Skip to main content
Once planning is complete and EPC providers are on board, the project moves into Construction & Commissioning — where the blueprints become a reality, culminating in the asset’s official go-live moment: Commercial Operation Date (COD).

​
Construction: Building the Facility

This stage involves the physical development of the site, transforming a plot of land into a complex energy facility:
  • Site preparation: Clearing and levelling the land, creating foundations, and installing initial infrastructure like drainage and access roads.
  • Component installation: Positioning the battery containers, installing inverters and transformers, setting up switchgear and internal electrical systems, and assembling enclosures with their critical fire suppression, HVAC, and noise suppression systems.
  • Grid connection: Physically connecting the BESS to the designated connection point on the TSO’s or DSO’s network.
Safety protocols are extremely strict throughout construction, ensuring the well-being of all workers on site.

​
Commissioning: Testing Before Commercial Operation

Once construction is largely complete, the BESS undergoes rigorous commissioning — a methodical process of testing all systems to ensure they work correctly, safely, and meet all technical and regulatory standards. Several layers of testing are involved:
  • Individual component tests: Each piece of equipment (an inverter, a battery module, a sensor) is tested in isolation to confirm it functions to manufacturer specifications.
  • Subsystem integration tests: Verifying how different components work together — the BMS communicating with the EMS, the EMS controlling the inverters, fire suppression sensors communicating with the Site Controller.
  • Full system performance tests: The entire BESS is operated at various power levels and modes to confirm overall performance, stability, and safety under different conditions, including simulated fault scenarios.
  • Communication pathway tests: Verifying that all external communication interfaces (the IoT Box, Ancillary Services Pool Box, and EZA Regler) reliably exchange data and commands with external parties.

​
Regulatory Compliance: VDE-AR-N Standards

A critical part of commissioning in Germany involves adhering to the VDE-AR-N standards. These standards (VDE-AR-N 4105 for low voltage, VDE-AR-N 4110 for medium voltage, VDE-AR-N 4120 for high voltage) define stringent requirements for how power generation or storage plants must behave when connected to the grid. The BESS must demonstrate compliance by passing tests that verify its ability to:
  • Operate within specified voltage and frequency ranges.
  • Provide reactive power support to help stabilise grid voltage.
  • Maintain operation during certain grid disturbances (fault ride-through capability).
  • Communicate reliably with grid operators.
Passing these tests and receiving the required VDE certification is essential for legal operation and for reaching COD.

​
Commercial Operation Date (COD): The Go-Live Moment

COD is the official date when the BESS is deemed fully built, rigorously tested, compliant with all relevant technical and regulatory standards, and ready to begin its commercial life — generating revenue by participating in electricity markets.
COD is a crucial milestone for investors. It marks the point when the asset transitions from being a capital expenditure to a revenue-generating entity. Many financial agreements and contracts become fully active from this date.
At COD, the asset can participate in wholesale market trading. However, participation in ancillary services markets requires an additional certification step — Ancillary Services Prequalification — which must be completed after COD.
Last modified on April 20, 2026