Dual Voltage: Automatically detects whether you are using a 12V or 24V battery system.USB Ports: Most modern 10A models (like the popular blue "LandStar" style) come with two 5V USB ports, allowing you to charge your phone directly from the controller without an inverter.Protection: Prevents your battery from overcharging during the day and "leaking" power back to the panels at night.LCD Screen: Displays battery voltage and charging status so you know exactly how much "juice" you have left.