6.3 Utility and Generation Metering

Quick Answer: LO 3.1.3 names a utility meter and a generation meter, and says the generation meter may be incorporated within an inverter. The utility meter is the supplier import/export meter — the Smart Export Guarantee (SEG) pays on exported units there. The generation meter (or inverter generation display) records PV AC output. MCS MIS 3002 Issue 6.0 clause 5.7.1 still requires a means of recording and displaying total AC generation. If that recording is used for billing or payment, 5.7.2 requires a Measuring Instruments Directive (MID)-approved meter with the serial number on the front. 5.7.3 says it should be readable without a tool, ladder or torch. 5.7.4 says battery round-trip from the grid must not corrupt billing or payment meters. Do not claim a Feed-in Tariff-era legal duty that every new SEG job must have a separate MID generation meter for SEG itself. This OpenExamPrep section is independent study material for 2922-34.

Why two meters appear on a 30-question paper

Candidates mix up what the supplier bills with what the inverter counted. LO 3.1.3 is that split. The knowledge test can ask utility versus generation without asking you to recite MID clause numbers. MCS contractors still live under MIS 3002 5.7, so a 2922 electrician who will work on MCS jobs must know both the handbook names and the installer-scheme metering rules.

Utility meter

The utility meter is the supplier meter at the cut-out / meter position. On a modern smart meter it usually has import and export registers. SEG, which took effect on 1 January 2020 after the Feed-in Tariff (FIT) closed to new applications on 31 March 2019, pays eligible generators for electricity actually exported to the grid. Obligated suppliers (those with 150,000 or more domestic customers) must offer a SEG tariff at a positive rate they set. Settlement uses the export register of that supplier meter, not a deemed percentage of a generation counter.

SEG eligibility for solar typically needs an MCS-certified installation and an export-capable meter. That is still not the same statement as “SEG is paid from the inverter’s kWh display.” The supplier reads export at the boundary.

Generation meter

The generation meter records the AC output of the PV system — the energy the inverter has converted from the array (as wired), not the leftover that happened to spill onto the street. Handbook v1.3 is explicit: that meter may be incorporated within an inverter. A dedicated kWh meter on the inverter’s AC output is the other common picture.

FIT-era habit was to fit a MID generation meter because the generation tariff was paid on generated units (with export often deemed or separately metered). New 2922 jobs are SEG-world. SEG pays exported units via the supplier meter. MCS still wants a generation display so the customer can see total AC generation. Those two sentences must both survive in your notes.

Do not write that every SEG installation has a legal duty, inherited from FIT, to present a separate MID generation meter to the supplier for SEG payment. Do write that MCS 5.7.1 still wants generation recorded and displayed, and that 5.7.2 upgrades that means to a MID meter when the figure is used for billing or payment of generated energy (remaining FIT sites, some landlord or private-wire bills, some contracts that pay on generation rather than export).

MCS MIS 3002 Issue 6.0 clause 5.7 — metering, not a 2922 unit pass rule

5.7.1 — A means of recording and displaying the total AC generation of the system shall be installed. An inverter display or portal that actually records and shows total AC generation can satisfy this. A dedicated meter can too.

5.7.2 — If required for billing and/or payment, that means shall be a meter approved under the MID, showing the serial number on the front panel where it could be photographed alongside make, model and reading. Installing a MID meter also satisfies 5.7.1. The serial-on-the-front rule exists so an audit photo is possible without opening a sealed terminal cover.

5.7.3 — The means of recording AC generation, dedicated meter or otherwise, should be accessible and readable by the customer without a tool, ladder or torch. An inverter whose only generation figure lives behind a bolted cover, in a loft that needs a ladder, or in a cupboard that is dark without a torch, fails the spirit of 5.7.3 even if 5.7.1 is notionally “on the PCB.”

5.7.4 — Where energy is taken from the grid, stored in an electrical energy storage system (EESS), and later returned to the grid or the installation, that energy shall not affect the veracity of any meters recording generated, imported or exported energy where those meters are used for billing or payment. The MCS note still uses FIT generation as the example of a payment meter you must not inflate. The same honesty duty hits import and export billing meters. The clause does allow the supply meter to record grid energy taken into the battery correctly as import. What it forbids is letting that same energy reappear as PV generation on a payment meter, or otherwise falsify a billing register.

MCS 5.7 is installer-scheme practice for MCS contractors. Completing 2922-34 does not by itself make the firm MCS-certified. The knowledge test still expects you to separate utility from generation and not to corrupt generation figures with battery round-trip.

Meter versus what it records versus who reads it

Scenario: overnight grid charge, daytime discharge, a naive generation counter

A hybrid is set to charge 10 kWh from the grid on a cheap overnight rate. The next afternoon the battery discharges through the hybrid’s AC terminals while the array is also producing. A naive “total AC output” or “yield” counter on the hybrid adds everything that left the AC terminals, including energy that entered from the grid at 02:00.

If that number is treated as solar generation for a remaining FIT claim, a landlord’s “solar supplied” bill, or any other payment on generated energy, MIS 3002 5.7.4 is broken: grid energy has been laundered as generation. A MID serial on the front does not make a wrong current transformer position honest. The meter must see PV AC generation, not hybrid throughput that includes grid-charged discharge.

SEG settlement at the utility export register is a different register, but it is not a free pass. Discharging stored grid energy onto the street can still show up as export. Supplier SEG terms and 5.7.4 both care when billing meters are involved. The supply meter should record the overnight charge as import — MCS says that correct import recording is allowed. The lie is on the generation (or other payment) register that pretends those kilowatt-hours were PV.

DC-coupled storage adds a second teaching point for handover, not a contradiction of 5.7.1: PV energy can charge the battery without becoming AC, so total AC generation can be lower than DC harvest. 5.7.1 asks for AC generation of the system. Explain that to the customer against the MCS annual AC estimate. Do not “fix” it by counting battery discharge of grid energy as solar.

Practical 2922 checks at commissioning: which display is the 5.7.1 generation figure; whether a MID meter is required because someone will pay on generation; whether that MID meter’s serial is on the front and the customer can read it without a tool, ladder or torch; whether the hybrid’s grid-charge path can increment that generation figure; and that the utility meter is the one SEG will use for export. Those five checks are the whole of LO 3.1.3 plus the MCS clause the industry will actually audit.