So the proper solution is to not lock your electrical panel, but to have a battery backup for your alarm system?
Many years ago (1978?) my first wife was an antique collector. So, I installed an alarm system. It was all hardwired with a battery backup.
I was told then... that the pros would just disable the phones. My brother who worked for the phone company confirmed that. He said the phone company would get trouble calls claiming that burglars had "cut the phone lines". But the lines weren't cut. The thieves would just pull the fuses (from the little plastic box on the home) and throw them in the yard.
I think serious alarms (besides the battery backup) now have cellular/mobile phones. I read [or saw on the news] of a local home that was broke into by cutting a hole in the wall using a chain saw. No alarm was triggered. If you have things that attracts the attention of a professional [scum-bucket] burglar...
they will take it. That is what insurance, and safety deposit boxes are for.
If your really more concerned about the local troubled kid down the street. Some sensors and cameras may help as a deterrent. And a UPS on your setup could keep it running.