3-Phase Smart Meter Install - Tariff and Billing

Hi All,

I’m interested in having a 3-phase smart meter installed. I’ve read current status with installs but had two questions re tariff and billing for when the time comes if you can help? 

  1. If I’m on a competitive fixed tariff at the moment that’s due to end later this year, will having a new meter installed mean I’m moved onto a new tariff? I expect not but never done this before. 
  2. I have 3-phase supplied to my house but I actually only use a single phase at 100A. Does the way metering works mean I won’t see a change in energy consumption and cost because the smart meter effectively adds the use across the 3 phases? Ie 3000 kWh on one phase, but 0 kWh on the other two = billed for 3000kwh? Plus a single standing charge as it’s one meter? I have a 3-phase “heritage” meter at present

Im eager to have one fitted in order to access smart tariffs in future for EV charging. Rationale for having 3-phase smart meter fitted was to future-proof in the event I do utilise the other phases.

Thank you! 


Best answer by Blastoise186 12 March 2023, 22:52

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Userlevel 7
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Howdy @GettingThere !

Sure thing. I can answer these for you. :)

  1. Swapping the meter does not affect your tariff - you always remain on the same one you were on before unless the new meter is incompatible with that tariff (which is rare!).
  2. Yup! If your usage stays the same, so does the bill and one meter = one Standing Charge :)
    1. It’s a little complicated as to the number crunching, but the short version is that all three phases are added together and then combined to a single reading. So yes, P1 having 3,000 kWh + P2 having 100 kWh + P3 having 500 kWh = 3,600 kWh.
  3. I’ll ask the forum moderators to track your interest in an upgrade to Smart :)
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@Blastoise186 Jumping in on this, and having read some of your 3 phase replies from a year and more ago, does the summation of the phases include negatives, i.e. export? Do different meters do it differently?

My 3 phases are also unbalanced, with our house, solar, Power Wall and EV charger all on phase1. I have occasions in the summer months when I am importing from the grid on phase 2 (connected to outbuildings including pool pump and heater) and exporting on phase 1 (connected to solar and Powerwall). My current 3 phase Economy7 meter dials just tick up the difference if positive, and show nothing if negative.

Do 3 phase smart meters record energy importing separately from exporting? If so, I guess it's down to the provider whether they will do the subtraction sum before billing!

I had wished to remain with my current meter (I take daily readings and do a monthly YouTube report, so having to take readings myself is no problem!) but next year's planned turning off of the Radio TeleSwitch system has led me to start investigating where 3phase smart meters have got to.

Userlevel 2

Hey @ salokin welcome to the Forum!


That’s a great question on different phases and how that can relate to meter readings and exports. Whilst I do have a theory, I’m not entirely sure, but maybe @Blastoise186  can help us out?


You mentioned you do a monthly YouTube Report around your readings, would you mind telling us a bit more about that? It sounds like something we’d love to see, and I’m sure other community members would too! If you don’t mind sharing it with the community, please do. 😀


Hopefully Blastoise186 or another of our fantastic community can help us out with some answers to your questions.


Userlevel 7
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Sorry for the wait! I was a bit busy over the last few days - too many emails! :P

I can confirm that OVO is slowly rolling out Three-Phase Smart Meters. I’ve seen them in the Smart Meter Lab at OVO’s HQ for myself. They are capable of tracking Exports as well as Imports roughly in the same way as Single-Phase do.

In some cases it might be a little different though. If one phase (let’s say Phase A) is currently Exporting while Phases B and C are Importing, then what might happen is the Import Registers will spin for B and C while their Export Registers remain still. However, the Phase A Import Register will remain still while the Phase A Export Register will spin.

However, ultimately the meter should behave just like your current one does and they do indeed track Exports separately from Imports.

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@Blastoise186 thanks for your reply. I'm currently with EDF and awaiting details from their "technical department" , which I've requested via their customer service, about which make and model(s) of 3 phase smart meter they use. You're suggesting that the meters might be recording six separate energy movements ... it's what they do with the figures that I really want to know. Is there, for example, any legislation that says that they must only bill for the difference?

 We got our solar in late 2011, so benefit from great FIT rates and are not interested in SEG payments for our export ... we just want to minimise import. 

Userlevel 7
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For that, I think I’ll have to call in a favour from someone who knows more than me. This might take a few days and I need to get permission from a forum moderator first. If you’re Ok with that, I might be able to get advice from someone who knows a really good answer.

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@Abby_OVO a search on YouTube for "salokin solar powerwall" should find the video reports.

They are NOT "entertaining" in any way, but "dry" graphs and figures (originally intended mainly to be just my own record). There are a couple of years of monthly reports and annual summaries.

I could only start the reports after getting the Powerwall as, during the first nine years and a bit, I could only read solar production from the inverter and had no way of knowing how much I was "giving away" to the grid.

As we know, all households are different, so the experiences of others will not always be a good guide. We have "done well" by getting in just a couple of months before the FIT payments started to disappear.

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@Blastoise186 that was quick! It's not easy to find out what's happening with three phase domestic supplies and "nett" metering.

Our current non-smart meter will record the nett import only if positive. If we are consuming 2.8 kW on phase 2, 0.6kW on phase 1, zero on phase 3, and our solar is producing 3kW on phase 1, our meter will be ticking up at the rate of 0.4kW and so record 0.4kWh in an hour (if the Powerwall is not contributing!).

If we are just consuming 0.6kW on phase 1, 0.8kW on phase 2 and the solar is producing 3kW on phase 1 (and our Powerwall is full and the EV is not plugged in) then the meter will not be moving as there is nett export, and we will be exporting 1.6kW to the grid. This export is not currently being measured.

If a smart meter is going to record import and export of energy on the three phases, then summing the six figures later will not give the same answer when more is being exported than imported.

Are the smart meters able to continuously monitor the nett sum in the same way as the current non-smart meter? If not, our billing will change, and how it will change is what I wish to find out but cannot find. I don't need our export to be measured as it is irrelevant for our situation with FIT payments. I DO need to be billed only for nett grid import!

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@Blastoise186 I should have said, " I'm happy with that, and would be happy to get information wherever it comes from!"

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Hi @salokin , I might be able to add a little. With the 3 phase meter any summing would not include negatives as that would include exports and in effect be similar to a single phase being driven backwards but it would only aggregate any energy drawn from the grid. So similar to a single phase smart meter in registering and billing but actually able to record import and export on all phases. 
I was recently involved in a project with an existing 3 phase smart meter and the same question arose. What we chose to do was use an inverter which spread the export across phases to keep each phase as low as possible - this is still ongoing so I don’t have results as such so far. 

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@BPLightlog thanks, but definitely NOT what I wanted to hear if I've understood you correctly! In the summer we have lots of periods of consumption on phase 2 (swimming pool pump etc) with simultaneous excess solar export on phase 1, resulting in "free" running of the pool. If we were to be billed for all that phase2 import then life will become much more expensive! 

Userlevel 7
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@BPLightlog thanks, but definitely NOT what I wanted to hear if I've understood you correctly! In the summer we have lots of periods of consumption on phase 2 (swimming pool pump etc) with simultaneous excess solar export on phase 1, resulting in "free" running of the pool. If we were to be billed for all that phase2 import then life will become much more expensive! 

It does depend on the meter to some extent @salokin but that’s what I’ve understood so far. That’s also why the inverter being installed (in my install) has a system to feed back to the phases used.