I am installing a 150/85 SCC on a 940 watt system fifth wheel. When I shut down battery system, do I need to kill the PV side first to prevent harm to the SCC. I have been reading that shutting down the batteries without disconnecting the PV power that I could harm the SCC.
Hello. Yes, the best procedure for disconnection is to remove PV power first and then the battery bank. And the reverse order when installing. If I'm not wrong this is the adopted procedure for most MPPTs/regulators in general irrespective of brand.
To explain a little more from my experience, it may harm the SCC but also high chances of "confusing" the SCC in terms of what battery voltage to work with. For example, leaving high PV voltages connected to the SCC without battery connection, may confuse the SCC to change its battery voltage setting from 12V to a 36V, if it was set for 12V initially. When you reconnect the battery bank, you would probably get some MPPT alarms. Usually it can be sorted out by changing the battery voltage to the right battery bank voltage. Ofcourse this change has to be done immediately. We wouldn't want our battery bank to get the wrong high charging voltages for too long.
