The Stand-alone Photovoltaic System (SAPS) should be sized optimally since there no steady backup supply connected to it. An optimally sized SAPS should have a low overall cost without compromising the reliability of the system. This paper presents the review of the microgrid and the sizing of the SAPS. The review includes seven type of sizing methods for the microgrid. The sizing of the SAPS combines the Loss of Power Supply Probability (LPSP) and Life Cycle Cost (LCC) using the Iterative Method to determine the optimal size for the SAPS. The reliability of the SAPS is further improved using the Reliability Improvement Method (RIM). The location for the SAPS is at FKE Building, UTM, Johor. The results obtained using the RIM are compared with the results obtained from the LCC Method and the GCM. The GCM does not consider the overall cost of the SAPS throughout the lifetime of the system. The LCC Method consider the overall cost for the SAPS but the LPSP is fixed at 0.812%. While the proposed RIM improves the reliability of the SAPS up to 77.8% from 0.812% LPSP with only 4.9% cost increases.