While the number of distribution-connected PV units has been on the rise in recent years in the United States, the short-term fluctuation of PV output remains a challenge to continued growth and adoption. This paper explores the battery energy storage requirements for mitigating PV output fluctuations. The behavior of irradiance fluctuations is examined for a full year to determine the power rating, capacity, and cycling requirements of the battery energy storage system. Several sensitivity analyses are performed on solar ramp rate limits and battery power rating to uncover the characteristics of solar irradiance fluctuations and identify the potential solutions for reducing the battery energy storage system requirements.