... prorections of short circuit, overload,overcharging, overdischargingSpecification of 20W solar power system: Part NameItemTechnical DataSolar Power ParametersMax Output18V 20W Max Current1.1A ... 70%)CoverSize385 x 290 x 100 mm MaterialFireproof ABSFunctionCharger for household power generation system , fans, TV, computer, etc. 2012 New Design Solar Power System for Home Use