The 2025 RE+ Show has concluded, but its popularity is still rising. Among them, two energy storage topics were mentioned more frequently than others in the conversation: the requirement for domestic manufacturing in the United States and the race to increase energy density.

Of course, many other topics are being considered and discussed, such as the "safe harbor" eligibility of projects using Chinese equipment and the data center-driven load growth phenomenon.

We look forward to exploring these topics and more in our coverage over the coming weeks, but it’s perhaps worthwhile to first examine what these two overarching issues might mean for the U.S. market.

Energy storage system manufacturers are touting their local production capabilities.    

According to John Zahurancik, president of the Americas for Fluence, an Arlington, Virginia-based company, the company's pioneering local production of battery energy storage systems means that "Made in the USA" has become a reality in the field of large-scale battery energy storage.

This year's RE+ conference agenda and exhibition hall sent a clear and unambiguous signal: the US market's emphasis on domestic manufacturing systems has been fully implemented.

"What we continue to do in the United States is to gradually introduce each link of the solution into American manufacturing plants to maximize the satisfaction of localization requirements," Zahurancik said in an interview with ESN.

"We now manufacture all components in the U.S., from chassis, modules, HVAC, cooling systems, brackets, to system integration—it took us quite some time to complete the entire supply chain."

Despite facing capacity ramp-up delays, which the company cited as the main reason for a recent $100 million reduction in fiscal 2025 revenue guidance, CEO Julian Nebreda said on the earnings call that this was largely due to "typical" issues with new factory startups.

Fluence also announced the start of production at its 35GWh battery energy storage system assembly plant in Vietnam, which will supply its latest SmartStack solution to other global markets. These international markets account for approximately half of the system integrator's total projects.

Zahurancik noted that while Vietnam is seen as a low-cost base for high-tech manufacturing, tariffs and shipping costs preclude using the factory to supply the U.S. market — which makes up the other half of Fluence’s customer demand.

At the exhibition, all companies with current or near-term delivery capabilities, as long as their battery energy storage system solutions can meet US localization requirements and pass the "Foreign Entity of Concern" (FEOC) review threshold, highlighted this core information in their booth displays .

In Fluence's case, the battery storage system chassis are manufactured in Arizona, the battery modules are manufactured in Utah, and the Texas factory is responsible for the HVAC and thermal management system - all components come from the company's own factories.

But as Zahurancik acknowledged, the real challenge lies in the battery segment. Battery costs account for approximately half of capital expenditures, and therefore present the greatest risk for "foreign entity of concern" compliance. Fluence sources approximately half of its battery cells domestically (AESC's Tennessee plant), but still relies on Chinese suppliers for nearly half.

Samsung SDI , meanwhile, became the latest vertically integrated South Korean lithium-ion battery manufacturer to announce the production of battery energy storage systems in the United States. The company unveiled two new products at the show, including an 8.93MWh containerized lithium iron phosphate solution, which will be available in 2026 and 2027. Samsung SDI's move follows LG Energy Solution, which has already begun production of lithium iron phosphate energy storage batteries at its Michigan plant, and SK On, which also plans to start production of lithium iron phosphate energy storage batteries at its plant by the end of this year.

South Korean companies are leveraging two major advantages: First, they have a first-mover advantage gained through investments in electric vehicle battery production lines, which can be converted to produce batteries specifically for energy storage.

For other market participants, the speed and scale of new capacity commissioning remain uncertain. In particular, new lithium iron phosphate plants by startups like KORE Power and Freyr Battery, and even some projects by established companies like LG Energy Solution, have been canceled or suspended. While Chinese companies may be able to complete a number of key projects over the next two to three years using "safe harbor" provisions, it seems unlikely that they will be able to contribute significantly and sustainably to the market.

Energy density and battery size and refinement

From the perspective of technological trends, the claimed capacities of many battery energy storage system chassis at the exhibition were also eye-catching. Their energy density far exceeded the 5MWh capacity benchmark for a standard 20-foot container, which was considered the new industry benchmark about a year ago.

Accurately assessing the evolution of energy density benchmarks presents a twofold challenge: First, the latest solutions from many companies (such as Fluence's 7.5MWh SmartStack and CATL's 9MWh TenerStack) have surpassed the standard 20-foot box format;

The second is that, as is often the case with new product launches at trade shows, some of these products are not yet widely available in the U.S. market, or have actually not yet entered mass production in any market.

Despite this, the trend toward increasing energy density, from the battery to the system level, is clear. The use of large-capacity batteries exceeding 600Ah, or even 1000Ah (such as Haichen Energy Storage's latest product), is becoming the core technological path to achieving this breakthrough.

"Increasing energy density helps reduce costs," said Brian Hayes, CEO of Key Capture Energy, a developer, owner, and operator of battery energy storage systems. Hayes added that Key Capture Energy is excited about the trend.

Of course, the resulting issues concern the supply chain and battery sourcing, which Hayes noted stems from the critical role batteries play at the heart of every system and the high proportion they ultimately represent in total capital expenditures.

Adam Bernardi, director of renewable energy development at Burns & McDonnell, an engineering and general contracting firm, followed up on this topic by noting that the proliferation of non-standardized specifications makes direct comparisons between systems more difficult.

“I think the market will ultimately converge to a few energy density specifications, one reason being to make it easier to effectively evaluate each product and allow owners to switch between options seamlessly – or as seamlessly as possible,” Bernardi said.

As we’ve heard in previous articles on the topic (including perspectives from Bernardi and his team), industry players must consider logistics alongside other factors in the race to increase energy density.

"The transportation of containers to the project site and the lifting and placement of the containers will limit the size and density of the solution . Another factor to consider is the size of the foundation – while not a major cost driver, the heavier the solution, the more steel and concrete will be required to support it."

"Then there's insurability, which is closely tied to bankability. Insurance companies place great importance on the concept of maximum possible loss, so the larger and more densely populated the project, the greater the potential loss and the number of megawatts involved, and the correspondingly higher risk."

Bernardi said these financing and insurance considerations may outweigh the aforementioned physical limitations, noting that fire protection strategies and solutions for different cabinet sizes "will be crucial."

"It's all about risk mitigation and balancing all the factors."

Still, Bernardi agrees with Key Capture Energy's Brian Hayes that there are good and exciting reasons for the energy density race.

Bernardi pointed out that the increased energy density leads to a smaller project footprint, which not only means lower construction costs, but also means that some project sites that were originally unfeasible due to the need to use low-energy-density energy storage containers will become feasible.