One of the most promising source of renewable energy is the direct conversion of solar energy owing to the present state of achieved technology in manufacturing PV modules, their comprehensive cost and the high depletion in non-renewable energy sources. The reliability of stand alone PV systems becomes one of the major trends in the present design of such systems. The system configuration plays an important factor determining the overall system reliability. This paper emphasizes the existing manufactured modules and illustrates the reliability analysis of different system configurations. AC bus level connection using module integrated inverters vs. DC bus level connection, cabling losses shading effects are also examined. A case study is selected to calculate and compare the reliability of different system configuration using the analytical approach.