Global Energy Storage Manufacturing Under Scrutiny as Widespread Quality and Safety Gaps Emerge—Report

A comprehensive inspection study conducted by Intertek CEA has exposed major quality and safety concerns in the global Energy Storage System (ESS) manufacturing industry. The report, based on 880 factory inspections across 90 manufacturing facilities worldwide, identified a total of 3,370 manufacturing defects. The findings have raised serious concerns for project developers, investors, and asset owners as the energy storage market continues to expand rapidly across global renewable energy sectors.

According to the report, the rapid growth of the ESS industry is putting pressure on manufacturing processes, while quality control systems are struggling to keep pace with rising production volumes. The study revealed that nearly 75% of all identified defects occurred during the system integration stage. Experts noted that this stage involves highly manual and labor-intensive assembly work, which increases the chances of errors. In many cases, weak supervision of outsourced integration companies further contributed to manufacturing inconsistencies.

The report also highlighted that frequent product upgrades and rapid design changes are preventing manufacturing processes from fully stabilizing. As a result, many complex systems are entering the market with unresolved upstream issues that could impact long-term performance and safety.

Among the system-level findings, more than one in eight inspected units showed safety-critical defects. Battery Management System (BMS) issues were identified in 4.7% of the systems inspected. Such defects can lead to failures in monitoring and controlling battery operations. Thermal management system problems were found in 4.2% of units, increasing the risk of overheating and faster battery degradation. In addition, 4.4% of the systems suffered from water ingress problems, which can lead to internal short circuits, unexpected shutdowns, and in severe cases, thermal runaway incidents.

Although cell-level manufacturing represented only 15% of the total findings, these defects were considered the most severe. Since battery cells form the foundation of an energy storage system, even small deviations during critical production stages such as electrode manufacturing and cell assembly can compromise the safety and reliability of the entire system.

The remaining 10% of the findings were linked to module manufacturing. Lower levels of automation in module assembly resulted in problems such as manual material handling errors, inconsistent welding quality, and voltage variations between cells during electrical testing.

Intertek CEA emphasized that independent and robust quality assurance measures are essential to protect the long-term operational and financial performance of energy storage assets. The report warned that relying only on manufacturer warranties is not sufficient because some defects can bypass factory quality checks due to uncalibrated testing equipment or failure to follow standard operating procedures.

To reduce these risks, the company recommended a complete end-to-end quality oversight strategy. This includes factory quality audits, real-time production monitoring, pre-shipment testing of random samples, and strict Factory Acceptance Testing (FAT). The report concluded that these preventive measures are critical to identifying and resolving defects before shipment, helping avoid costly failures, operational downtime, and serious safety incidents in the field.