How Big Should a Battery Be? The Answer Depends on Where You Build It.
Article by Ryan Mone, Principal Power System Engineer; RLC Engineering
For battery developers, choosing a project size and an interconnection location are closely linked decisions. A larger battery may offer more revenue potential, but the return from adding capacity can vary substantially by site. RLC recently completed a generator screening study comparing battery energy storage system (BESS) sizes at seven candidate interconnection locations in the ISO New England (ISO-NE) market. Using production cost modeling and market dispatch simulations, we evaluated battery power ratings from 25 MW to 250 MW and estimated annual energy market revenue for each location. The goal of screening is to narrow the options early. It helps developers identify which site and battery size combinations merit the time and expense of detailed engineering, interconnection, and economic studies.
What The Analysis Revealed
Each location had a different revenue curve. At some sites, estimated annual revenue continued to rise as battery size increased. At others, the additional revenue from a larger battery began to taper off. One location showed a substantial decline in estimated annual revenue at 250 MW. These differences show why the largest battery is not automatically the strongest development option. Comparing sites and sizes side by side gives developers a clearer basis for deciding:
Which interconnection locations warrant further investigation?
What battery size should be evaluated in more detailed studies?
Where does adding capacity produce diminishing revenue returns?
A Clearer Starting Point for Development
Generator screening studies help developers compare potential locations and BESS sizes before committing significant time and capital to detailed engineering, interconnection, and financial analyses. By narrowing the field to the most promising candidates, developers can focus their resources on the opportunities that warrant a closer look.
For this study, RLC compared seven locations across a range of battery sizes, identified promising site and size combinations, and highlighted where adding capacity produced diminishing revenue returns. The findings provide a more informed starting point for site selection and sizing.
Screening is an early step in the development process. Interconnection costs, project costs, technical requirements, and other potential revenue sources still need to be evaluated before making a final investment decision.
Evaluating BESS opportunities? Connect with RLC Engineering to discuss how a generator screening study can inform your site selection and sizing decisions.
