At Stem, our people are our power – literally. Their deep expertise and collaborative mindset enable them not only to build projects, but also to build trust, foster partnerships, and inspire confidence every step of the way.
In this new series, The People Who Power Stem, we’re spotlighting the people who guide clients through the complex world of battery energy storage systems (BESS), from initial conversations to long-term performance.
To kick things off, I sat down with Todd Tolliver, Director of Development and Engineering Services, and Corey Davison, Head of Procurement and Integration Services, to get their take on the most pressing issues and evolving dynamics in the world of energy storage.
Meet Todd and Corey
Todd Tolliver brings over 23 years of renewable energy experience to Stem. He began his career in solar panel manufacturing at GE, and later co-founded NexESS Analytics – a consulting firm focused on supporting energy storage developers – with future interviewee Sean Halloran. Together, they helped clients strategize critical aspects of developing, owning, and monitoring BESS projects. Today, Todd guides Stem’s clients through interconnection applications, design strategy, early-stage development planning, and more.
Corey Davison leads Stem’s procurement advisory services. With a background in lithium-ion technology across the automotive and energy sectors, Corey helps clients evaluate technical trade-offs, assess risk, and optimize procurement strategies in a fast-moving, high-stakes environment.
Together, they partner with clients during the critical, early stages of development, helping to clarify goals, define strategy, and bring structure to complexity. Whether it’s refining a timeline, weighing tradeoffs, or navigating technical hurdles, Todd and Corey lead with an unwavering commitment to delivering solutions that work, not just on paper, but in the real world.
What Clients Often Miss
When asked about overlooked challenges in early-stage development, Todd highlights three recurring hurdles:
- Land acquisition
- Interconnection
- Revenue modeling
While all three are familiar to seasoned developers, one in particular continues to dominate the landscape. “Interconnection has been a persistent pain point,” Todd says. “Independent System Operators (ISOs) and utilities are slow to move projects through their processes, and the costs are unpredictable, which makes understanding project feasibility a real challenge.”
This is especially true in markets like PJM, where permitting is slow and competitive. In contrast, ERCOT stands out for having clearer market rules and a faster queue.
Another area developers sometimes underestimate is how uncertainty around incentives and tariffs can affect a project’s long-term viability.
“You have to assume uncertainty,” Todd explains. “Strong developers are running scenario analyses, asking what happens if an incentive goes away in five years, or even tomorrow. If the project only works in a best-case scenario, it’s probably too risky.”
Corey sees a similar trend in procurement, where policy shifts like new fire safety codes and tariffs are forcing developers to adjust how and where they source battery systems.
“Authorities Having Jurisdiction (AHJs–entities that enforce building or safety codes, such as the Public Utilities Commission, fire departments, and electrical inspectors) in places like California are now requiring large-scale fire testing,” Corey notes. “It’s raised the bar for OEMs and increased costs, delaying or even halting projects in some cases.”
Selecting the right OEM is imperative, as you’ll want to ensure they have the resources to meet these new requirements. Doing so will save you time, money, and headaches now and throughout the lifetime of your project.
Inside the Technical Evaluation
A critical step in any project’s development is understanding how it will make money and how to protect against risk. For Todd, that means thoughtful modeling with support from both internal teams and third-party advisors.
“Most developers have some in-house modeling capacity, but they’ll still look for outside input to validate assumptions or bring in a broader market view,” he says. “Ultimately, they want to understand how sensitive the project is to different policy, prices, or interconnection scenarios.”
On the procurement side, Corey focuses on use case-driven evaluations. Questions like “Is this system AC or DC-coupled?” or “What revenue streams are you targeting?” shape what vendors and technologies are viable for the project.
He also emphasizes that technical performance isn’t just about the product, it’s about the partner.
“LFP [lithium-iron-phosphate battery] is a widely adopted chemistry now, with many vendors converging on similar cell formats. With product differentiators becoming increasingly limited, what really matters is how prepared the vendor is to handle issues,” Corey says. “We’re looking at their commissioning timelines, mean time to repair, ticketing systems, and spare parts strategy. Downtime can destroy project returns, so remediation capabilities are just as important as product specifications.”
Taken together, these approaches underscore a key point: building a profitable, resilient energy project isn’t just about selecting the right equipment, it’s about making smart, informed decisions about project feasibility and your partners’ capabilities. If you want your asset to operate successfully for 20 years, you need to ensure everything is aligned from day one.
Real-World Application: Navigating Procurement Paths
One of the decisions clients often wrestle with is whether to procure batteries directly from OEMs or work with channel partners.
Corey breaks it down like this:
- Large, front-of-the-meter (FTM) and transmission connected projects typically benefit from direct OEM contracting due to cost savings. However, these cost savings come with the additional risk of coordinating with third parties for integration, deployment, and operations.
- Smaller, behind-the-meter (BTM) and distributed-generation projects often benefit from channel partners, as they can often dedicate more time to smaller projects. Channel partners are also more likely to bundle the equipment with other services, such as energy management systems (EMS); engineering, procurement, and construction (EPC); and/or operation and management (O&M).
“The strategy doesn’t have to look the same for everyone,” Corey notes. “Some teams want to procure themselves and can benefit from focused advisory input. Others prefer more of a turnkey model. What matters is aligning the support to the project’s needs.”
What to Watch Next: Trends in Tech and Policy
So, what trends are shaping the next 1 to 2 years of battery storage development?
For Corey, the tariff environment is a major short-term concern, but not a permanent roadblock, and he sees signs of stabilization ahead.
“We’re already seeing OEMs planning U.S.-based production in 2026,” he says. “That’ll help ease supply chain pressure. And even now, cost-sharing models are softening the blow of tariff hikes.”
He’s also keeping an eye on alternative chemistries, such as zinc bromide, solid-state, and sodium ion. These offer potential safety and cost advantages, particularly in fire-sensitive markets.
Todd adds that community engagement before the project is even in the ground along with proactive permitting strategies are becoming more critical than ever.
“Understand the permitting landscape early; know what the local fire codes say; talk to the community. If you show up informed and open, you have a much better shot at getting that project off the ground and doing it on time.”
We know that battery storage is an essential aspect of the energy transition and will play a critical role in meeting increased global energy demand. While there are short-term hurdles arising, the longer-term benefits, both environmentally and financially, continue to far outweigh them; so, don’t let these challenges slow you down!
What Powers You
Before we wrap each interview, we like to ask one final question: What powers you?
It’s a chance to hear, in their own words, what drives their work and why they choose to keep showing up in the renewable energy industry.
What powers Corey?
“Grid modernization is imperative for future growth and innovation in the U.S. I believe the future involves deploying DERs [Distributed Energy Resources] closers to load, and I’m continually inspired by the innovations in technology that enable that future.”
What powers Todd?
“I’m driven by the delivery of support for our clients, which helps make them more successful. Helping them navigate complex technical challenges, augment their capabilities, and enabling them to move farther downstream in project development is very fulfilling.”
Final Thoughts
As Todd puts it, “If realizing an energy project were easy, everyone would be doing it.”
That’s where The People Who Power Stem comes in: offering insight, strategy, and deep technical knowledge to navigate a fast-changing market.
Stay tuned for the next edition of The People Who Power Stem, where we’ll dive into revenue modeling and market advisory with Poorna Mujumdar and Spencer Strandholt.
