks however. Each powerwall would drain individually as they have no idea the other powerwalls are present. So if phase 1 has all your cooking appliances on it, the powerwall connected to phase 1 will drain faster than 2 and 3 in the evenings.

You would need to monitor your phase loads individually and get an electrician to shift your loads so over 24hrs each phase has an equal total energy draw.

Also, when the grid is down, 3 phase loads won't work (and could cause major issues) as the powerwalls will not keep the 120 degree phase separation. Single phase loads won't care however, so essentially your house would have to be configured to run as 3 independent single phases when the power is out. I imagine relays could be used to cut power to any 3 phase loads during an outage by looking for power on the grid side of the PW gateways.

To be tricky, you could look into using a frequency/function generator to trick the powerwalls when the grid is down into keeping 120 degrees phase separation, but thats a bit more complicated.

Disclaimer, I'm no electrician

 

[GrimRe]

Hopefully the rumoured LFP based PW3 will have a 3-phase built-in hybrid inverter.

You should be able to hook up 2x MPPTs, 3-phase grid tie, 3-pole switchboard breaker all in the one unit. Then when you go off-grid your entire switchboard is an island energized by the solar and battery. would make installation more simple and allow for proper grid stabilization whereby grid operator can remotely command PW3 to stop exporting solar or start exporting battery power during extreme events.