This study details a comprehensive storage-sizing methodology to allow a concentrating solar power plant to reliably integrate in the Cyprus power system which is classified as small and isolated. The need for providing a storage solution arises from the fact that large quantities of renewable energy sources may impose certain challenges on how isolated systems operate. Developing solutions to these challenges will enable higher penetrations of renewable generation sources on such systems and the future growth of renewable energy. To this extent, the methodology described in this study pertains to clear and explicit steps required to provide sufficient evidence toward the reliable integration of a large-scale solar-dependent plant through an appropriately sized battery energy storage system.