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Guide to TWAICE KPIs

Discover all TWAICE-calculated KPIs

Olivia Willson avatar
Written by Olivia Willson
Updated over 4 months ago

The table below describes all the available, TWAICE-calculated KPIs which can be accessed through the TWAICE Energy Analytics platform, including delivered in which platform feature (e.g. Reports, Performance Manager) and required sensors to calculate that KPI.

All of these KPIs are based on raw data coming from the BESS and leverage TWAICE raw data pre-processing and KPI-specific algorithms and models developed by TWAICE internally.

These KPIs are by standard daily aggregations. Daily KPIs are defines as: daily from 00:00:00UTC until 23:59:59.99UTC

Summary Outlook:

Detailed List:

KPI Name / Unit

Level

Description

Platform Feature

Required Input Sensor

SoH - ref. Installed DC Energy

SoH [%]

Operational data needed

(1-30 cycles)

System & String

State of Health using installed DC Energy as a reference. Installed DC Energy is using a bottom up approach from the cell up to define the total installed energy.

On system level, aggregated state of health across all strings, calculated from individual string SoH values

  • Warranty

  • Reports

  • Performance - Recoverable Energy

  • Health

  • Data Explorer

  • String Current

  • String Voltage

  • String Temperature

SoH - ref. Equipment DC Energy

SoH [%]

Operational data needed (1-30 cycles)

System & String

State of Health using Equipment DC Energy as a reference. Equipment DC Energy is defined during the TWAICE onboarding process for the system. For the string level, the system Equipment DC Energy is divided by the number of strings.

On system level, aggregated state of health across all strings, calculated from individual string SoH values

  • Warranty

  • Data Explorer

  • Reports

  • String Current

  • String Voltage

  • String Temperature

SoH - Energy-based

SoH [MWh / kWh]

Operational data needed (1-30 cycles)

System & String

State of Health focusing on the still usable energy and displaying the amount of energy directly.

On system level, aggregated state of health across all strings, calculated from individual string SoH values

  • Health

  • Warranty

  • Reports

  • String Current

  • String Voltage

  • String Temperature

String DC Resistance

Resistance [Ω]

Operational data needed (1-30 cycles)

String

DC resistance of a full string, which may be influenced by cable connections or faults in components like cells.

  • Health

  • Safety

  • Data Explorer

  • Reports

  • String Current

  • String Voltage

  • String Temperature

String DC Resistance Confidence Interval Upper Bound

Resistance [Ω]

Operational data needed (1-30 cycles)

String

Upper bound of the confidence interval for string DC resistance.

  • Health

  • Data Explorer

  • String Current

  • String Voltage

  • String Temperature

String DC Resistance Confidence Interval Lower Bound

Resistance [Ω]

Operational data needed (1-30 cycles)

String

Lower bound of the confidence interval for string DC resistance.

  • Health

  • Data Explorer

  • String Current

  • String Voltage

  • String Temperature

String SoC

SoC [%]

Operational data needed (1-30 cycles)

String

State of charge of an individual string, calculated using voltage, current, and temperature inputs and based on the TWAICE SoC model.

  • Performance - Imbalance

  • Health

  • Data Explorer

  • Reports

  • String Current

  • String Voltage

  • String Temperature

String Cell SoC Max

SoC [%]

Operational data needed (1-30 cycles)

String

Maximum SoC in a string, derived from the maximum cell voltage within the string and based on the TWAICE SoC model.

  • Performance - Imbalance

  • Data Explorer

  • String Current

  • String Max Cell Voltage

  • String Temperature

String Cell SoC Min

SoC [%]

Operational data needed (1-30 cycles)

String

Minimum SoC in a string, derived from the minimum cell voltage within the string and based on the TWAICE SoC model.

  • Performance - Imbalance

  • Data Explorer

  • String Current

  • String Min Cell Voltage

  • String Temperature

String Cell SoC Spread

SoC [%]

Available when data connection established

String

Difference between max and min SoC in a string, indicating internal imbalances.

  • Performance - Imbalance

  • Data Explorer

  • Reports

  • String Current

  • String Max Cell Voltage

  • String Min Cell Voltage

  • String Temperature

String Self-Discharge

Voltage [V]

Available when data connection established

String

Classification if the min cell voltage of a cell within a string is drifting away

  • Safety

  • String Min Cell Voltage

String Energy Throughput charge (daily/ cumulative)

Energy [Wh]

Available when data connection established

String

Total charged energy throughput per string, tracked daily and cumulatively.

