Photovoltaic Panel Auto-Tracking Soluton

Photovoltaic (PV) conversion is one of the most important applications of renewable energy sources because of the direct conversion of solar energy to electric energy. Although PVs are more expensive compared to other types of energy converters, they have some advantages such as low weight and feasibility of small scales. Therefore, it is important to absorb the maximum solar energy in order to increase the efficiency of the energy converter. Levels of efficiency achieved in modern production are 14%-17% for monocrystalline silicon, 13%-15% for polycrystalline silicon and 5%-7% for amorphous silicon. Because of the daytime motion of the sun, as well as of the seasonal trajectory differences, sunlight always radiates under some angles or indirectly on solar arrays. Furthermore, some part of the light is reflected from the surface of the solar cells. Both circumstances result in incomplete absorption of the solar energy. One method for increasing the output electric energy of PV converters is by using solar tracking. This is done by implementing technologies allowing PV arrays to follow the sun continuously in daytime so sunlight can be radiated to solar cells directly where maximum electric energy can be generated. A comparative study discusses typical increase of power characteristics by employing solar tracking, and this paper proposes an affordable yet efficient biaxial tracking solution to achieve that. The solution is a cheap PIC based embedded design calculating next optimal spatial orientation by using a 4x-LDR (light dependent resistor) sensor, and tracking that optimal orientation with a two-degrees of freedom stepper drive.