The growing need to reduce dependence on fossil fuels has accelerated the global energy transition through sustainable energy sources. However, the intermittent nature of some renewable energy sources poses significant challenges in terms of continuity and reliability. In this context, energy storage technologies are emerging as key solutions to address these challenges, prompting companies to innovate their business models (BMs) in order to enhance competitiveness in a rapidly evolving market. The purpose of this study is to analyze how the leading players in the Battery Energy Storage Systems (BESS) sector are innovating their BMs and whether Cross-Industry Innovation (CII) dynamics are emerging in the process.