Solar panel on top of the lamp recharges the battery. Outdoor lamps are used for lawn and garden decorations. Indoor solar lamps are also used for general illumination (i. e. for garages and the solar panel is deattached of the LED lamp). Solar lights are used for decoration, and come in a wide variety of designs. They are sometimes holiday-themed and may come in animal shapes. They are frequently used to mark footpaths or the areas around swimming pools. Solar lamps recharge during the day. At dusk, they turn on (usually automatically, although some of them include a switch for on, off and automatic) and remain illuminated overnight, depending on how much sunlight they receive during the day. Discharging time is generally 8 to 10 hours. Some solar lights do not provide as much light as a line-powered lighting system, but they are easily installed and maintained, and provide a cheaper alternative to wired lamps. Source: Wikipedia
Source:
http://en.wikipedia.org/wiki/Solar_lamp