This paper presents a model that computes the payback period of photovoltaic systems with battery storage (PVBS). The model, termed SPPEEDI (SAIDI Payback Period Evaluation for Extended Duration Interruption), incorporates savings from avoided business interruption with utilization of PVBS. While the PVBS system can produce clean energy and maintain energy continuity, its prohibitive cost of installation is a barrier to widespread adoption. By using the SPPEEDI model and incorporating avoided business interruption in evaluating PVBS payback periods, the model allows for a more accurate estimate of the return on investment for PVBS. This analysis identifies key grid outage thresholds where commercial PVBS could be a better investment than conventional photovoltaic systems.