Solar cells are one of the most widely used alternative sources of energy due to the growing demand for energy in the world and the declining supply of traditional energy sources. However, due to the movement of the earth around the sun and around its own axis, generated electrical power varies according to our position on earth and hour of the day. They are most efficiant when the sun is shining perpendicular to the solar cells, which cannot be achieved with permanently mounted photovoltaic modules, so we increase the generated power by using a solar tracker.
This bachelor's degree thesis describes the complete process of designing and making a small sun tracker system that can be used for demonstration of solar cell and photovoltaic module operation under different conditions. This system contains a dual-axis solar tracker with the option of automated tracking with the help of photodetectors or manual solar cells movement. The system is also capable of measuring solar cell current and voltage as well as electronically setting solar cell load, which enables measurement of I-V characteristics.
Photoresistors are used for automatic tracking of the sun. Photoresistors values must be within a certain range. If measured values are not within range, the system begins with position correction. The movement of the structure is done with the help of stepper motors and gears. Although the stepper motors have sufficient torque by themselves, self-locking gears are added to allow the motors to be completely disconnected from power to save energy. The measurement of the I-V curve is performed by the analog inputs of the microcontroller, as their resolution is sufficient and an external high accuracy measuring device is not required.
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