Voltage plug setup: easily done just take special care in the phase-rotation
please note: this provides measurement and power to the EPM (Export Power Manager)
Current transformer (CT) clamps setup:
- note down the current ratio
- put the CTs on the mains grid connection (generally the thickest cables in the installation)
- ensure the phase rotation is the same as the voltage connections made (look at Appendix 1 for some hints for this)
Setup the MODBUS connections between inverters and EPM (see below the most complicated MODBUS network also look at Appendix 2 for troubleshooting of MODBUS networks). Also make the addresses (MENU > SETTINGS > SET ADDRESS) on each inverter sequential. Also enabled external failsafe on each inverter.
EPM settings - love the menu structure for the Solis Export Power Manager (explains a lot of the operation)
1.Inverter Qty. Set – number of inverters
2.Backflow power – export power limit
3.Set Meter CT – current transformer primary to secondary ratio
4.FailSafe ON/OFF – function to stop generating if the communications or CT stop operation
5.Backflow Work Mode - :
1.Average power over three-phases
6.PELD ON/OFF – Power Export Limit Device enable
7.System Update – menu to update the firmware
8.Reset Password – change the user password
10.Set EPM Regulator – set the capacity of the system (kVA rating of the combined inverters connected to EPM)
Appendix 1 - Troubleshooting CTs:
The first then is getting phase rotation correct if you struggling with that the best method to work out which is the correct CT for that phase:
- is put all three CTs on one of the phase wires;
- then go to Information screen (on the EPM) and check which phase current is the highest;
- then leave that CT on that phase wire and move the other two;
- and do the same on the next phase
The orientation (or polarity of the CTs is also extremely important)
•P1 on the grid side
•P2 on the load side
Mistakes can be made on the physical orientation as well as wiring into EPM
Sign of the active power shows when the system is importing or export
•Positive means export (load < solar production)
•Negative means import (load > solar production)
The best method to use here is to get the system into a known state (if you can turn off the loads, turn them off and get the PV inverters generating) you will know that the system is exporting and therefore the power on the display should be positive.
Conversely if you cannot turn off the loads, turn off all generation devices and then check the Active power on the LCD of the EPM and make sure it shows as negative.
If either of these are false reverse the polarity of the CTs.
Appendix 2 - Troubleshooting MODBUS:
Make sure you have the Qty of inverters set correctly.
Go to Inverter Power menu (MENU > ADVANCED INFORMATION > INVERTER POWER) and check which Inverters are showing power. If an inverter is communicating it will show at least 20W on this screen. However if it is not communicating it will show 0W. This will help you workout which inverter is connected and which is not.
Appendix 3 - Witness tests
There are three failsafe events for this product:
- CT failure - the inverters must go to low power. Do not remove the CTs under load - unless you know the system is lightly loaded do not let anyone perform this test
- COMs failure - if any of the COMs cables on the system break or an inverter stop receiving COMs from the EPM that inverter must stop generating at least.
- EPM lose of power - if the EPM is faulty or loses power the inverters connected must go to low generation
Do not let anyone test (1) they should understand since the secondary on the CTs will go to open circuit (high voltage)
For (2) you can just remove the cable on the bottom of the EPM or an inverter and see the power on the inverters go down
For (3) just remove power to the EPM and watch the inverters again go to low power
Appendix 4 - Commissioning
Even if a witness test is not required it is often suggested (and fun) to play with the system a little, wrap your head around the operation also to confirm it is working as expected.
To play with it you will need the PV inverters actually generating some power so you get to see a difference!
Check what the current Active power is on the EPM display.
Set the backflow power (MENU > ADVANCED SETTINGS > BACKFLOW POWER) to a negative value which is significantly higher than the current Active Power and watch the inverters go to lower generation (the EPM control the inverters DOWN). Then it back to a normal value and watch the inverters generate more power.
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