No DC LED / No PV Voltage - Troubleshooting

Following installation of Solar Panels and the power flow screen of the Inverter shows No PV production plus the Green DC LED is not lit. Our first recommendation is to check and confirm the correct polarity of the MC4 Connector Plugs. The Positive Cable from the Solar Panel String should be terminated with the correct MC4 Plug which connects to either MPPT1 + or MPPT2 + input. The Negative Cable should therefore connect to the corresponding MPPT1 – or MPPT2 – input.
Please refer to the detailed information in the “PV Connection” section of the appropriate User Manual for the Inverter being installed.

To check and confirm correct polarity, connect the positive lead of a multimeter (set to read DC Volts and select range appropriate to the expected voltage of the String) to the positive of the MPPT input you wish to check. Then connect the negative lead to the corresponding negative of the same MPPT input.
Ensure the PV Isolator is in the OFF position. The observed DC Voltage must be positive and be greater than the minimum 125V start up voltage required for the MPPT input.

Fig1 shows the MPPT Terminals on the integral PV Isolator of a 3.6kW single phase Inverter. Fig2 shows the display of a multimeter measuring –222 volts DC indicating a reverse polarity condition and the MC4 Plugs must be removed and placed on the correct positive and negative cable. Please refer to the detailed information in the “PV Module Wiring” section of appropriate User Manual for the Inverter being installed.

Once the polarity has been checked and confirmed as being in the correct orientation and showing a positive voltage greater than 125V DC the Green DC LED should now be lit. You should also now be able to view the PV production information on the System Power Flow screen or Status screen of the Inverter per images below.

You can also view the PV Voltages in the Sunsynk Connect App. Navigate to the Plant and at bottom of screen, tap on ‘Equipment’ and then tap on the ‘Inverter Serial Number’. At the top of screen you will now see ‘Output’ selected as the default option. Tap the ‘Input’ tab and you will be able to see PV production data and PV Voltages from your Solar System.