72 Battery Enclosures for the China Three Gorges Haixi High-Voltage Direct-Connected Storage Project
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Project Overview
China Three Gorges is building a high-voltage direct-connected storage plant at a high-altitude site in Haixi, Qinghai, with the storage system supplied by NR Electric. ETENZ manufactured the 72 battery container enclosures for the plant, together with every battery-cluster steel frame that goes inside them. The contract runs through Changzhou Bori Electric Power Automation Equipment Co., Ltd., NR Electric's primary power equipment manufacturing base. In a high-voltage direct-connected system the battery clusters are cascaded through power units and tied straight onto the medium-voltage bus, which removes the line-frequency step-up transformer from the chain. That topology rewrites the brief for the enclosure. The floor carries rows of insulating support pedestals, the upper and lower battery frames are isolated from each other, equipotential earthing is resolved tier by tier, and the clearances inside are wider than a conventional storage enclosure needs. The shell stops being a box that holds equipment and becomes part of the insulation coordination. The first enclosure passed first-article review in June 2026 and the first batch shipped in late July 2026, with the remaining units following in rolling batches.
Service Scope
Enclosure fabrication and internal structural steelwork
ETENZ's scope on this project is the battery container enclosure itself, the battery-cluster steel frames inside it, the distribution boards and the primary and secondary earthing bars, and internal structural items such as drip trays and rodent barriers, together with the installation and interface work inside the enclosure for owner-supplied equipment including post insulators, insulating beams, chillers, air conditioners and airflow agitator fans. Battery modules, power units and energy storage system integration sit with NR Electric.
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Engineering & Integration Points
Insulation coordination built into the structure
In a high-voltage direct-connected enclosure the battery clusters no longer sit on the floor. They stand on rows of insulating support pedestals, the upper and lower frame tiers are separated by insulation, the frame tops carry the mounting structures for post insulators, and insulating beams with pipe clamps support the underside of each cluster. Every one of those interfaces was locked down at the drawing stage, so no insulator fit-up tolerance was left to be worked out on site.
A non-standard body wider than an ISO container
This is a 12-metre-class non-standard enclosure whose width goes beyond the ISO container cross-section, so neither the standard container underframe nor its lifting practice could be carried over. The base frame is locally reinforced to follow the battery-cluster layout, keeping the floor from deflecting once the enclosure is fully loaded. Lifting is from the bottom, with lift points positioned to suit the internal weight distribution and the lift verified for the fully loaded condition.
The enclosure builder also supplies the racking inside
Beyond the shell, the battery-cluster steel frames are fabricated and installed by ETENZ: welded square-tube main frames, support rails stiffened with formed ribs, insulation between the upper and lower tiers, earthing points on the lower frame, and powder coating on the finished frame. Tier height is a critical dimension, held tightly against the customer's 3D model so that cluster positions repeat identically across all 72 enclosures.
Sealing and corrosion protection for high-altitude outdoor duty
The enclosure is rated IP55 overall. The roof is formed with a drainage fall and sealed along its edges; all four doors run double gaskets and come with removable rain hoods, rodent guards and wind stays. External surfaces follow ISO 12944 C4. Halogen-free, V-0 rated mineral wool insulation is laid over the roof, floor and all four sides, the underside included apart from openings and the main frame weld lines. Structural design life is not less than 25 years.
First-article review before the series was released
One sample enclosure was assembled and taken through the full first-article review before series production started. Factory testing covered the bottom lift, enclosure structural strength, installation accuracy of the internal steelwork, weld quality and fastener integrity, wiring and dimensional checks, and a weathertightness check with water sprayed from every direction. The first enclosure also went through a whole-unit rain test to reproduce the way rainwater accumulates over long service.
Delivery Value
The first enclosure passed first-article review in June 2026 and the first batch shipped in late July 2026; the remaining units follow in rolling batches.
Project Value
An enclosure for a high-voltage direct-connected system cannot be copied from a conventional storage enclosure. Insulator mounting positions, frame tier heights and earthing points all have to be settled once, at the structural drawing stage, because reworking them on site costs far more than solving them in the factory. On this project the full general-assembly and production drawing set was reviewed jointly before the series was released, and one sample enclosure went through first-article review first. That turned insulation fit-up, frame tolerances and the installation sequence for owner-supplied items into a repeatable process, so all 72 enclosures could roll out against a single standard.
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Battery Energy Storage System Prefabrication Solution
For storage and renewable projects, ETENZ delivers prefabricated enclosures with power, thermal, fire, security and monitoring interfaces, factory pre-tested to cut build time and support phased expansion and OEM/ODM.
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