question

Martyn Duerden avatar image
Martyn Duerden asked

Conversion to Ess

Hi all,


I have a multiplus-II 48 which is currently operating as a backup for when grid fails, it is in a house.


The mains is split at an ATS-Automatic transfer switch, the multiplus-II is installed at a remote shed.


When mains fails the ATS switches to the multiplus-II but with a 16A limit, in normal operation the house load does not go through the multiplus-II because it is limited to 16A and 40A is peak load. In backup mode (mains has failed) the power to the remote location is off the house is on.


I am looking at adding PV via the 250/60 MPPT in to the multiplus-II.


I plan to modify the ATS to provide unswitched power at all times to the remote location, Install venus/colour gx at the remote position and AC monitoring at the origin (60m apart)


Q1, Can I use cat5/6/7 for comms between the GX & AC sensor with the victron usb adaptor at the GX


Q2, Given in standard operation the loads do not go through the multiplus-II at all will it just backfeed PV & Battery capacity to the local grid up to 16A? (The AC 1 & 2 outputs are basically disconnected in standard operation hence forward feeding is not possible)


Q3, Can I get standard RS232 (not TTL) out of the GX?


Q4, How do I prevent back-feeding on mains fail? I fear the main contactor will stay energised as it will sense the voltage from the Multiplus-II which in turn will prevent switch over to backup.


Thanks


Martyn

@mvader (Victron Energy Staff)

Multiplus-IIMPPT ControllersESSgx devicers485
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
Paul B avatar image
Paul B answered ·

I am no expert but I have answered as best I can.

Q1, Can I use cat5/6/7 for comms between the GX & AC sensor with the victron usb adaptor at the GX

This should be ok  but distance etc could cause issues,  it will be  give it a go and see what happens

Q2, Given in standard operation the loads do not go through the multiplus-II at all will it just backfeed PV & Battery capacity to the local grid up to 16A? (The AC 1 & 2 outputs are basically disconnected in standard operation hence forward feeding is not possible)

yes as  depending on setting in the ess etc

Q3, Can I get standard RS232 (not TTL) out of the GX? 

no I suspect only Can and some binary


Q4, How do I prevent back-feeding on mains fail? I fear the main contractor will stay energised as it will sense the voltage from the Multiplus-II which in turn will prevent switch over to backup.

Well the multiplus II has inbuilt anti Island I believe, so this should disconnect.


2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.