BESS commissioning: tests and requirements

Short answer

Commissioning a battery energy storage system (BESS) proves that the battery banks, their management system, the power conversion system, the transformer, the switchgear, the protection, the safety systems and the controls work as a whole and meet the requirements of the grid interconnection. It combines the battery manufacturer's tests with substation electrical tests and performance tests of the complete system.

What a BESS is and what gets commissioned

A battery energy storage system (BESS) is much more than a container of batteries. In a grid-connected installation you find:

Battery banks in racks, with their battery management system (BMS), which supervises the voltages, temperatures and state of charge of every module.
Power conversion system (PCS), which converts the DC from the batteries to AC and controls active and reactive power.
Step-up transformer and medium-voltage switchgear, sometimes a complete substation.
Protection at the point of interconnection and for each piece of equipment.
Safety systems: fire detection and suppression, gas detection, ventilation and HVAC.
Energy management system (EMS) and plant controller, integrated with SCADA and the control center.

Commissioning proves, with the same stages as substation commissioning, that all of this works as a whole, safely, and that the system delivers what the grid interconnection requires.

Reference standards

IEC 62933 series, from technical committee IEC TC 120, for electrical energy storage systems. IEC 62933-2-1 covers unit parameters and their test methods, and IEC 62933-5-2 the safety of grid-integrated systems using electrochemical storage, over their whole life cycle and considering the interactions between subsystems.
NFPA 855, the installation standard for stationary energy storage systems, adopted by many US jurisdictions and often included in project specifications elsewhere. Among other topics, it covers commissioning and decommissioning. UL 9540 (system safety) and UL 9540A (thermal runaway fire propagation test method) usually go with it.
Product standards for the batteries, the PCS, the transformer and the switchgear.
Utility interconnection requirements: the grid code and the tests of the utility or system operator, which may reference IEEE 1547 or IEEE 2800 depending on the connection point.

Editions change often: the test plan should cite the edition agreed in the contract.

Commissioning stages

BESS commissioning

01Inspection and pre-commissioningInstallation, grounding, DC and AC wiring, safety systems
02Equipment testsTransformer, switchgear, cables, protection and PCS without the grid
03Battery and BMS energizationStart-up per the manufacturer, module supervision
04Energization from the gridTransformer, PCS and synchronization
05Performance testsCharge, discharge, response and power control
06Interconnection testsThose the utility requires for commercial operation

Inspection and pre-commissioning

Installation of racks and containers, grounding, DC and AC wiring, labeling and, above all, the safety systems: fire detection and suppression, ventilation, HVAC and emergency stops must be tested before the batteries are energized. The split between what is tested de-energized and energized is explained in cold and hot commissioning.

Substation electrical tests

The AC side is commissioned like any substation: primary equipment tests on the transformer, switchgear and cables, and protection tests with secondary injection and the approved settings. The first energization from the grid follows the sequence of first energization of a new substation.

Batteries, BMS and PCS

Energizing the banks and starting up the BMS and the PCS follow the manufacturer’s procedure, which usually requires their presence or authorization to keep the warranty. On the electrical side, the consistency of measurements between the BMS, the PCS and the meters, the trips on abnormal conditions and the communications between the three control levels are verified.

Performance tests

With the system connected, charge and discharge cycles, available power and energy, round-trip efficiency, response to active and reactive power setpoints and the operating modes defined in the contract are tested. IEC 62933-2-1 describes methods for parameters of this kind. These tests set the baseline of the system: the capacity measured at commissioning is the reference against which battery degradation will be assessed over its life, and it is usually tied to the supplier’s warranty.

Integration and utility requirements

The EMS and the plant controller are integrated with SCADA and the control center through their signal list; the logic is similar to that of a solar power plant controller. Finally, the interconnection tests required by the utility are carried out. Their scope depends on the grid code and the interconnection agreement, so it should be confirmed with the utility before planning the tests.

Risks specific to a BESS

Stored energy. Unlike a substation, a battery bank is not “de-energized” by opening a breaker: the DC terminals stay live. This changes the work procedures.
Thermal runaway. An internal fault in a cell can propagate; that is why the safety systems are tested first.
Control interaction. The BMS, PCS, EMS and plant controller must respond consistently; a configuration error can cause trips or limit power without a real fault.
Protection at the point of interconnection. A BESS can import and export power: directionality and reverse power protection must be set for both directions.

The detailed energization procedure for the batteries and the PCS belongs to the manufacturer; the system test plan is defined with the project specification.

BESS commissioning with Tiza Group

Our crew commissions the electrical side of grid-connected storage systems: substation, switchgear, transformer, protection at the point of interconnection, controls and SCADA integration, in Colombia, or elsewhere on request. Contact us about your project.

References

IEC 62933-2-1, Electrical energy storage (EES) systems – Part 2-1: Unit parameters and testing methods – General specification.
IEC 62933-5-2, Electrical energy storage (EES) systems – Part 5-2: Safety requirements for grid-integrated EES systems – Electrochemical-based systems.
NFPA 855, Standard for the Installation of Stationary Energy Storage Systems.
UL 9540, Energy Storage Systems and Equipment; UL 9540A, Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems.
IEEE C37.233-2023, IEEE Guide for Power System Protection Testing.

Frequently asked questions

What is tested when commissioning a BESS?

The battery banks and their battery management system (BMS), the power conversion system (PCS), the transformer and medium-voltage switchgear, the protection at the point of interconnection, the safety systems (fire detection and suppression, ventilation and HVAC), the energy management system (EMS) and the SCADA integration. Finally, the performance of the complete system is tested while charging and discharging.

Which standard applies to BESS commissioning?

There is no single one. The IEC 62933 series covers grid-integrated storage systems, with performance and safety parts; NFPA 855 covers safe installation in the jurisdictions that adopt it; UL 9540 and UL 9540A are common in North American specifications; and each utility sets its own interconnection tests. The batteries and the PCS also come with their own product standards.

Who defines the tests a BESS must pass before commercial operation?

The utility or system operator the plant connects to, through its interconnection requirements and grid code, together with the contract. Depending on the connection point, references such as IEEE 1547 or IEEE 2800 may apply. The specific tests should be confirmed with the utility early in the project.