Since Morningstar controllers are passively cooled without any internal fans or moving parts, they are very reliable. Fans and other parts are subject to failure and replacement can be very problematic, especially for controllers installed in difficult-to-access remote areas. But in addition to issues related to mechanical performance, and debris drawn into the controller by these fans, the noise they create can be irritating in residential applications. With passive cooling, you not only minimize the chance of defects, but you also benefit from the sound of silence.