Which is correct - the Solar PV inverter thro' the Consumer Unit or Utilty Meter?

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  • MattyHi
    Junior Member
    • Feb 2022
    • 4

    Which is correct - the Solar PV inverter thro' the Consumer Unit or Utilty Meter?

    We recently in Dec 2021 had a large PV solar install completed on our house. A new 24 panel [385W each] Solar array at 8kW by a seemingly professional company. Disappointingly the install has issues, the main one being that the house utilty meter has the same consumption rate as before the solar install started! This suggests there is wiring config. or equipment fault issue somewhere or the meter cannot cope with Solar [we do have good solar yields].

    Either way we are none the closer to getting either the solar installer back to fix it quickly [I don’t think they understand it!] or the Utility company to check the meter! All this in rapidly rising energy prices ….. pause to weep …… seriously this is cry for help please, we have spent a fortune for nothing!

    One thing that stands out to me, being a lighting engineer [as a I have some electrical knowledge - although a little knowledge can be a dangerous thing!] is that the Solar Installer has wired the Solar Arrays Inverted 240V output not direct to our Consumer Board but has put it through our Utility Meter with the grid supply [on a single split combined cable]. When I asked the solar installers engineer how the Utility Meter can tell the difference between electricity we are consuming direct from the grid or through the Solar he just shrugged his shoulders and exclaimed that it just can!

    I attach an image of our electrical utilty meter [ a SMET 1 – Elster AS300P] cupboard with the solar installers wiring config displayed.
    The question to those in the know is should the Solar always be through the consumer unit first [as in schematic A] or through the utilty meter [as in schematic B] shown , or does it depend on other factors?

    Any help or direction most welcome. Thank you.
    Matt
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    Last edited by MattyHi; 03-23-2022, 01:41 PM.
  • bcroe
    Solar Fanatic
    • Jan 2012
    • 5199

    #2
    Your utility KWh meter has the utility (Power Co) connected on one side, and
    your house/consumer loads connected on the other. Your solar inverter output
    must be connected at the house/consumer side, to feed your loads directly
    (instead of thru the meter), and/or to feed back thru the meter (and be credited)
    to the Po Co. If the inverter is connected at the Po Co side of the meter,
    your generation is going out to help the PO Co serve consummers, without
    you getting any meter credit. Bruce Roe

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    • Mike 134
      Solar Fanatic
      • Jan 2022
      • 386

      #3
      Judging by the photo you are not in the USA?

      Comment

      • Ampster
        Solar Fanatic
        • Jun 2017
        • 3650

        #4
        Originally posted by Mike 134
        Judging by the photo you are not in the USA?
        Yes, so the operative question is how many people on this forum are familiar with that kind of system?
        Last edited by Ampster; 03-24-2022, 08:41 AM.
        9 kW solar, 42kWh LFP storage. EV owner since 2012

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        • MattyHi
          Junior Member
          • Feb 2022
          • 4

          #5
          Sorry just to clarify this post relates to the UK. However the principle of Solar set up concerning wiring config i.e. " utility meter - consumer unit [load] and Solar PV output would apply world wide but i accept the visual looks different. Perhaps if we stick with the principles of flow diagrams ...... thanks all the same . I appreeciate any guidance.

          Comment

          • Ampster
            Solar Fanatic
            • Jun 2017
            • 3650

            #6
            The traditional flow to the grid is from the solar panels through an inverter through a circuit breaker on a breaker panel through the utility meter. The loads are served by other breakers on that breaker panel. That would be A in your diagram. Bruce Roe describes what would happen if the connection were like B in the diagram.
            Last edited by Ampster; 03-24-2022, 08:44 AM.
            9 kW solar, 42kWh LFP storage. EV owner since 2012

            Comment

            • Mike 134
              Solar Fanatic
              • Jan 2022
              • 386

              #7
              Originally posted by Ampster
              The traditional flow to the grid is from the solar panels through an inverter through a circuit breaker on a breaker panel through the utility meter. The loads are served by other breakers on that breaker panel. That would be A in your diagram. Bruce Roe describes what would happen if the connection were like B in the diagram.
              X2!! your term "consumer unit" tossed me for a loop. BTW B works but only if the utility company comes and reads your generation meter and subtracts those KWHs from their meter reading.
              Since you said the Utility meter consumption hasn't decreased you're apparently wired up as in "B" and the utility has to read your generation meter to properly credit your power generation

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