Portable interior / exterior application Sunny, partial and moderate cloud conditions. Designed to be used for exterior applications by being mounted to exterior wall or set on an solar stand (stand included). External application requires 3” duct hose (not included), to be attached to 3” duct ports, penetrating exterior wall and run into room allowing warmed air into the space. Under good winter sun conditions, up to 25 degrees F (14 degrees C) may be added to the ambient temperature in the room with a maximum air flow from the solar fan of 40 CFM. Quiet solar powered waterproof recirculating fan distributes heated air and has adjustable speed control knob.