I´ve got the error, that MPPT is off and batterie not charging because input voltage is too low.
I´m running a SmartSolar MPPT 100/15 connected on 4 solar panels connected in series. If the panels are connected to the MPPT, I can measure a voltage about 14V. If the panels are not connected, voltage is about 60V which are normal operation voltage.
As I have a second identical string, I connected the panels to the other one and everything works well, so the panels are OK.
I connected the panels from the first MPPT to the second one with the failure message and the MPPT gave me the same message, it´s not charging because of the voltage has to be 5V higher than the batteries’ voltage.
MPPT software is up to date.
MPPT is just 2 years old, any idea what the problem could be?
The normal Cause of this is you have a poor connection somewhere between your panels and the MPPT, like a loose, corroded or oxidised MC4 connector causing a high resistance joint. Sometimes it is a failing panel with a failing joint inside, but usually the wiring.
When you disconnect the panels from the MPPT they are open circuit so even with a high resistance joint the voltage gets up to 60V. A voltmeter draws very little current. When you connect the MPPT, it tries to draw full current from the panels so you get a lot of voltage drop over the poor connection and the input voltage drops to just over the battery voltage.
An open circuit voltage test is not good enough to test if a set of panels is working due to the effect above, you need to do a short circuit current test as that would show a much lower current than the spec due to the high resistance. However, not many people have the kit for this if Isc is above 10A which most basic multimeters are capable of.
Hi, thank you very much for your help. Sorry if my troubleshooting was poorly explained. I doublechecked each connector and each elements without any negative result. I connected the complete string with solarpanels, cables and connectors from the MPPT which is not working to my other MPPT and everything works well as expected. So I can definitely rule out, that there is something wrong with the panels, connectors or cables. Voltage and power are OK. I did the same with the connection from the batterie to the MPPT. It always gave me the result, that with one MPPT everything works well and connecting the other one it gives me the error message as described.
Same applies then, there will be a poor connection / hogh resistance joint inside the MPPT between the input terminals and the power electronics then. Talk to your supplier if it is still under warranty for an RMA.
Hi, again thank you very much for your advice. The MPPT is damaged. After contacting the dealer, Victron has accepted RMA. So they will replace the MPPT with a new one. So I will mark the thread as solved.