The global battery energy storage sector surpassed 100 GW of annual installations for the first time in 2025, marking a significant milestone for the industry, according to Wood Mackenzie’s inaugural Global Battery Energy Storage System (BESS) Integrator Comprehensive Ranking.
The report evaluates suppliers of AC-integrated battery energy storage systems (BESS)—factory-assembled solutions that combine battery cells, power conversion systems (PCS), battery management systems (BMS), thermal management, and control systems into a single AC-connected product.
According to the ranking, Sungrow secured the top position as the world’s leading BESS integrator, followed by Tesla in second place and CATL in third. BYD ranked fourth, while Envision and Trina Storage shared fifth place. Fluence, LG, Canadian Solar, and Wärtsilä completed the global top ten.
Wood Mackenzie said the ranking reflects the evolving procurement priorities of utilities, independent power producers (IPPs), and project developers, who are increasingly assessing suppliers based on their ability to deliver projects across the entire lifecycle rather than focusing solely on technology performance.
The assessment evaluated companies across ten criteria, including technology maturity, research and development, safety, vertical integration, supply chain resilience, environmental, social and governance (ESG) performance, financial strength, and execution capability.
According to the report, six of the global top ten integrators have more than a decade of experience in battery storage integration, highlighting the growing importance of engineering expertise, commissioning capabilities, and long-term operational performance as energy storage projects increase in scale and complexity.
The report also found that every company in the global top ten manufactures at least one critical system component—such as battery cells, power conversion systems, or battery management systems—supporting greater vertical integration, improved quality control, and reduced project execution risks.
Wood Mackenzie noted that eight of the top ten companies exceeded its benchmarks for system efficiency and lifetime cycle performance, while nine invested more than 4% of annual revenue in research and development during 2025. Additionally, nine companies reported positive profitability, strengthening confidence in their ability to support long-term warranties and service commitments.
Beyond the top ten rankings, the report awarded Grade A status to 24 manufacturers, reflecting the continued maturity of the global battery energy storage industry and the increasing number of suppliers meeting stringent technical and performance standards.
The report also highlighted that leading BESS suppliers are expanding their manufacturing footprints across global markets to address evolving trade policies, localisation requirements, and supply chain considerations while maintaining internationally recognised safety standards and advanced thermal management technologies.
Timothy Shen, Senior Research Analyst for Solar Supply Chain at Wood Mackenzie, said battery storage is increasingly being viewed as critical infrastructure, with buyers placing greater emphasis on execution certainty, financial resilience, engineering capability, and long-term service support as projects are expected to operate for decades.
Wood Mackenzie publishes the Global BESS Integrator Comprehensive Ranking annually, evaluating suppliers of AC-coupled battery energy storage systems based on their performance during the previous calendar year.
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