Photovoltaic tracking system on roofs

A photovoltaic tracking system disposed on a roof of a building, comprising:

• a photovoltaic panel group;
• a tilting system comprising a rod, a wheel, and a rail, wherein the rod has a first end connected to the wheel and a second end connected to the photovoltaic panel group;
• the wheel is disposed on the rail and configured to move linearly along the rail, and the tilting system is configured to tilt the photovoltaic panel group by a push or pull force from the rod when the wheel travels on the rail, wherein a triangle is formed by the the titling system, the photovoltaic panel group, and a portion of the roof, wherein a shape of the triangle changes when the tilting system tilts the photovoltaic panel group,
• a gear rack supported by mounting elements, including, but not limited to a supporting bump, connected to the said wheel by through coupling components including, but not limited to a connecting piece, wherein the gear rack is independent of the said rail, permitting an aligned movement into and out of the rail, which may facilitate a full range of motion for the said photovoltaic panel group;
• a stepper motor connected to and configured to move the gear rack to push the wheel.