[EU] Powerwall and 3-phase 400VAC

[lorn10]

This is really a super interesting topic, - many thanks to all for these information.

I can now add here a further little "rumor". Regarding the Swiss market there could exist the possibility that Tesla will introduce in conjunction with it's Tesla Solar Roof also the DC version of the Powerwall 2. So that config would be also capable to deliver 3-phase power.

This has told me (informally, after intensive requesting) the main countrywide Powerwall 1 Tesla distribution partner. It may be just an assumption, however it could also become fact. Whatever, - we will see it in 2019 with the introduction of the Tesla Roof products in Switzerland.

As mentioned, that speculation is currently only Swiss-related because we have here regarding single phase house batteries a low limit of only 3,6 kW AC output. (!) So to fulfill this regulatory limit, - every Powerwall 2 AC must be limited in Switzerland by firmware / software. I know, that's not easy to understand....

Finally it could be also possible that Tesla will introduce in whole Europe the DC PW2 version, but only bundled with it's Tesla Solar Roof products. Such an solution will then also contains most likely a Tesla made inverter.

 

[jmorrison]

It's hard for me to imagine any home or business that had 3-phase service and no 3-phase loads. Provisioning a system for three phase power that does not guarantee that the three phases maintain the correct phase relationship is nonsense.

That's what the neutral is for.

It's up to electricians to distribute loads across the phases.

In North America, 3phase 120/208 is common in multi-tenant residential and commercial.

Three apartments/condominiums: each unit would have a standard residential breaker panel
Unit 1: phase A, B = 120/208 - 120V for branch/lighting circuits, 208V for electric heat, dryer, stove, possibly hot water
unit 2: phase B, C
unit 3: phase A, C

- few or no 3phase loads in a small walk up apartment building
- motels: PTAC air-conditiong/heat pump units 208V - also not 3 phase

commercial: three phase breaker panel or sub:
single phase breakers to 120V loads
two phase circuit breakers to 208V loads - very common in data centers
three phase: motor loads like elevators/escaltors, large central hvac

 

[miimura]

That's what the neutral is for.

It's up to electricians to distribute loads across the phases.

In North America, 3phase 120/208 is common in multi-tenant residential and commercial.

Three apartments/condominiums: each unit would have a standard residential breaker panel
Unit 1: phase A, B = 120/208 - 120V for branch/lighting circuits, 208V for electric heat, dryer, stove, possibly hot water
unit 2: phase B, C
unit 3: phase A, C

- few or no 3phase loads in a small walk up apartment building
- motels: PTAC air-conditiong/heat pump units 208V - also not 3 phase

commercial: three phase breaker panel or sub:
single phase breakers to 120V loads
two phase circuit breakers to 208V loads - very common in data centers
three phase: motor loads like elevators/escaltors, large central hvac

My point stands.

In the apartment/condo scenario the fact that the distribution is 3-phase is incidental to the end user. Their meter and breaker panel is only 2-phase, so they don't have 3-phase service. Obviously a hotel is metered in total with 3-phase service, but I'm still willing to bet common areas, kitchens, etc. have larger loads with actual 3-phase loads.

The commercial case you presented actually reinforces my point. They have 3-phase service and they have 3-phase loads for A/C, pumps, elevators, etc. Therefore, any backup power must have proper in-phase 3-phase output.

Besides, this is an EU thread and they use 230Y/400V

 

[WannabeOwner]

Three apartments/condominiums: each unit would have a standard residential breaker panel

Just for info;

Here in the UK single-phase to Residential is the norm.

At work (office is in a small village) we have 3-Phase. When one of the phases drops out <sigh> every third house in the street loses power and of course 1/3rd of the office rooms in our building.

We don't have (and have no need of) any 3-phase circuits in the building, other than perhaps Tesla charger, but that happily charges during the normal working day on single-phase (8 hours = 170 miles added), so don't really need that either.

