Power is generated from several power generation facilities and is then spread throughout the colony by cables. Excess power can be stored in Power Accumulators or Atomic Accumulators (once researched) for emergency situations.
Background[]
Electrical power on Mars comes mostly from renewable and cheap sources such as wind power (Wind Turbine) and sunlight (Solar Panel), but also from fission (Stirling Generator) and fusion based sources (Fusion Reactor) as the technology available advances. It is then distributed via an extensive and durable cable network.
Power Switches can be used to dynamically manage the flow of power in case of damaged cables or low power situations.
Storage[]
Power can be stored in power accumulators or atomic accumulators. This can be a strategy to use with solar panels in earlier game or on asteroids in the Below and Beyond DLC