off the grid

Short definition from Wiktionary

Adjective

1. 1
   Not using electricity from the public electrical supply system.
2. 2
   Not reachable via a publicly available communication system, such as the Internet or a mobile telephone network.
3. 3
   Isolated; in a remote location; in seclusion; not participating in some official process or system.
4. 4
   Alternative form of off the grid.

Adverb

1. 1
   In or into a situation or place in which electricity from the public electricity system is not used.
2. 2
   In or into a clandestine or isolated situation or place, especially one in which public communication is curtailed.
3. 3
   Secretly; in a clandestine manner.
4. 4
   Alternative form of off the grid.