As global energy demand continues to rise, battery energy storage system (BESS) projects surpassing 1 gigawatt-hour (GWh) in capacity are becoming increasingly common. Multi-GWh-scale systems are critical for integrating renewable energy, maintaining grid stability, and achieving climate goals. However, projects of this size pose operational challenges. As BESS projects continue to scale, the industry requires advanced energy management software capable of controlling, monitoring, and optimizing high-capacity assets with high precision and reliability.

Intelligent Architecture for Large-Scale Operations

Intelligent software architecture that provides actionable insights and real-time visualization tools are essential for managing large-scale BESS facilities, especially as they exceed 1 GWh. In these projects, data is collected from a variety of sources—including, but not limited to, the battery modules, the BESS enclosure (chiller, fire safety system, and dehumidifier), generations assets (solar, wind, thermal), central/string inverters, as well as medium and high voltage equipment. With such a large volume of data, operators must be able to oversee operations at both macro and micro levels to maintain optimal performance both within each piece of equipment and site wide.

Imagine every light on your car's dashboard illuminating at once—how would you quickly identify and address the root cause? Now imagine that happening as you are trying to manage and operate millions of batteries and highly consequential equipment. Sophisticated software provides a holistic view of both the site and fleet operations while isolating specific issues when they arise, enabling operators to maintain system reliability and optimize performance.

Why Cell-Level Data Is Important for Asset Owners

For maximum performance, BESS operators need a line of sight into every component of their projects—down to the battery cell level. Key parameters can be observed within individual battery cells such as voltage, temperature, and current. Granular visibility enables early detection of abnormal cell conditions that should be proactively addressed. Individual cell data can also be analysed to flag weak cells and to identify cells that are driving imbalance, allowing asset owners to increase usable energy and optimize system performance. As artificial intelligence (AI) expands and becomes more widely used for anomaly detection and predictive maintenance, the value of cell-level data will only increase.

While cell-level data is extremely valuable to users, it is incredibly complex to collect, store, and analyze them at such a high granularity, especially as systems grow in size. A mature, well-architected energy management system (EMS) is required to reliably manage this volume of data without affecting site performance.

Increasing Usable Energy

One of the challenges faced by traders and BESS operators today is how to accurately estimate the amount of capacity available in the battery at any given point in time. Although this may seem like a simple calculation based on nameplate capacity and the reported state-of-charge (SoC), the reality is that the actual capacity available is based on degradation, imbalance, and the true SoC—which may be quite different from the reported SoC.

These challenges are compounded with lithium iron phosphate (LFP) batteries, where the voltage curve is relatively flat between 20-80% SoC (as illustrated in the graph above) making it harder for the battery management system (BMS) to accurately determine the SoC of the system. Further complicating the issue is that traders often prefer to keep the system between 20-80% SoC so it is available for frequency events that can occur if power generation or transmission is interrupted, and that may require quickly charging or discharging the system. As a result, many batteries spend weeks within the flat portion of the voltage curve, causing inaccuracies in SoC estimation to persist and cells to grow increasingly imbalanced.

As cells grow increasingly imbalanced, the amount of stranded energy increases and usable energy (energy the system is getting from each battery cell) decreases, leaving less available capacity for performing market operations and generating revenue.

Today, advanced energy management software can automate processes such as regular cell balancing and SoC calibration. Doing so reduces the manual labor required to sustain optimal operations and enables the system to stay in market when these actions are performed. This reduction in downtime and increase in usable energy has a significant impact on a system’s financial performance, further differentiating the long-term benefits of using sophisticated BESS software for your system.

Split-Second Response Times

For BESS owners looking to participate in increasingly sophisticated grid services and applications, reducing latency is critical. As renewables grow in prevalence, batteries are being called upon to respond to frequency events and provide natural inertia to the grid.

These capabilities are particularly vital in regions like California and Australia, where fast frequency response (FFR) is essential to maintaining grid stability and meeting market requirements. For example, Australia’s National Electricity Market recently introduced the 1-second Frequency Control Ancillary Services (FCAS) markets and associated revenue streams. Meeting these rapid response times is challenging and not a service all software providers can provide at large-scale sites.

Enabling the Next Era of Energy Storage Growth

Many existing energy management platforms were initially designed for smaller projects. The industry’s rapid growth, however, demands software that can seamlessly transition to larger operations. Wärtsilä Energy Storage & Optimisation (ES&O)’s GEMS Digital Energy Platform, for example, was originally developed to manage 1–5 megawatt (MW) sites. Now in its seventh generation, it autonomously handles a thousand times that capacity for a single site.

It is only with sophisticated software that we can unlock the full potential of multi-GWh-scale BESS projects, bringing us closer to a resilient, 100% renewable grid.