I have two of these controllers. I've been using this for over five years. No questions! These work great and do their job. Those with negative reviews have DEFINITELY not read the instructions or are simply unfamiliar with solar controllers and proper solar connections. YOU MUST CONNECT THE BATTERY before connecting the solar panels to it. Otherwise you will damage the solar panels and the controller. This applies to all solar controllers. cheap or expensive. This controller works great if you follow the connection instructions. HAVE FUN!