1. Rakit

Products and Services
Photovoltaic Systems Related Products

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

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/A2
  • EKO Instruments: MP-11
  • Nippon Kernel System: Epsilon1000

See Rakit video and how I-V characteristics are measured at an actual plant.
Rakit video on YouTube(4 min. 20 sec. subtitle: Japanese)

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.

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.

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

  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.
cloud server   data sharing   interface
Only internet environment
is required
  Data sharing among operators   Simple interface

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. *2
  • 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.

Criteria Abnormal points Possible causes
FF comparison Increase/Decrease in serial/parallel resistance Wiring peel-off, crack, PID*5, etc.
Comparison of values measured simultaneously Decrease in Voc/Isc Diode shortage, disconnection, discoloration of encapsulant, etc.
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)

Panel maintenance consulting services

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

E-mail: pv.mente@npcgroup.net

  • *1 When string tracer made by Togami is used.
  • *2 Time required changes depending on actual installation conditions, environment, etc.
  • *3 Temperature: 25 degrees Celsius, irradiance: 1,000W/m²
  • *4 One login per ID is allowed at a time.
  • *5 Degradation phenomena often seen when plenty of series-connected PV panels are operated under high voltage.


Environmental Products Sales Department
Matsuyama Factory, Japan Tel: +81 89 946 6605
Tokyo Headquarters, Japan Tel: +81 3 5817 8830