The major application of the stand-alone power systems is in remote areas where utility lines are uneconomical to install due to terrain, the right-of-way difficulties or the environmental concerns. For remote villages farther than two miles from the nearest transmission line, a stand-alone wind system could be more economical. According to the World Bank, more than 2 billion people live in villages that are not yet connected to utility lines.
The analysis and design of stand-alone systems can be challenging, due to the large number of design options and the uncertainty in key parameters, such as load size and future fuel price. Renewable power sources add further complexity because their power output may be intermittent, seasonal, and nondispatchable, and the availability of renewable resources may be uncertain. Moreover, in most cases the stand-alone power systems must have some means of storing energy, which can be used later to supply the load during the periods of low or no power output..