The product is used to control solar panel and battery in solar system automatically. It is easy to set up and operate.   Features: Automatically control the solar panel and battery in solar system.  Over-load & short-circuit protection.  Reverse discharging & reverse-polarity protection.  Under-voltage and over-charging protection.  Protection from lightning strike.  Prolong the battery life cycle and keep the load work well.  Easy to set up and operate.  Suitable for small solar energy system.   Specifications: Color: Black;  Rated Voltage: 12V / 24V (Auto Switch);  Rated Charge Current: 10A / 20A (Optional);  Rated Load Current: 10A / 20A;  Stop Power Supply Voltage: 10.8V / 21.6V;  Resume Power Supply Voltage: 12.6V / 25.2V;  Stop Charging Voltage: 14.4V / 28.8V;  Temperature Compensation: -3mV/Cell/°C;  Operation Temperature: -20°C~60°C;  Item Size: 103 * 95 * 38mm / 4 * 3.74 * 1.5in;  Item Weight: 117g / 4.14oz;  Package Size: 11.5 * 10 * 5.2cm / 4.5 * 3.94 * 2in;  Package Weight: 153g / 5.41oz;   Note: 1. Order of Connection: connect storage battery firstly, then connect the solar panel; Order of Disconnection: disconnect the solar panel firstly, then the storage battery; otherwise it will cause damage to the controller.  2. The inverter can't be connected to the controller directly.  3. The controller will generate heat during operation, please notice that put the controller on flat surface with good ventilation.   Configuration Selection: For 12V System, battery voltage is 12V, recommended input voltage of solar panel: 16-22V, when actual input voltage>50V, controller will be damaged;  For 24V System, battery voltage is 24V, recommended input voltage of solar panel: 32-44V, when actual input voltage>50V, controller will be damaged.   Package List: 1 * Solar Charge Controller;  1 * User Manual (English)