Poland C&I High Voltage ESS Case Study: 2×100kWh ESS Battery Storage in Parallel

Project Year: 2026
Location: Poland
System Topology: 2 × 100kWh ESS battery cabinets in parallel
Cooling Method: Air-cooled integrated cabinet
Inverter: Deye (external connection)
Application: Commercial & Industrial peak shaving + backup power

Project Background

In 2026, multiple C&I energy storage projects were commissioned across Poland to address rising electricity tariffs, grid instability, and demand charge pressure for commercial facilities. Among them, this site deployed two 100kWh high voltage ESS battery storage cabinets in parallel, forming a modular 200kWh C&I energy storage system.

The client required:

Peak shaving during daytime production hours

Backup power during grid interruptions

Stable integration with existing PV and AC distribution

A solution that is simple to install, easy to scale, and operationally reliable

System Architecture

This solution adopts an air-cooled all-in-one ESS cabinet paired with external Deye inverters. The batteries operate on a high voltage DC bus, improving efficiency and reducing current losses compared with low-voltage systems.

Architecture Highlights

High voltage ESS battery clusters are inside each cabinet

Independent BMS per cabinet, coordinated in parallel

External inverter coupling for flexible AC integration

Standard air-cooling with intelligent thermal management

Plug-and-play parallel expansion

Why Air-Cooled ESS for This Site?

For medium-scale C&I projects (100–300kWh), air-cooled ESS battery storage provides a cost-effective and highly reliable solution without the complexity of liquid cooling.

Advantages realized on site:

Installation & Commissioning

The two ESS battery cabinets were installed side-by-side and connected in parallel on the DC side, then interfaced with the Deye inverter on the AC side.

Commissioning steps included:

Parallel communication setup between BMS units

High voltage DC bus configuration

Inverter parameter matching for ESS operation mode

Charge/discharge scheduling for peak shaving

Backup mode verification during simulated grid outage

The entire system was brought online smoothly with minimal integration effort.

Operational Results & Client Feedback

After several months of operation, the client reported:

Stable daily peak shaving performance

Noticeable reduction in electricity bills

Seamless transition during grid power loss

Consistent thermal performance from the air-cooled design

Highly stable cooperation with Deye inverter

“The system runs very stably. Installation was straightforward, and performance has met our expectations for both cost savings and backup reliability.”

Technical Snapshot

Why This High Voltage ESS Design Works for C&I

This Poland project demonstrates a repeatable model for medium-scale commercial energy storage:

Avoid over-engineering with liquid cooling where unnecessary

Use modular ESS battery cabinets for scalability

Keep the inverter external for integration flexibility

Leverage high voltage ESS for efficiency and performance

It provides an optimal balance between CAPEX, operational reliability, and future expansion capability—a reference design for similar C&I scenarios across Europe.