Multiplus II install not functioning correctly

DIY
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1

Hi,

I have just had a grid tied ESS installed, but both the installer (MCS accredited) & myself are struggling to make it function as we would expect.

The problem is that the MultiPlus-II does not appear to be seeing the condition of the grid and is constantly charging the batteries no matter what we do.

So far I have not seen the system supplement the grid from the batteries (I.e. discharge them) when I would expect it to do so.

As I have two ET112’s installed I would like to use the grid connected ET112 to control the inverter if possible.

System details:-

MultiPlus-II 48/8000

CerboGX Mk2 (Venus OS v3.6.4)

2x ET112 Energy Meters (One for grid & one for existing (Non Victron PV)

1x Current Transformer 100A/50mA

3x PylonTech US5000 batteries.

What I ‘think’ is working / correct:-

The inverter switch is set to position 1

The CerboGX is communicating with the MultiPlus, the PylonTech Batteries & the ET112’s.

The two ET112’s are showing sensible power indications for the grid & PV and are configured as such with the CerboGX.

The ‘Pages’ on the CerboGX look sensible apart from the AC Loads (Green)

The batteries are charging.

The system is wired as per

I have tried many combinations with the CT clamp (the instructions for this are unclear and the connections are not marked, but none have worked.

I have used VE.Config to examine the options (as best as I can understand), but I still can’t get the inverter to function correctly.

If it helps with answers I’m an electronics design engineer with 40 years experience, but new to ESS.

Help to fix this issue will be very welcome, as I’m lost now.

Regards

2

Did you setup the multiplus like step 7 in the manual?

3

Hi mac,

Thanks for the quick reply.

I have used the VE.Config, but section 7 does not give me enough detail to perform the configuration.

I have followed the link to the below and stalled on where to fit the temperature sensor. Does this go into the CerboGX, as I can’t see any where that it would on the MultiPlus.

Am I correct that I need to install the ESS Assistant as per the link below?

Sorry if these are a bit goofy replies, but I find the instructions a bit fragmented and not that specific.

4

VE configure can be used to program the multiplus and install assistants on the multiplus. For a grid tied ESS (and DESS) system you need to install the ESS assistant.

You can do this in the “assistants” tab in VE configure. Just select the “ESS assistant” and start it. Remember to set the correct grid code first.

The temperature sensor is optional, it can be connected to the multiplus to measure battery temperature, in your case the pylontech BMS takes care of that.

For measuring the grid you can use either the current clamp or the ET112 meter, only one is necessary. When using the current clamp make sure it’s plugged in all the way, sometimes this causes problems.

5

Could it be as simple as on switch in the wrong position?

5.1. On/Off/Charger only Switch

The switch is located on the underside to the bottom right of the product.

The switch has three positions. The centre position 0 is Off. The I position is On, and the II position is Charger Only.

When switched to ‘I / On’ (rocked towards the front of the unit), the product will come into operation and the inverter is fully functional.

If an AC voltage is connected to the ‘AC in’ terminal, it will be switched through to the ‘AC out’ terminal, if within specifications. The inverter will switch off, and the charger commences charging. ‘Bulk’, ‘Absorption’ or ‘Float’ will display, depending on the charger mode.

If the voltage at the ‘AC-in’ terminal is rejected, the inverter will switch on.

When the switch is switched to ‘II / Charger Only’, only the battery charger of the Multi will operate (if mains voltage is present). In this mode input voltage also is switched through to the ‘AC out’ terminal.

NOTE: When only the charger function is required, ensure that the switch is switched to ‘II / Charger Only’. This prevents the inverter from being switched on if the mains voltage is lost, thus preventing your batteries from running flat.

6

@SolarSponge Consider removing the CT (have you changed the setting on the inverter) when it was installed?), ensure the roles of the ET112’s are correctly defined and the grid one is upstream of all the loads, the ESS grid metering is set to external and you have selected the correct grid code on the inverte and the mode is optimised with or without battery life.

7

In addition to the comments can you show us the wiring diagram of the whole system from main DNO Head please.

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