MPP LVX 6048 Battery voltage back feeds to PV

[SoOrSolar]

I have a LVX 6048 offgrid with BYD 48v Fortress batteries connected. We were moving the array to a better location and they are disconnected. The old PV setup on the roof had 2 strings running into a combiner box. We moved the array 600ft up to the mountain top along with the combiner box. The array has not been re-installed yet. When disconnecting the old combiner, the owner was shocked by the wires coming from the PV connection on the MPP. It measures 52.1 VDC (Battery Voltage). My first question is WTF? He flipped off the breaker from the batteries and left overnight. When turning back on today, there is no voltage present on the PV circuit with the MPP on. Again, my question is why? There are also some A/C input (gen) irregularities with this unit but that is another discussion. Any thoughts?

 

[hiru22]

I've had a similar experience. After reinstalling the array in the new location, did the inverter keep working as usual?

 

[iamrich]

This happened to me as well and I have learned to not trust any of the connections. If the unit is connected to any power source (utility, PV, Battery) treat the whole unit as live. I always disconnect the wires from the LVX first.

 

[OffGridForGood]

This was discussed in a past thread, basically the AIO terminals can have voltage on them 'backwards' from what we expect. Treat everything as live.

 

[Dagoth Ur Does Solar]

I have a little 12v MPP PIP-1012 and I damn sure de-energize the entire system before I screw with stuff. PV disconnected, AC input disconnected, I even unplug my devices downstream from the inverter just because.

I don't trust these cheap Chinese units to not shock me.

 

[AntronX]

These AIO inverters do not have galvanic isolation between PV input and AC in/out and can have up to 450V on PV terminals in relation to ground.