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Energy Meter Manual

4. FAQ

In this section:

Q1: Can I combine three ET112s for a 3-phase system?

No. Use a real 3-phase meter.

Q2: Can I use other meters, for example from other brands?


Q3: I already have a Fronius SmartGrid meter, can I use that?


Q4: What are the differences between the various 3-phase meters?

  • EM540 - REL200100100 - Carlo Gavazzi EM540DINAV23XS1X

  • ET112 - REL300100000 - Carlo Gavazzi ET112-DIN.AV01.X.S1.X

  • ET340 - REL300300000 - Carlo Gavazzi ET340-DIN.AV23.X.S1.X


  • The ET meters have no display. The only thing they have is an LED, which blinks in case of active communication.

  • The ET meters have two RJ45 sockets, but they are not used with the Victron RS485 to USB interface. Note the possible confusion because of yet another RJ45 socket in the Victron world though. Don't mix that with VE.Bus, VE.Can or Besides the RJ45 sockets, the meters still also have screw terminals access below the sockets for the RS485 wiring, which is how we advise to connect a meter to the RS485 to USB interface and then a GX device.

  • Since there is no display, the modbus address can no longer be changed on the meter. Combining multiple of those meters on one RS485 network is therefore not supported by Victron. You are advised to use multiple RS485 to USB interfaces.

3-phase meter only:

  • Measuring energy from single-phase PV Inverter on the second phase of a 3-phase meter actually works.

Q5: Will you keep shipping both 3-phase meters? (ET340 & EM540)

Yes. There are still situations suitable for each. See Q8.

Q6: Can I buy those meters directly from Carlo Gavazzi instead of from you?

Yes. That is also why we make no secret of the CG part numbers.

Q7: I want to use Current Transformers (CTs), is that possible?

Yes. You can buy a CG EM24DINAV53DISX or a CG EM530DINAV53XS1X directly from Carlo Gavazzi or one of their distributors. Even though Victron does not stock that type of meter, we do support it in our software.

Q8: What’s the difference between ET340 and EM540 in 3-phase systems?

These meters have a different way of calculating the total of energy imported and exported.

In the ET340, the energy imported and exported is counted at each individual phase and then the Total is provided from the sum of those values.

In the EM540, the energy imported and exported is counted as a total power, with net differential readings from each phase cancelling each other out.

Which Energy Meter is most suitable depends on the measuring configuration in your country. It is most common in Austria and Germany for example to only be billed for the total in a 3-phase system. So it is more accurate to use an EM540 to match the billing.

So if you are exporting from one phase and importing from another phase after the energy meter, but before the billing meter, then you will not be charged for this, and the meter should not count it as an import and an export.

This is also how Victron’s phase compensation feature works, to make the most of the cost savings for an ESS system when there is a differential in generation and load across different phases.

Q9: Can I use an isolated USB-RS485 interface?

Yes. The interfaces we sell are non isolated; suitable for most use cases.

In case an isolated one is needed; purchase it directly from Hjelmslund Electronics.

  • USB485-STIXL : Isolated USB to RS485 converter

Q10: Can I use Victron Energy Meters instead of a Victron Inverter/Charger to make use of a GX device (e.g. Cerbo GX), VRM and other features?

Energy Meters are intended to supplement a Victron Inverter/Charger in the system. Energy Meters are currently limited in their potential applications. Each Energy Meter is only intended to provide a specific piece of additional information - total loads on AC input and grid import/export, or AC PV inverter and AC generator production without network communications.

However, it is perfectly possible to initially use just a GX device together with an Energy Meter to determine and record the consumption, for example of houses/buildings, heating systems with heat pumps, ventilating and air conditioning or production facilities. Afterwards, the collected data can be evaluated and a decision can be made about the dimensioning of the required Victron inverter/charger(s), the solar system and the type, size and number of batteries.

With GX device firmware version 2.80 and later, they can also be used for other purposes e.g. to measure specific, arbitrary AC loads or circuits for example. But this should not be considered a replacement to having a Victron Inverter/Charger. Attempting to use other brand battery inverters and trying to substitute their lack of data connectivity to the GX device by using Energy Meters will not work as expected.