Only usage I know of where folk have installed Residential 3-Phase (at HUGE cost - £xx,xxx not uncommon here in UK as Power company has monopoly over the install) is for air-source heat-pump for winter central-heating, or summer pool heating (and solar thermal better for that ... we only heat our pool to get it up to temperature at the start of the season, and maybe for a few weeks at the end, the rest of the time solar thermal is 95+% good enough; our boiler heats accumulator which allows heat to be shared between winter house heating and pool heating)

 

[lorn10]

Okay folks, - I can confirm for Switzerland that near every more recent house or building has definitively a 3-phase service available "to the end-customer". It is used usually for devices with heavy power consumption like an oven. A normal one-family house has usually also one 400V/16A CEE plug available, that one can be found mostly in the garage. Furthermore our alpha innotec SW 232H3 (23kw) heat pump needs 3-phase power.

Larger block of houses may have big 3-phase washing machines. Some whirlpools seems to be also 3-phase capable.

There exist out of mine view NO huge cost factor regarding a 3-phase service, - such a fact may be UK related. I also cannot confirm here any special problems regarding our 3-phase power service, - also this may be UK related. As mentioned, 3-phase services are standard in most Central European countries, - you pay usually the electricity and NOT any 3-phase topology.

So, I do not see any drawback, - regarding the electric car future it has out of mine view only positive aspects. A single phase 120V service would be for me a total nightmare.

To conclude, - every one (in Europe) which is able to buy a Tesla car should be also able to pay for a 3-phase service at home.

 

[widodh]

The UK is different since it has it’s own grid and is DC-coupled with the European grid.

The rest of Europe is all 400VAC 3-phase and usually into the residence.

Yes, there are some pockets with very old grids left, but anything modern in Europe is 400VAC.

I travel through Europe very often and always find those red 400V 3-phase CEE connectors.

Now get me my 3-phase Powerwall

 

[JohnWD]

We’re building a new house in the U.K. There will be approx 8kWp PV on the roof. In the U.K. as I understand it, in excess of 4kWp PV generation needs to go 3-phase to balance the loadings on the phases. We are therefore having 3-phase supply there for the PV and for EV charging in due course, but contrary to what has been said by WannabeOwner this isn’t necessarily very expensive to do this. We already have 3P installed to the garden shed which is the temporary meter location during building works. We had 3-phase in our previous house due to the electric storage heating load at the end of a supply route. So when we installed 7kw PV there we used multi-phase.
My interest here is in the use of an AC PW2 on one phase but effectively working from a metering and in-house PV consumption maximisation point of view, across the 3-phases. I have tried to get a technical write up from Tesla about how this works and is cabled but without success although they did acknowledge that such documentation is needed! Has anyone managed to get hold of a technical manual describing this kind of installation? Ie like that described by smithy2167 on the first page of this thread?

 

[Tozz]

Our power supply companies use net meters that sum the consumption/feed-in from all 3 phases and only charge for the net total. So, if say one phase is drawing 2kW, another phase 3kW and the 3rd phase with the PW2 is feeding back 4kW, the net consumption that would be charged is 1kW.

Just as a note to others: In The Netherlands this is done the same way.

 

[Tozz]

So you have a 3 phase electrical supply at your house, and that is a common arrangement in the Netherlands?

It is.

That supply would support loads that are 230V single phase (line to neutral), 400V single phase (line to line) or 400V 3 phase. Are all of your household loads 230V single phase, or are there common loads that operate on 400V single phase or 3 phase?

Household loads are 230V single phase (16A breaker). However, there are appliances that use 3 phase, 400V such as:

- Induction cooking 'plates' (or whatever you call them)
- Heatpumps (getting more and more common, because we want to get rid of natural gas heating)
- EV chargers
- In older houses: Electric boilers, especially older public housing that do not have central heating). This is getting less common.
- Larger PV installations (that dont fit 16A 230V 1-phase)

 

[Tozz]

It however seems that all solutions for the Powerwall are 1-phase and in the Netherlands/Europe the whole grid is 3-phase 400VAC.

If your desire is to supply your power usage at night from the powerwall and don't really care about going off-grid a single phase powerwall could very well work. Because the meter sums up all phases to calculate actual usage, you could just supply the amount of watts used from all phases combined from the powerwall on a single phase.

