Definition:
A stand-alone power system, also known as remote area power supply (RAPS), is an off-the-grid electricity system for locations that are not fitted with an electricity distribution system. Typical SAPS include one or more methods of electricity generation, energy storage, and regulation. Electricity is typically generated by one or more of the following methods: Photovoltaic system using solar panels, Wind turbine or Diesel or bio fuel generator.
Further Reading:
Book: The Unified modeling Language user guide by Grady Booch, James Rumbaugh and Ivar Jacobson