Originally Posted by SteveJ
Before plugging in our portable panels I either cover them or have them face down so there is no output. The controller is hardwired.
That makes it totally safe, but probably isn't necessary from what I have gotten from manuals for controllers. Many of them show a switch in the line to the panels which is really the same thing. There big concern is having the battery in the system whenever the panels are connected and seeing sunlight. Worst case, as mentioned earlier, would be to plug in or flip a panel switch on with no battery in the circuit and bright sun on the panels.
Since with portables it is easy to do, no reason not to, though, as it is foolproof and depending on the plug style you might see some arcing.