Balance of Plant

E-Houses for Battery Energy Storage

An e-house is a prefabricated electrical building that is assembled and tested in a factory, then shipped to site as a complete, ready-to-connect unit. In a BESS project it packages the medium- and low-voltage equipment that links the batteries to the grid into a single transportable module, cutting on-site electrical work and shortening the schedule.

E-Houses for Battery Energy Storage

On a large battery plant, the equipment between the DC blocks and the grid connection point has to sit somewhere weatherproof, serviceable and safe. An e-house (also called a power distribution center or modular substation) provides that home. Rather than building a concrete substation on site, the switchgear, transformers, protection and controls are integrated and wired inside a steel enclosure at the factory, then delivered pre-commissioned.

The result is fewer trades on site, less weather risk during construction, and a documented factory acceptance test before anything ships. For developers working to tight interconnection deadlines, that predictability is often worth more than the equipment itself.

How to choose

Voltage & power rating

Match the MV switchgear rating and transformer capacity to your point of interconnection and block size.

Footprint & transport

Confirm module dimensions and weight against site access and shipping limits — road, rail and crane.

Climate & enclosure rating

Specify ambient temperature range, IP/NEMA rating and HVAC capacity for the site's climate.

Integration level

Decide how much is pre-integrated — switchgear only, or a complete MV station with transformer and controls.

Standards & testing

Require factory acceptance testing (FAT) and compliance with the relevant IEC / IEEE standards and local grid code.

Serviceability

Check internal clearances, walk-in access and maintainability of the switchgear and protection over the plant's life.

Suppliers & solutions
ABB Switzerland
E-House and Power Distribution Centers

ABB's e-houses are prefabricated, factory-assembled and tested electrical buildings that integrate medium- and low-voltage switchgear, transformers, protection and control, and auxiliary systems into a single transportable module, delivered pre-commissioned to reduce on-site electrical work and shorten project schedules.

Frequently asked questions

What is an e-house in a BESS project?
An e-house — also called a power distribution center or modular substation — is a prefabricated electrical building assembled and tested in a factory, then shipped to site as a complete unit. It houses the medium- and low-voltage equipment that links the batteries to the grid.
What is inside a BESS e-house?
Typically medium-voltage switchgear, step-up and auxiliary transformers, low-voltage distribution, protection, control and metering, and auxiliary systems such as HVAC, lighting and fire detection. The exact contents depend on how much of the medium-voltage station is pre-integrated.
When do I need an e-house instead of a site-built substation?
E-houses suit projects with tight schedules, limited site access or harsh climates, where factory assembly and testing cut on-site work and weather risk. A conventional site-built substation can still make sense for very large or highly customized installations.
How is an e-house different from a skid or MV station?
The terms overlap. A skid is usually an open, frame-mounted assembly, while an e-house is a walk-in weatherproof building. Both integrate the medium- and low-voltage equipment for a BESS — the choice comes down to climate, footprint and how much walk-in serviceability you need.

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