Solar energy is one of the most important renewable energy sources. Photovoltaic (pv) cell systems are used to convert solar energy into electricity. Pv systems are divided into two groups as fixed and tracking systems. The fixed systems are mounted at a certain tilt with horizontal to make full using of sunlight. The tilt angle of pv arrays in a fixed system depends on the location and time. If this tilt angle is determined well, the amount of insolation and energy that is generated increases. When a stand-alone pv cell system is being chosen, certain design operations should be implemented. The number of modules and batteries needed for any system should be calculated by means of the amount of load, insolation level, module characteristics, etc. The design of system is finalized by Matlab software program according to the energy demand.