The height limitations of this chapter shall not apply to antennas which do not exceed a height of 200 feet and which are accessory to an otherwise permitted use, silos, barns and other agricultural structures, church spires, cupolas, domes, monuments, water towers, fire observation towers, electric transmission lines and supporting structures, windmills, smokestacks, derricks, conveyors, flag poles and masts, or aerials, solar energy facilities, chimneys and similar structures to be placed above the roof level and not intended for human occupancy, provided that:
(1)
These exceptions are shown to be necessary to accomplish their purpose.
(2)
These structures are shown to be compatible with uses in their immediate vicinity.
(3)
The aggregate roof area covered by these fixtures shall not exceed 20% of the total roof area.
(4)
The height of roof-installed water towers, ventilators, skylights, mechanical equipment, solar energy facilities and other similar structures shall not exceed a vertical height of more than 15 feet above the top of the roof.