You seem to have more power problems there than Zimbabwe does.....
I seem to remember seeing a device you could attach to a cellphone that would send SMSs if various conditions occurred - it had a number of lines to which you could attach clean contacts which triggered the SMSs. You could program the messages and the number they were sent to. It seems you have cell service there, maybe this would be a solultion? (use a normally closed contact on a relay connected to a wall wart.... put a 4 hour time delay in to avoid false alarms.....that would mean a battery, but that's easy.....)
This was yonks ago in the days of GSM phones, but I am sure something is available now that you can use. Maybe just an alarm system with the power alarm being a certain zone. it should not be more than the cost of a new freezer!
Maybe in the next decade or so, all these houses will be fully wired with sensors (and modest battery backup) so they can send you an alert that power is out, whethr due to a storm or utility company cut-off. Maybe it will be like HAL in 2001--the house will tell you it is "dying".