BESS performance data

BESS performance data states the capacity, power, round trip efficiency, and durability of a stationary system under stated conditions, for the configuration as installed and as tested. Performance values for stationary batteries are set in the context of Articles 9 and 10 and Annexes IV and V, where those provisions apply to the battery category, and in the performance test methods in related IEC standards, including IEC 62620 for stationary applications. A nameplate capacity without a test method, a temperature, a rate, and a depth of discharge cannot be compared with a site measurement, and a factory acceptance test result cannot be presented as a site acceptance result. The record must hold both results separately, with dates, conditions, and testers, so the system can be judged at handover and over its life.

BESS performance data means the measured capacity, power, efficiency, and durability values for a stationary battery system. The scope is the system and configuration stated, for the test or operating period stated.

How is the stationary category decided?

BESS performance data applies within that frame, and the record should not borrow an EV battery rule without checking whether the article applies to industrial batteries. Articles 9 and 10 is the operative provision for the point in question. A commissioning engineer recording factory and site acceptance tests for a storage container should record the category decision, including the capacity calculation and the date, because the threshold decision decides whether a passport is required. A container should show a factory capacity test at stated conditions, a site capacity test after installation, and a round trip efficiency measurement over a stated cycle, each with conditions and dates, rather than a single capacity figure.

How is the record built in layers?

For BESS performance data, each layer should name its source, its date, and its owner. Factory and site test reports, method notes, and performance entries should be tied to the identifier, so a maintenance entry, a commissioning test, and a passport entry refer to the same system. Degradation over calendar time and cycle count should be tracked separately, since a system that cycles rarely can still lose capacity with age, and a record that tracks only cycles will miss calendar ageing.

How is performance measured in service?

For BESS performance data, the record should state the capacity test method, the temperature range, the charge and discharge rates, the depth of discharge, and the end of life criterion used for a durability statement. A commissioning engineer recording factory and site acceptance tests for a storage container should name the standard or method used for each value and should not present a laboratory value as a site value without stating the difference. A container should show a factory capacity test at stated conditions, a site capacity test after installation, and a round trip efficiency measurement over a stated cycle, each with conditions and dates, rather than a single capacity figure.

How is safety information recorded?

For BESS performance data, the record should state the safety tests applied, the battery management system functions that protect the system, the ventilation or enclosure requirements, and the instructions given to the site operator. Factory and site test reports, method notes, and performance entries should include the test reports, the installation instructions, and the handover of safety information, each dated. Degradation over calendar time and cycle count should be tracked separately, since a system that cycles rarely can still lose capacity with age, and a record that tracks only cycles will miss calendar ageing.

How are installation and maintenance recorded?

For BESS performance data, the commissioning record should state the installer, the date, the tests passed, the settings applied, and any deviations from the design. A commissioning engineer recording factory and site acceptance tests for a storage container should ensure that maintenance entries update the passport or the linked record where the Regulation requires an update, and that earlier entries are preserved. A container should show a factory capacity test at stated conditions, a site capacity test after installation, and a round trip efficiency measurement over a stated cycle, each with conditions and dates, rather than a single capacity figure.

How are transfer and end of life decisions recorded?

For BESS performance data, a transfer of ownership, a change of application, a repurposing of EV modules into stationary service, or a move to recycling each needs a dated entry, a named operator, and a statement of what was transferred. Factory and site test reports, method notes, and performance entries should include the state of health assessment, the safety checks applied, and the new application, where a second life use is claimed. Degradation over calendar time and cycle count should be tracked separately, since a system that cycles rarely can still lose capacity with age, and a record that tracks only cycles will miss calendar ageing. A commissioning engineer recording factory and site acceptance tests for a storage container should check the passport or linked record at transfer, record any gap found, and give the gap an owner and a review date.

How is a performance trend built over two years?

A trend over two years is built from periodic measurements under the same method: capacity tests at stated intervals, round trip efficiency measurements over stated cycles, and cycle counts, each dated. A worked trend table shows six capacity measurements over two years, each with the method, the temperature, and the rate, plus the cycle count at each date. The trend is drawn only from measurements under the same method, and a method change starts a new trend with a note. Calendar ageing is shown alongside cycle count, so a system with few cycles but a falling capacity trend is not misread as a cycling failure. The trend is filed with the performance entries, so a later assessment can see the whole history, not only the latest figure.

Performance is a series of dated measurements, and a single early measurement does not describe a system that has been operating for years.