Standalone BESS comparison highlights the long-term value of string architecture

With a combined capacity of more than 1 GW/2 GWh, the ten projects entered operation within the same period under highly comparable operating conditions. Located within Ningxia’s northern renewable energy corridor, they share similar climate conditions, grid dispatch requirements, electricity market rules and capacity compensation mechanisms, with operating data normalized on a per-100 MWh basis. Against this largely consistent operating backdrop, system architecture becomes the defining variable, with the projects collectively representing the industry’s two dominant utility-scale storage approaches: conventional centralized PCS and string PCS.

This comparison is particularly relevant as standalone battery storage becomes increasingly market-driven. In Ningxia, where renewable energy accounts for more than half of installed generation capacity, standalone BESS increasingly relies on electricity trading, capacity payments and ancillary services for revenue, making long-term operational performance an increasingly important driver of project economics.

More than 41 months after commissioning, the projects have accumulated sufficient operating data for meaningful long-term comparison. To minimise the influence of early commissioning and changing market conditions, the analysis focuses on the most recent 17 months of operation, providing a more representative assessment of long-term operational performance.

Among the ten stations, Tongli No.2 Energy Storage Station, equipped with JDEnergy’s string-based BESS, delivered the strongest overall operational performance. During the evaluation period, it discharged approximately 4.9 GWh more electricity than the station ranked eighth, creating greater revenue opportunities. It also ranked first in cumulative energy throughput, recorded 1,768 utilization hours, led monthly utilization in eight of the 17 months, and maintained a stable round-trip efficiency of approximately 89%.

The results demonstrate how system architecture can directly influence long-term operational performance. By dividing the system into independently controlled battery strings, the string architecture minimizes weakest-link constraints and eliminates DC circulating current losses, allowing more installed capacity to remain available for dispatch. Independent control also enables each battery string to operate across its full usable state-of-charge range, while millisecond-level fault isolation keeps unaffected units online during maintenance. Together with optimized thermal management, these

capabilities support system availability above 99.9%, preserve cumulative energy throughput and maximize dispatchable energy throughout the asset’s lifetime.

The Ningxia comparison highlights a broader shift taking place across the battery storage industry. As standalone BESS increasingly depends on revenues from energy trading, capacity payments and ancillary services, long-term project value is becoming more closely linked to operational performance than installed capacity alone. While project economics are influenced by multiple factors, the comparable operating environment across the Ningxia projects provides rare field evidence that system architecture can have a measurable impact on energy throughput, availability and long-term returns. For developers and asset owners, architecture selection is increasingly becoming a strategic decision that shapes lifecycle project value rather than simply an engineering choice.