Int. J Latest Trends Computing Vol‐4 No. 4 December 2013 145 Automatic Irrigation System with PV Solar Tracking Basim Alsayid 1 , Jafar Jallad 2, Muhammad Dradi 3 , Ola Al-Qasem 4 Department of Electrical Engineering, Palestine Technical University-Kadoorie Tulkarm Palestine 1 b.alsayid@ptuk.edu.ps 2 Eng.jafar2012@hotmail.com 3 mohamaddradi@yahoo.com 4 bdrunola@hotmail.com Abstract— In remote rural areas in Palestine, direct access to an electric grid is almost impossible especially where utility grids are either not available or its further extension is not feasible. The availability of abundant solar irradiance, makes solar energy the most promising one. In particular, the utilization of Photovoltaic (PV) off-grid solar systems could be the solution for pumping and irrigation system. The objective of this paper is to design and construct an automatic irrigation system powered by PV panels on a laboratory level. A humidity sensor in the soil and temperature sensors in the air are used to check the need for irrigation in order to operate a pump powered by the PV system. This PV system is a two axis solar tracking one. Sensors are installed on PV panels to check the position of the sun so that PV panels are always perpendicular to the sun. This control is made by means of a microcontroller. The whole system is first simulated by ISIS simulation software to validate the final control algorithm to be implemented. A particular attention has been given to the solar tracking system. Experimental study is carried out to evaluate the performance of the tracking system in laboratory by using a light source to simulate the sun.These results show the validity of the control of the irrigation system and the PV panels are always normal to the light source. Keywords— Solar Tracking, Microcontrollers, Stepper motors, Sensors, Simulation, Automatic Irrigation. 1. Introduction Like many other countries the energy situation in Palestine is becoming critical. In order to solve this problem, the government has taken initiatives for utilization of renewable energy sources for electricity generation. One of these renewable energy sources is the photovoltaic systems because of the high daily average of solar radiation (about 5.4 KWh/m 2 -day) [5],[13,[16]. Photovoltaic systems have different applications. One of these applications is irrigation and pumping water in remote areas and far from electrical grid using PV DC water pumps [2]. DC pumps can be run by the electricity generated by PV systems while AC pumps need an inverter [10], [13]. Solar tracking keeps PV panels in an optimum position perpendicularly to the solar radiation during daylight hours so as to increase the collected energy [3]. Efficient collection of maximum solar radiation on a flat panel requires adjustment of two parameters of the energy collecting surface namely the angle of the azimuth and the angle of tilt [1],[9],[11].This paper deals with an automatic irrigation system powered by PV panels with tow axis solar tracking. Figure 1 shows the block diagram of the proposed system. It consists of Humidity sensor in the soil and temperature sensors in the air are used to control the DC water pump operation. Four light dependent resistances (LDRs) sensors are used to detect the sun position, this information is read and processed by a 16F877A PIC microcontroller to move two stepper motors, used as actuators for the two axes PV solar tracking system, in order to control the azimuth and tilt angles. The system has been simulated using PROTEUS-ISIS simulation software first as shown in figure 2, and then it is constructed as shown in figure 3. Figure 1. Block diagram of the automatic Irrigation system with PV solar tracking _______________________________________________________________ International Journal of Latest Trends in Computing IJLTC, E‐ISSN: 2048 ‐ 8688 Copyright © ExcelingTech, Pub, UK (http://excelingtech.co.uk/)