Bidirectional Solar Tracking System

Solar power is the conversion of sunlight to electricity. Sunlight can be converted directly into electricity using photovoltaic (PV). In this project, photovoltaic is used as a solar converter and working together with a solar tracker. Solar tracker is used to boost up the energy gain of PV arrays. There are few considerations about solar trackers such as cost, reliability, energy consumption, maintenance and performance.

Electro-optical solar trackers are usually composed of at least one pair of anti-parallel connected photo-resistors or PV solar cells which are, by equal intensity of illumination of both elements, electrically balanced so that there is either no or negligible control signal on a driving motor. In auxiliary bifacial solar cell, the bifacial solar cell senses and drives the system to the desired position and in PC controlled date and time based, a PC calculates the sun positions with respect to date and time with algorithms and create signals for the system control. This thesis use the combination of three methods above method in order every minute there is 90 degree incident light fall on the PV cells.

As briefly, this thesis is about a bidirectional solar tracking photovoltaic system. Bidirectional movement is being actuated by two dc motor. A H-type motor driver is designed in order to control motor in 4 mode, forward, reverse, forward breaking and reverse breaking. Motor is being controlled by a programmed PIC18F4250 that receive signal from sensors.

The motors change the altitude and longitude angle of 20 pieces series connections of PV cells, in order the sun’s incident angle is always perpendicular to the PV cells. Most of the converted energy is used to charge up batteries instead of supplying power for the control and driving system. Dimension of the PV cell is 15cm X 30cm, total 20 pieces PV area is 0.9m.

Dimension of mirror is 15cm X30cm, total 30 piece mirror area is 1.35m. Solar concentration ratio is 2suns. V of solar cell is about 16V and 130mA, hence nearly 2W per piece. Estimated cascade 20pieces of PV will give 35W due to several power losses in the circuitry and other relevant factor.