  • Data Explorer

  • Reports

  • String Current

  • String Voltage

String Energy Throughput discharge (daily/ cumulative)

Energy [Wh]

Available when data connection established

String

Total discharged energy throughput per string, tracked daily and cumulatively.

  • Data Explorer

  • Reports

  • String Current

  • String Voltage

String Energy Throughput net (daily/ cumulative)

Energy [Wh]

Available when data connection established

String

Net energy throughput (charge minus discharge) of a string, tracked daily and cumulatively.

  • Data Explorer

  • String Current

  • String Voltage

String Energy Throughput absolute (daily/ cumulative)

Energy [Wh]

Available when data connection established

String

Absolute energy throughput of a string, summing all energy flows regardless of direction.

  • Data Explorer

  • Reports

  • String Current

  • String Voltage

String Capacity Throughput charge (daily/ cumulative)

Charge [Ah]

Available when data connection established

String

Total charged capacity throughput in Ah for a string, tracked daily and cumulatively.

  • Data Explorer

  • String Current

String Capacity Throughput discharge (daily/ cumulative)

Charge [Ah]

Available when data connection established

String

Total discharged capacity throughput in Ah for a string, tracked daily and cumulatively.

  • Data Explorer

  • String Current

String Capacity Throughput net (daily/ cumulative)

Charge [Ah]

Available when data connection established

String

Net capacity throughput in Ah for a string (charge minus discharge), tracked daily and cumulatively.

  • Data Explorer

  • String Current

String Capacity Throughput absolute (daily/ cumulative)

Charge [Ah]

Available when data connection established

String

Sum of all charge and discharge capacity throughputs for a string in Ah, tracked daily and cumulatively.

  • Data Explorer

  • String Current

String Equivalent Full Cycles (daily/ cumulative)

Counter [-]

Available when data connection established

String

Number of full equivalent charge/discharge cycles per string (0% to 100% and back), tracked daily and cumulatively.

  • Health

  • Warranty

  • Data Explorer

  • String Current

String Equivalent Full Charge Cycles (daily/ cumulative)

Counter [-]

Available when data connection established

String

Full charge cycles per string, calculated from 0% to 100% SoC transitions, tracked daily and cumulatively.

  • Data Explorer

  • String Current

String Equivalent Full Discharge Cycles (daily/ cumulative)

Counter [-]

Available when data connection established

String

Full discharge cycles per string, calculated from 100% to 0% SoC transitions, tracked daily and cumulatively.

  • Data Explorer

  • String Current

String Equivalent Energy Cycles (daily/ cumulative)

Counter [-]

Available when data connection established

String

Equivalent full energy cycles based on energy throughput (Wh) from 0% to 100% SoC and back, tracked daily and cumulatively.

  • Data Explorer

  • String Current

  • String Voltage

String Equivalent Energy Charge Cycles (daily/ cumulative)

Counter [-]

Available when data connection established

String

Equivalent full charge energy cycles, based on energy throughput (Wh) from 0% to 100% SoC, tracked daily and cumulatively.

  • Data Explorer

  • String Current

  • String Voltage

String Equivalent Energy Discharge Cycles (daily/ cumulative)

Counter [-]

Available when data connection established

String

Equivalent full discharge energy cycles, based on energy throughput (Wh) from 100% to 0% SoC, tracked daily and cumulatively.

  • Data Explorer

  • String Current

  • String Voltage

String Cell Voltage Spread

Voltage [V]

Available when data connection established

String

Voltage difference between the highest and lowest cell voltage in a string, showing internal string imbalance.

  • Performance - Imbalance

  • Health

  • System Monitor

  • Data Explorer

  • String Max Cell Voltage

  • String Min Cell Voltage

String Module Temperature Spread

Temperature [°C]

Available when data connection established

String

Difference between the highest and lowest module temperatures within a string, showing thermal imbalance.

  • Performance - Temperature

  • Health

  • System Monitor

  • Data Explorer

  • Reports

  • String Max Module Temp

  • String Min Module Temp

String Non-operational

Status [-]

Available when data connection established

String

A string is marked non-operational if it sees less than 0.01 equivalent full cycles while peer strings see more than 0.01 on the same day.

  • Performance - Recoverable Energy

  • System Monitor

  • Reports

  • String Current

String RTE

RTE [%]

Available when data connection established

String

Round-trip efficiency of an individual string, calculated from energy throughput.

  • Data Explorer

  • String Current

  • String Min Cell Voltage

  • String Temp

Inverter RTE

RTE [%]

Available when data connection established

Inverter

Round-trip efficiency of the inverter, calculated from inverter-level signals and energy throughput.

