Directly from solar panel (in mid day blue sky conditions) I have around 20w output. when I connect to the MPPT (that is connected to my 360ah battery bank) the voltage drops always to a little bit under what is the current battery bank voltage.
Solar panel seems working well, Mppt seems to work well but when they are connected I have always a drop in voltage that is never sufficient to be above battery bank voltage.
I check all cables and I am using 4mm2 electrical specific wires.
All hardware is new.
Do not know what to say more. It makes me question if the battery bank needs to be quite low on voltage in order for the MPPT starts to charge.
That is a very small solar panel for that sized battery even if it was producing 60W, it may just be too small, especially if it only produces 20W. Do you have anything connected to the output of the load terminals.
When the panel voltage drops too far it usually means that there is a high resistance in the cables somewhere or a faulty cable connector or breaker or a faulty panel. Disconnect the solar cables from the controller and then measure the short circuit amps with a multimeter set to DC current and make sure that the required current is getting to the controller. Do the same on the panel on its own.
If it is a Smart Solar then use the Victron Connect app to look at the performance and post a screenshot of the performance, settings and history pages.
Thank you so much for the help. I am going to connect the solar just to my start battery. It’s smart so I see on the app. It seems a faulty cable. But I’ll check again.
I have other solar panels. I use this only for floating the batteries on dock or on the hard.
In order for the MPPT to work, and start charging, the panel voltage must reach 5V above the battery voltage (actual battery voltage at that time, not nominal voltage) With small solar panels, this can be problematic, as the Voc can be in the 15 - 17V region.
In this case, you are better off with a PWM charger, not an MPPT unit.
Best solution is to add another solar panel (identical) in series to increase both power and voltage.