The City of Lancaster, California’s solar energy system implementation regulation requires all new single-family homes to have a solar energy system in order to receive a building permit. The mandate includes subdivisions, requiring the subdivider to meet the aggregate energy generation requirement within the subdivision (as calculated by the per-unit energy generation requirement multiplied by the number of homes in the subdivision). Alternatively, a homebuilder may choose to meet the solar energy generation requirement by purchasing solar energy credits from another solar-generating development located within Lancaster.