An off-grid solar power system is one that gets most or all of its electricity from the sun using solar panels (photovoltaic panels) and none from a power utility such as a hydroelectric dam, nuclear, coal or natural gas fired plant, ... The grid, which the system is "off" of, refers to the complex network of power lines that connect the utilities to the numerous buildings that use the power. Since in many locations there may be clouds for days or weeks at a time, off-grid systems usually have a back-up generator as well. In addition they may have wind turbines, microhydro and other small electricity generating means.
The various parts are: