These are power utilities that provide electricity to households or business establishments which are far from the main electrical grid. It is very useful for residential or commercial sites located in far-flung regions where connection to the national electricity grid may be too overpriced. It uses solar panels to charge large batteries from which power can be generated even during non-daylight hours and enables you to bring in utility power at your residences at an affordable cost. They are also known as Remote Area Power Supply (RAPS). A generator or a battery backup system is usually necessary when using SPS in case there may be grid power outage.