convenient maintenance; that the do not need to conventional energy sources, does not pollution of the environment; can Acco 1. solar panel:20W~60W poly-crystalline silicon,20 years life.2. maintenance-free lead-acid battery,12V/24V 25AH~70AH, over charge and over discharge protection,3 years life.3. controller: soalr energy intelligent specialized controller, switch on/off by light and time.4. ...