13VAC5-200-150: Thermal storage

Devices constructed for the primary purpose of storing thermal energy collected and converted by a solar heating system shall be considered solar energy equipment. In passive solar heating systems the thermal storage is often incorporated into the building envelope in the form of thick concrete slab floors or masonry walls insulated on the exterior of the structure. If the thermal storage is serving a dual function as floor or wall of the structure, fifty percent (50%) of the cost of the floor or wall shall be considered solar energy equipment and eligible for tax exemption.