So, eg:

L1-N: 100W
L2-N: 100W
L3-N: 100W

Electric meter would indicate: 300W usage

Now if your single phase powerwall would simply backfeed 300W, your electric meter would read: 0 Watts

In reality of course this would mean:

L1-N: -200W
L2-N: 100W
L3-N: 100W

But the electricity company would bill you for 0 watt.

 

[widodh]

If your desire is to supply your power usage at night from the powerwall and don't really care about going off-grid a single phase powerwall could very well work. Because the meter sums up all phases to calculate actual usage, you could just supply the amount of watts used from all phases combined from the powerwall on a single phase.

So, eg:

L1-N: 100W
L2-N: 100W
L3-N: 100W

Electric meter would indicate: 300W usage

Now if your single phase powerwall would simply backfeed 300W, your electric meter would read: 0 Watts

In reality of course this would mean:

L1-N: -200W
L2-N: 100W
L3-N: 100W

But the electricity company would bill you for 0 watt.

Yes, but I want true 3-phase as well. If the grid goes down I stay online

 

[DeeBee]

If your desire is to supply your power usage at night from the powerwall and don't really care about going off-grid a single phase powerwall could very well work. Because the meter sums up all phases to calculate actual usage, you could just supply the amount of watts used from all phases combined from the powerwall on a single phase.

So, eg:

L1-N: 100W
L2-N: 100W
L3-N: 100W

Electric meter would indicate: 300W usage

Now if your single phase powerwall would simply backfeed 300W, your electric meter would read: 0 Watts

In reality of course this would mean:

L1-N: -200W
L2-N: 100W
L3-N: 100W

But the electricity company would bill you for 0 watt.

I am note quite sure that this is the case, well at least not in the UK. Here we are billed on the peak phase at any point in time.

so for example

L1 - 100W
L2 - 200W
L3 - 100W

would be a billing value of 200W. This is one of the reasons that it is so important to keep the phases balanced. The per-KWh price for 3-phase is higher than single phase, although not 3x the price (in my experience). I do not know if this is the case in mainland Europe.

 

[Tozz]

Are you sure that 's how it is done? that would be stupid. Then you could use 6000W and only pay for 2000W. eg. you would use 2100W on L1, and 2000W on L2 and L3 and only pay for your usage on L1?

That doesn't make sense to me.

 

[cwied]

Not stupid at all if the rates are three times higher. You might be paying for 6000W when you're only using 2000W (if you're using 2000 on L1 and nothing on L2 and L3).

This arrangement seems like a way to charge both for usage and imbalance.

 

[Tozz]

Your example (about 2000w on L1 and 0 on l2 and l3) is about as wrong as my example is. Being that you get charged for something you do or don't actually use. It is just unfair.

Also, it wouldn't be rocket science to build a device that would divide your household load between 3-phases with a 5% offset to one phase, meaning 2/3 of your power consumption would be free.

I don't believe this is how it's done in the UK

 

[Tozz]

I've done some Googling on UK power networks, and it looks like they use kinda the same meters we use. I also read 3-phase household installations are nearly nonexistent in the UK. I also cannot find anything that says UK bills on "peak phase" instead of just the sum of the 3 phases + N.

 

[DeeBee]

As I recall it was down to the way that the power is generated via a giant 3-phase turbine. it was explained to me by our facilities manager when going through a phase balancing exercise. We paid about £0.35 per KWh when a retail power price was about £0.12-0.16, and I had to develop a monitoring system to identify the peak phase at any given time and record its value.

 

[DeeBee]

it seems I was wrong. Residential supplies measure the total usage over each phase.

IET Forums - Metering - 3 Phase

the datacentre I worked at did it the way I described, and that appears to be a special arrangement for larger supplies (ours was several MW)

 

[Tozz]

Glad we got that cleared up. It sounded really bizarre.

In a datacenter setup this would make somewhat more sense, but I still think its weird. The power company could simply have phase balance be a part of the contract, instead of resorting to weird billing tricks to get the customer to get his *sugar* together.

But again, since a datacenter would need all 3 phases anyway, billing peak phase * 3 seems like an approach that could work.

 

[widodh]

I gave Tesla a call again, but no information yet about 3-phase and the launch of the Powerwall in the Netherlands.

It got delayed again, so I will probably call again in 5 ~ 6 months and see how things work out then.