Accure Report Reveals 20% of Energy Storage Projects Fail to Meet Output Targets and Highlights Common SOC Errors

According to a recent report released by Accure, a battery health management and data analytics company based in Germany, nearly 20% of energy storage projects are failing to meet their target output capacity. The report, titled “2025 Energy Storage System Health and Performance Report“, is based on research from over 100 commercially operating energy storage systems globally, each with a capacity exceeding 10MWh. The data was sourced from an independent battery monitoring database with a total capacity of over 18GWh.

The report highlights the operational performance of energy storage systems in real-world applications, the challenges currently faced, and the positioning of industry benchmark operational standards. Some key findings include:

• 19% of energy storage systems experienced failures or issued warnings, negatively impacting operational revenue. Specific issues included system outages, recurring safety alarms leading to shutdowns, and poor battery consistency.
• The majority of systems in the industry operate with a round-trip efficiency (RTE) of over 85%, with 40% achieving efficiencies exceeding 88%.
• For every 1% decrease in RTE, the internal rate of return is estimated to drop by about 1%, potentially extending the investment payback period by up to one year.
• Most energy storage projects are over-configured by 15-25%. Configurations below 10% offer little protective benefit, while those exceeding 30% significantly increase investment risks.
• Only 83% of projects met their design capacity requirements, meaning that nearly 20% of projects failed to achieve target output capacities.

In phosphoric lithium iron (LFP) energy storage systems, a state of charge (SOC) error of ±15% is commonly observed, with outliers exceeding 40%.

Accure’s analysis over the past three months indicates that 81% of the components in battery storage systems are functioning well, while 19% are facing operational issues that directly reduce income. These issues include system trips, repeated safety alerts, and inconsistencies among batteries.

With respect to system loop efficiency, the report notes:

• The operational efficiency of most systems is generally ≥85%, with the best-performing systems sustaining an efficiency ≥88%.
• 40% of energy storage systems achieve efficiencies over 88%, 43% fall between 85-88%, and 13% range from 83-85%.

For assets totaling 200MWh, a 1% decrease in RTE could lead to a decrease in the internal rate of return of approximately 1%, potentially extending the payback period by up to one year.

Accure also reported that to prevent battery degradation and capacity loss, most energy storage projects are over-configured by 15-25%. Smaller projects (50MWh) may even see over-configurations of 30-35%, while larger installations average around 20%.

However, configurations below 10% provide minimal protection, while those exceeding 30% pose significant investment risks.

Overall, only 83% of projects met their design capacity requirements. The majority of systems have capacities exceeding their nameplate values by 0-10%, with a few exceptional systems exceeding by 25%. Furthermore, 17% of projects fell short of their targets. In SAT testing, nearly 20% of projects did not meet their target output capacity.

It’s important to note that some projects only barely met standards due to equipment over-configuration of 30%, leading to fundamentally different risk profiles compared to those that just met the requirements with minimal margins. There are also concerns that some SAT test results may be “embellished” to ensure compliance, as such superficial certification does not guarantee long-term sustainability.

Additionally, 51% of projects are experiencing delivery delays of 1-2 months, with some facing delays of up to 8 months or more. Delays in the commercial operation date (COD) not only increase costs and defer revenue but may also impact battery health.

In LFP systems, an SOC error of ±15% is common, with outliers exceeding 40%. To mitigate these risks, many operators increase safety margins, which directly reduces available capacity and revenue.

Finally, the report indicates that 20% of energy storage projects suffer from poor data quality. Currently, over 80% of battery storage systems are capable of providing stable data availability, and this trend is continuing to improve.