The success of every battery energy storage system (BESS) project goes far beyond development and installation. The true challenges–and opportunities–lie in operationalizing and monitoring these assets over their lifecycle to optimize performance, increase reliability, and ensure financial returns meet pro-forma expectations.

In this article, we shine a spotlight on two of Stem’s experienced leaders: Sean Halloran, Director of Performance & Operations, and Katie Strebe, Performance Engineer. Together, they share insights on common pitfalls when transitioning a project from development to operation, the keys to monitoring your BESS assets, and what the future holds for BESS performance engineering.

What Gets Overlooked in the Transition from Development to Operations

Sean explains a recurring challenge many clients face: “Developers typically focus on a few[TL1.1] key areas, like financing, land acquisition, or permitting, but very few have deep operational expertise to fall back on.” This gap means that when a project transitions from development into operations, there’s often a steep learning curve.

“Many developers underestimate the effort and resources required to successfully commission and operate a battery project,” Sean says. “It’s not just a ‘set it and forget it’ asset. There’s a lot involved technically and logistically that doesn’t always come up until the asset is live.”
Katie echoes this, pointing out the difference in priorities: “Developers focus on getting to commercial operation date (COD), but asset owners need to think long-term…tracking performance, identifying degradation, and planning for end-of-life well in advance.”

This long-term perspective is crucial because, as both Katie and Sean highlight, the idea that storage systems are a hands-off asset is a common misconception. “For large-scale projects, you need a team of dedicated operations and monitoring (O&M) personnel,” Sean shares. “Some clients are surprised when they hear a 300 MW project may require ten full-time staff for operations and maintenance when they were expecting to only hire one. It’s a daily, ongoing effort that needs dedicated personnel who are well-versed in the batteries and their health.”

For behind-the-meter (BTM) assets, Katie adds, “The smaller the asset, the more critical early detection becomes because any failure has a proportionally bigger impact on performance and revenue. Think of it this way: if you have a site with 45 DC blocks and one goes down, it’s not the end of the world. But if you have a BTM site with only two DC blocks and one stops working properly, it would have a much larger impact.”

How to Keep Things Going Smoothly

When it comes to commissioning, Sean stresses one thing above all else: data. “A smooth commissioning process happens because planning was in place, expectations were understood, and decisions were backed by data early and often.”

He points out common pitfalls like extended timelines caused by insufficient preparation, especially around testing. “Sometimes clients don’t realize they’ll need special equipment, like load banks rented months in advance, to perform grid compliance tests. Not planning for these details can lead to costly delays.”

This is why it’s important to have the right team. “The commissioning process can often involve various people, companies, and technologies all having to work together,” Katie remarks, “having a team that can communicate well with each other and understand their roles to make the asset perform is the only way to get through the hurdles that will inevitably come up.”

Katie also adds that clear performance monitoring is vital once commissioning wraps up. “Key performance indicators (KPIs), like round-trip efficiency, state of charge (SOC), temperature profiles, and degradation rates, should be tracked regularly. These help flag potential issues early before they escalate.”

Regardless of the operational challenges that may arise, many problems can be avoided with the right monitoring and detection systems in place. Katie explains, “Frequent performance reviews can reveal subtle trends that indicate issues, such as SOC drift, inverter inefficiencies or thermal management concerns.” Sean adds, “Expectations need to be realistic and backed by data-driven insights. That’s what enables efficient operations and maximizes the asset’s lifespan.”

End of Life Strategies and What’s Next

Looking ahead, Sean highlights an emerging focus for asset owners: planning for end-of-life scenarios and augmentation strategies. “Degradation is inevitable, but with detailed operational data, you can forecast when augmentation or replacement might be necessary– sometimes earlier than you originally planned.”

He notes the complexity this introduces, especially with evolving battery chemistries and OEM (original equipment manufacturer) support. “Some early projects used chemistries no longer produced, so sourcing parts or performing augmentation six or seven years down the line can be a challenge; especially, because you can’t necessarily buy ahead for it. For example, if you needed 10 batteries for your site but bought 13 because you knew that you wanted to augment at Year 6, those extra three batteries will degrade just by sitting in a warehouse.”
The challenge of planning for the future with limited foresight into evolving technologies has prompted the industry to rethink end-of-life strategies.

Katie adds that sustainable options like recycling and second-life applications are gaining traction. “The industry is increasingly looking at circular economy approaches by recovering valuable materials and repurposing batteries to extend their useful life. Depending on the manufacturer, they will even come to your site and pick up the old batteries for you, leaving the existing infrastructure to possibly add new battery cells on top and start the process over again.”

When a new project comes online, it may seem like 15 or 20 years is a long way away, but you’ll get there quicker than you think. Consider your options early and get creative–batteries are still a relatively new technology, so there aren’t many examples of end-of-life strategies. You may have more options than you know.

Advice for New Asset Owners

Sean’s advice is straightforward: “Don’t let your data sit on the table. Use it. Collect it early and often. Keep iterating with it. Compare performance against your pro-forma and adjust your plans accordingly.”

While she recognizes the importance of thoughtfully using your data, Katie encourages owners to build strong partnerships with their services and O&M teams. “Successful operations require collaboration, clear communication, and ongoing vigilance.”

What Powers You

Finally, when asked what drives their passion in this industry, they remarked:

Katie: “My motivation comes from seeing how energy storage can transform the grid, making it cleaner, more resilient, and more flexible. I’m energized by the problem-solving aspect for our clients and being part of a team that ensures these projects deliver real impact.”

Sean: “I believe renewable energy is a crucial part of the world’s energy mix. What powers me is helping solve the complex challenges of the energy transition by applying new technologies, understanding market dynamics, and enabling these assets to succeed.”

Conclusion

At Stem, experts like Sean and Katie are the backbone of operational excellence, ensuring each BESS project not only powers communities today but continues to adapt and thrive well into the future.

Come back next week where we’ll continue to learn about monitoring and operating BESS assets from more incredible members of our team!