Sunny Home Manager 3-phase with external CTs

[jonc_uk]

Hi All,

I have decided to switch to an SMA based system. The first step is to install a Sunny Home Manager 2.0 which will monitor the grid import/export and deal with the export limitation of some new Sunny Boy inverters.

I installed the Home Manager last week but have been having trouble with the external CTs. These are required since the import can be greater than 63A per phase. It is set up in the Sunny Portal and all lights are green.

I followed the instructions for configuring the external CTs in the Device Configuration on the Sunny Portal where you set to 'Complex Configuration' view, set the 'External current transformer' parameter to 'Yes' and then you set the 'primary current' and 'secondary current'.

Here is the first problem - primary current and secondary current, but with no units specified? I installed some spare Enphase 100A CTs which have a turns ratio of 2500:1 - so 2500 and 1? I have tried this and also (making an assumption of A for primary and mA for secondary) 100 and 40.

At this stage, I got zero readings.

I managed to get some readings displayed after I gave up waiting for SMA support and installed an Energy Meter on one set of PV - magically, grid readings appeared for the past four days.. although they didn't look correct.

I now have the CTs on the Energy Meter phase wires so the system should be reporting exactly the same on the grid import/export as on the PV generation. However, I am still getting nothing reported.

I am new to SMA kit and so don't know what quirks the system has - should I be power cycling the Home Manager if I make CT changes for example? Also, is there any debug info if I connect to the Home Manager directly? I know it has a web server since it can serve up the software license page.

How responsive is SMA support usually? Other than batting my ticket back with instructions to ensure the firmware is up to date (they didn't bother to check their systems to see it was) they have been silent.

Any help or suggestions appreciated. I still have 5x Sunny Boy and 3x Sunny Islands to install but don't want to move on to these until I have this sorted.

(and sorry for the long post!)

[Tinbum]

From the manual;

Current transformer requirements:
The installation version of the current transformer (DIN rail or folding over, with or without connecting cable) can be
freely selected, depending on the on-site conditions. Observe the following requirements during the selection:
☐ Use a current transformer for 5 A secondary current with accuracy class 1 at least.
☐ Select a current transformer type according to the grid connection. Example: type 100/5A for up to 100 A grid
connection.

[jonc_uk]

Aagghh. RTFM.

Thanks Timbum.

Much higher secondary current than the CTs I have. 20:1 instead of 2500:1

Need to rethink some stuff as I can't run 5A down 50m of twisted pair. (Not that I was anyway with 3-phase potential on the wires ).

[Tinbum]

Aagghh. RTFM.

Thanks Timbum.

Much higher secondary current than the CTs I have. 20:1 instead of 2500:1

Need to rethink some stuff as I can't run 5A down 50m of twisted pair. (Not that I was anyway with 3-phase potential on the wires ).

Yes- think industrial standards not domestic. SMA stuff is really good reliable kit.

Edit Put the CTs and home manager in the same place and run the data down the twisted pair??