AC vs DC-Coupled Battery Energy Storage: Technical & Commercial Comparison

This master's thesis provides a comprehensive technical and commercial comparison of AC-coupled and DC-coupled battery energy storage systems (BESS). As renewable energy sources increase and conventional plants retire, BESS becomes crucial for grid stability and managing intermittent generation. The study examines power train configurations, components, and applications, highlighting key differences between the two coupling methods. AC-coupled systems offer simpler design, component centralization, and lower operational costs, functioning standalone or co-located with renewables. DC-coupled systems, typically integrated with photovoltaic plants, enable more efficient solar energy capture but involve higher operational costs due to decentralized layout and complex shared converters. Through real-world examples and commercial product analysis, the thesis evaluates economic and technical considerations. Findings indicate that the optimal choice depends on project-specific needs, market conditions, and regulatory frameworks. The work concludes that future technological advancements and cost reductions are expected to balance the commercial attractiveness of both configurations, emphasizing the importance of application-specific system design.