A system includes a photovoltaic module having photovoltaic cells, each having a width, and a roofing shingle having an exposure zone and a headlap zone. A plurality of slots extends from the exposure zone to the headlap zone and define tooth portions. A first one of the tooth portions has a first side defined by a first slot and a second side defined by a second slot adjacent to the first slot. The first tooth portion has a first width that is the photovoltaic cell width multiplied by a first positive integer. A second tooth portion has a first side defined by a third slot and a second side defined by a fourth slot adjacent to the third slot. The second tooth portion has a second width that is the photovoltaic cell width multiplied by a second positive integer different than the first positive integer.