A heat panel system for preventing ice formation about a roof or gutter includes at least two heat panels that are connected using a fastener. The heat panels each include a body including at least one channel configured to accept a heating element. Tongues and grooves or other mating arrangements on the panels and the fastener permit two panels to be joined by a fastener so as to inhibit relative lateral movement and enhance heat transfer between panels. A single panel or a multi-panel system can be mounted directly on the roof, and/or a single panel system can be mounted in a gutter. By using these heat panels and fasteners, heat panel systems of varying widths can be made using the same supplies.