Orientation of solar photovoltaic panels in desert regions

Abstract

This research project concentrates on the design and control of a two-degrees-of-freedom orientation system for the photovoltaic solar panels in sunny regions which are considered very rich in solar energy. A brief background on the sun path and behavior at Latitude 31° as an example is discussed to help in the calculations of the needed angle ranges. The orientation system calculations are based on astronomical data and the system is assumed to be valid for any region with small modifications. The system is designed to control the Altitude angle in the vertical plane as well as the Azimuth angle in the horizontal plane of the photovoltaic panel workspace. The mechanical design is a simplified one using rotary joints and DC motors. This orientation system is expected to save more than 40% of the total energy of the panels by keeping the panel’s face perpendicular to the sun. This percentage is assumed to be lost energy in the fixed panels. The dynamics of the panel behave like a low-pass filter which facilitates the job of the controller that behaves as a good vibration isolator passing the orientation torques at low frequency and attenuating the high frequency disturbance signals coming from the surrounding environment. Point to point open-loop control is proposed in this mechanism to ensure intermittent motion when tracking the sun. To solve the problem of cloudy days, closed-loop control can be added to the system by using solar tracking sensors and feedback control loops. A special care should be taken to the design of the grid arrangement of panels in the collecting plant. The distance between two panels has to be twice the dimension of the panel to avoid the problem of shadow when the sun is inclined not only in the morning but also in the afternoon hours. A specific architecture and arrangement of panels in the collecting grid is proposed at the end of the document.