I dunno, are you able to plug (110v) it in to charge the batteries...
It sounds like it trying to charge the batteries, but being in the barn can't and the batteries are critical Low...? Something might be draining them? or, as it says, not connected, but shouldn't be causing the alarm to go off. Panels stop charging when night comes and the alarms don't go off..
If that makes any sense...
Just rambling here, trying to remember what mine was.. but my controller was going knutts... reading 12.5 on moment and then not the next... it was a loose connection so maybe that's it..
Loose connection under the sink... the wire kept making contact, then wouldn't...
Take it in...