I have a SmartSolar MPPT 150/85 VE.Can connected to 6 320W Renogy solar panels wired in 2 parallel series of 3 panels on an RV. I have 15A fuses on each string and a 25A circuit breaker in between the fuses and the MPPT charger. The new system has worked fine for weeks, until one morning after a day of the charger being in float mode for most of the day, both 15A fuses were blown, but the 25A breaker was not tripped. I also noticed that the charger said that the PV Array voltage was within a volt of the battery bank when the array was actually at 0V and/or completely disconnected.
After replacing the fuses, the charger seemed to work for the rest of the day. By the next day, one of the 15A fuses was blown. Part way through the following day, the charger stopped charging altogether even though no fuses were blown or circuit breakers tripped.
Now, when the charger is in bulk mode during the day, it reports the battery voltage and PV array voltage but no (<5W) of actual charging, At night, it still reports a PV array voltage of approximately the battery bank voltage.