The variability of renewable sources has high impact on power system reliability, e.g. photovoltaic (PV), and energy storage (ES) is one of several options for better grid reliability [1–3]. This paper serves to establish power system reliability of hierarchical level 1 (HL1) using analytical techniques. The IEEE Reliability Test System (IEEE-RTS) generation model and load model are applied to convolute a system risk model. Incorporating PV improves system reliability but the variability of PV power output compromises on PV capacity credit. ES is included into system risk model to enhance system reliability performance. System adequacy indices are investigated to show the system reliability performance. Impact on system generation cost, via variation of PV and ES capacities are presented. Actual Singapore PV irradiance data and Energy Market Company price information are incorporated in this study. This analytical technique can help Independent Service Operators (ISO) to evaluate the potential of PV to benefit system reliability and find ways to improve its potentials.