There should have been a battery disconnect put in between the QCA13 rectifier and the batteries. This is the very reason for the disconnect is to isolate the batteries for maintenance. If there is not one you can probably still do it without issue, it will cause an alarm condition but that should go away after the string is reconnected. There may also be a sense lead tied to the string of batteries, make sure you hook that back up. I have worked DC hot a lot of times without issue, but if your uncomfortable at all then by all means power it down.