This book introduces a modular design approach with complete methodologies to evaluate the performance of stand-alone photovoltaic power system /battery storage. The optimum solar cell area and optimum tilt angle of solar cell are estimated to obtain maximum solar insolation and to avoid unwanted shading , the capacity of battery storage have been determined .The solar cell tracker has been installed by a dc motor with high torque and low speed. The output of its sensor is entered to an amplifier circuit and output of amplifier is entered to comparator to convert the signal to square wave then to clipping circuit and to obtain positive pulses. A PLC is used to count these pulses and move the solar cell by an angle, parallel to sun rays, according to this number of pulses.The output of the solar cell is converted to digital signal by analog to digital converter.The digital signal is sent to MATLAB program via parallel port.The output of the solar cell is recorded on the computer each half an hour through a MATLAB program. A proposed technique is developed and used to maximize the incident global insolation