that morningstar system is nice, going to cost a lot more than a DIY aurdino system
what ever is involved will have to go between the batteries and the parasitic loads
unless you want really heavy duty relay contacts, this means placing it between the DC fuse center and the parasitic loads
really if the batteries cannot carry the parasitic loads for a few days and the solar cannot recover, you have bad batteries and two little solar
yes i understand how bad the weather has been in Texas and this is not your normal situation
why not just disconnect the loads and leave the solar floating the batteries, obviously your talking detectors and alarms, not the fridge and appliances,
disconnected manually automatically or by dead battery..they will not be working
alarms are for when you are there, they nothing but make useless noise when there is nobody there to take action
