Columbia Law School’s Center for Climate Change Law developed the Model Small-Scale Solar Siting Ordinance, which includes several helpful solar energy system definitions. The model ordinance defines building-integrated photovoltaic (BIPV) systems as those that integrate photovoltaic modules into the building structure, such as the roof or fac¸ade, but which do not alter roof relief. The model defines freestanding or ground-mounted solar energy systems as those directly installed in the ground and not attached or affixed to an existing structure and defines rooftop or building mounted solar energy systems as those mounted on top of a structure or roof as a flush-mounted system or as modules fixed to frames that can be tilted toward the south at an optimal angle. Finally, the model ordinance defines small-scale solar as solar photovoltaic systems that produce up to ten kW per hour of energy or solar-thermal systems that serve the building to which they are attached and that do not provide energy for any other buildings.