“Rakit” Multi-functional High-speed I-V Measurement System | NPC incorporated

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“Rakit” Multi-functional High-speed I-V Measurement System

PV Panel Inspection Machine


Rakit is a maintenance device to measure current and voltage characteristics string by string, to grasp PV system characteristics, abnormal data, etc.
The device comprising of I-V tracer, pyranometer, thermocouple, data logger, and "I-V data analyzer," the multi-functional analyzing software, provides accurate analysis report quickly. The I-V data analyzer is compatible with the following I-V tracers:

  • Togami Electric Mfg.: SPST-A1
  • EKO Instruments: MP-11
  • Nippon Kernel System: Epsilon1000



4 min. 20 sec. subtitle: Japanese

Features of Rakit

Reduced power generation loss by quick measurement; faults detectable at a glance

Rakit measures up to 4 strings *1 at a time thanks to multiple probes (patented on multi-probe holder: JP5912156) of I-V tracer. Measurement time is shortened up to 2 hours per MW *2, thus power generation loss is reduced. Also, strings with defects can be detected immediately by comparing open voltage values.

Simultaneously measures up to 4 strings

*1 When string tracer made by Togami is used.
*2 Time required changes depending on actual installation conditions, environment, etc.

Adjustment according to irradiance and temperature (STC conversion) provides accurate data

Weather continuously changes during maintenance operation. Rakit provides accurate analysis results by automatically converting the measured data to values under standard test conditions (STC)*3 according to the irradiance and temperature stored in the data logger.


*3 Temperature: 25 degrees Celsius, irradiance: 1,000W/m²

I-V Data Analyzer: easy-to-use software enabling analysis anywhere

rakit img03

All you need is an internet environment: you can use the software anywhere. The cloud server enables remote data sharing among operators*4. User-friendly interface provides comfortable operation.

Only internet environment is required

Only internet environment
is required

Data sharing among operators

Data sharing among operators

Simple interface

Simple interface

*4 One login per ID is allowed at a time.

Analysis report automatically issued in as little as 3 minutes

NPC original algorithm is used for analysis. From calculation, analysis to report issuance will be finished in only 3 minutes per MW. *5
3 decision criteria of resistance, I-V, and electricity are available for detecting abnormal values of strings. Abnormal Isc and Voc can be detected by comparing data simultaneously measured.

CriteriaAbnormal pointsPossible causes
FF comparisonIncrease/Decrease in serial/parallel resistanceWiring peel-off, crack, PID*6, etc
Comparison of values measured simultaneouslyDecrease in Voc/IscDiode shortage, disconnection, discoloration of encapsulant, etc.
Pmax comparisonDecrease in PmaxAll above
FF comparison
Increase/Decrease in serial/parallel resistance
Wiring peel-off, crack, PID*6, etc
Abnormal points
Comparison of values measured simultaneously
Decrease in Voc/Isc
Diode shortage, disconnection, discoloration of encapsulant, etc.
Possible causes
Pmax comparison
Decrease in Pmax
All above

Examples of Analysis Screen

Pmax histogram after STC conversion
(Shows total power output, power output difference of each string, etc.)
FF histogram
(Shows power generation tendency. Criteria of strings changeable.)

I-V curves of all strings to be inspected and of good string
(Shows abnormality by comparison)

Respective I-V curve of string to be inspected
(Shows I-V curves of abnormal strings one by one)

*5 Time required changes depending on actual installation conditions, environment, etc.

*6 Degradation phenomena often seen when plenty of series-connected PV panels are operated under high voltage.

Panel maintenance consulting services

Contact us for technical questions regarding
effective data recording, how to use Rakit, measured data, etc.

+81-89-946-6605( Matsuyama Factory)

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