Analysis of Electrical Losses and Cost Optimization in Hybrid Parks

Sammanfattning

The ongoing transition toward renewable energy has accelerated the deployment of utility-scale photovoltaic (PV) power plants. As PV systems increase in size, design decisions related to inverter topology, electrical layout, and battery energy storage system (BESS) integration become increasingly important for both technical performance and long-term project economics. In particular, the choice between string and central inverter configurations affects how power is collected, converted, and transmitted through the plant, which in turn determines where electrical losses occur. This thesis investigates the technical and economic trade-offs between different inverter configurations in utility-scale PV parks. The analysis compares string inverter configurations with central inverter configurations by evaluating cable losses, inverter losses, transformer losses, and mismatch losses. The results show that losses are distributed differently depending on system architecture. String inverter configurations generally result in shorter DC cabling and more distributed maximum power point tracking (MPPT) control, reducing mismatch sensitivity, but they may require a more extensive AC collection system. Central inverter configurations instead concentrate power conversion in fewer units, which can reduce parts of the AC-side infrastructure but increases the importance of DC-side aggregation, DC combiner boxes, and larger DC feeder cables. The results demonstrate that no single loss component alone determines the most suitable configuration. Instead, the optimal solution depends on the combined effect of cable losses, mismatch losses, transformer losses, inverter losses, and component costs. Configurations with lower cable losses do not necessarily provide the best overall performance if they are more sensitive to mismatch or require higher investment costs. The study also shows that transformer selection can significantly influence the economic outcome, particularly when integrated inverter-transformer solutions are considered. In addition, the thesis evaluates the economic impact of integrating BESS as a plant-level complement to the PV system. The results show that BESS profitability is highly dependent on future revenue streams, market conditions, and battery cost development. While conservative revenue assumptions limit the economic attractiveness of BESS, more favorable scenarios indicate that storage may become an increasingly valuable part of future PV projects.