If you only need to backup power 12/24/48V devices, then you can skip the mains voltage inverter and use a battery-backed power supply. MeanWell comes to mind —

If you only need to backup power 12/24/48V devices, then you can skip the mains voltage inverter and use a battery-backed power supply. MeanWell comes to mind — they make these power supplies for security and telecom systems.