  • Data Explorer

  • Inverter Active Power

  • System Active Power

    AND

  • Inverter Current DC

  • Inverter Voltage DC

    OR

  • Inverter Power DC

Transformer RTE

RTE [%]

Available when data connection established

Transformer

Round-trip efficiency of the transformer, based on energy throughput.

  • Data Explorer

  • Inverter Active Power

  • System Active Power

    AND

  • Inverter Current DC

  • Inverter Voltage DC

    OR

  • Inverter Power DC

System RTE

RTE [%]

Available when data connection established

System

System-wide round-trip efficiency, aggregating values from string, inverter, and transformer levels.

  • Warranty

  • Data Explorer

  • Reports

  • String Current

  • String Voltage

  • String Temperature

  • Inverter Active Power

  • System Active Power

    AND

  • Inverter Current DC

  • Inverter Voltage DC

    OR

  • Inverter Power DC

System Availability

Availability [%] and [MWh]

Available when data connection established

System

Reflects daily component availability based on string non-operational KPIs and aggregated to system level.

  • Warranty

  • Data Explorer

  • Reports

  • String Current

Total Usable Energy

Energy [MWh]

Operational data needed (1-30 cycles)

System

Usable energy for daily operation, accounting for aging, recoverable energy, and missing data.

  • Performance - Recoverable Energy

  • Data Explorer

  • Reports

  • String Current

  • String Voltage

  • String Max Cell Voltage

  • String Min Cell Voltage

  • String Min/ Max Cell ID or Location

  • String Temperature

Inverter Usable Energy

Energy [MWh]

Operational data needed (1-30 cycles)

Inverter

Usable energy from one inverter for daily operation, considering aging, recoverable energy, and missing data.

  • Performance - Recoverable Energy

  • String Current

  • String Voltage

  • String Max Cell Voltage

  • String Min Cell Voltage

  • String Min/ Max Cell ID or Location

  • String Temperature

String Usable Energy

Energy [kWh]

Operational data needed (1-30 cycles)

String

Usable energy from a single string for daily operation, taking aging, imbalances, non-operation and weak cells into account.

  • Performance - Recoverable Energy

  • String Current

  • String Voltage

  • String Max Cell Voltage

  • String Min Cell Voltage

  • String Min/ Max Cell ID or Location

  • String Temperature

Total Recoverable Energy

Energy [MWh]

Operational data needed (1-30 cycles)

System

Recoverable energy on system level due to non-operational components, weak cells or imbalances.

  • Performance - Recoverable Energy

  • Reports

  • String Current

  • String Voltage

  • String Max Cell Voltage

  • String Min Cell Voltage

  • String Min/ Max Cell ID or Location

  • String Temperature

Inverter Recoverable Energy

Energy [MWh]

Operational data needed (1-30 cycles)

Inverter

Recoverable energy on inverter level due to non-operational components, weak cells or imbalances.

  • Performance - Recoverable Energy Energy

  • String Current

  • String Voltage

  • String Max Cell Voltage

  • String Min Cell Voltage

  • String Min/ Max Cell ID or Location

  • String Temperature

String Recoverable Energy

Energy [kWh]

Operational data needed (1-30 cycles)

String

Recoverable energy on string level due to non-operation, weak cells or imbalances.

  • Performance - Recoverable Energy

  • String Current

  • String Voltage

  • String Max Cell Voltage

  • String Min Cell Voltage

  • String Min/ Max Cell ID or Location

  • String Temperature

Depth of Discharge (DoD)

Percentage [%]

Available when data connection established

String

The daily maximum difference between the maximum and minimum State of Charge

  • Warranty

  • BMS SoC

  • TWAICE SoC

String Penalty Cycles (daily/ cumulative)

Counter [-]

Available when data connection established

String

Cycle count meeting defined penalty conditions as specified in warranty contract, tracked daily and cumulatively.

  • Warranty

  • Data Explorer

  • String Current

  • Warranty-specific inputs

String Warranty-relevant Cycles (daily/ cumulative)

Counter [-]

Available when data connection established

String

Cycle count including penalty cycles, tracked daily and cumulatively.

  • Warranty

  • Data Explorer

  • String Current

  • Warranty-specific inputs

Weak Cell Detection

Boolean [-]

Operational data needed (1-30 cycles)

String

Identification of individual cells which are limiting the string performance

  • Performance - Recoverable Energy

  • String Max Cell Voltage

  • String Min Cell Voltage

  • String Min/ Max Cell ID or Location

If you have more questions, do not hesitate to reach out!

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