Certification

Grid-connected Inverters (Power conditioners) for small distributed generation systems

JET’s certification system is the system to carry out product testing to ensure conformity to JET’s certification testing standard prepared based on the Grid-interconnection Technical Requirement Guidelines (currently the Grid-interconnection Technical Requirement Guidelines on Quality of Electricity and the Official Interpretation of Technical Requirement of Electric Facilities under the Electricity Utilities Industry Law) and the Electrical Appliance and Material Safety Law etc., and also carry out a factory inspection to ensure that continued production of the products equivalent to this model is possible and then, issue the certification to the approved products.

Purpose of certification

For the main purpose of insuring safety in small distributed generation systems for household use as well as smoothing grid-interconnection procedure, JET accepts applications from manufacturers, distributors, and importers of grid-connected inverters (power conditioners) of small distributed generation systems (hereafter referred to as “grid-connected equipment”), and issues certification after carrying out certification testing and factory inspection.

Area of application

Products eligible for certification include the following grid-interconnection equipment, etc, utilizing inverter, etc.

  • Products for use in photovoltaic power generation system, gas engine cogeneration units, or stationary compact fuel cell power generation systems.
  • Products conform to requirements for grid-interconnection to power distribution lines.
  • Photovoltaic (PV) power generation systems : less than 20kW output
  • Gas engine cogeneration units : less than 10kW output
  • Products for stationary compact fuel cell power generation systems: less than 10kW output
  • Products for multiple grid-interconnection for PV power generation systems: less than 6kW output.

The process flow up to certification registration

The process for certification is displayed in Diagram 1

flow

The process for certification is displayed in Diagram 1

  • Certification Application
    Application for certification requires that the applicant submit the identification number (model number) of grid-connected equipment, in the same condition as one that can be sold as a certified product.
  • Certification Testing
    Certification testing verifies that grid-connected equipment , has protective functions, performance, and safety conforming to the certification testing standard.
  • Factory Inspection
    A factory inspection is carried out initially and on a general yearly basis in order to verify that quality control standards allow continued production of a product conforming to the certification testing standard.
  • Certification Registration
    Products conforming to the certification testing and factory inspection will undergo certification registration, and be publicly notified (currently on the JET homepage).
  • Certification Period of Validity
    Certification is valid for five years. However, in the event of a revision to the Grid-interconnection Code (JEAC 9701, JEA), etc., the period of validity may be shortened with advance notification if necessary.
  • Certification Label
    Until the certified products are shipped from the manufacturing factory, the certification label below should be applied to certified products in an easily visible location.
Certification Label

Details of certification testing

Testing method related to the certification process for grid-inter connection involves general rules of testing methods compiling common items of each system as well as the testing methods describing individual testing items of each system. The certification testing process is carried out based on the combination of the above, the general rules and the individual methods appropriate to the particular power generation system.

  • General Rules for Test Method of Grid-connected Protective Equipment etc. for Small Distributed Generation Systems
  • Individual Test Method of Grid-connected Protective Equipment etc. for Grid-connected PV Power Generating Systems (for PV Power Generating Systems)
  • Individual Test Method of Grid-connected Protective Equipment etc. for Grid-connected Gas Engine Cogeneration Systems (for Gas Engine Cogeneration Systems)
  • Individual Test Method of Grid-connected Protective Equipment etc. for Grid-connected Stationary FuelCell Power Generation Systems (for Stationary Fuel Cell Power Generation Systems)
  • Individual Test Method of Grid-connected Protective Equipment etc. for Multi-unit Grid-connected PV Power Generating Systems (for PV Multi-unit Grid-interconnection Systems)

The certification testing consists of functionality verification of various protective functions of grid-connected inverter such as automatic separation of power generation system from the grid system at the time of distribution line problem, power outage, power generation system problem etc. as well as performance testing for stability and environmental resistance against change in the inverter’s direct current input, change in load, or other disturbance incoming from the power supply system etc. Tests can be classified in the 12 types below, with a total of 50 test details.

  • Construction test
  • Insulation performance (insulation resistance, power frequency withstand voltage, lightning impulse withstand voltage)
  • Protective functions(simulated input tests: AC over-current, DC overvoltage and under-voltage, DC-component detection, actual operation tests: AC overvoltage and under-voltage, frequency rise and drop, reverse power flow prevention, reverse charging prevention, frequency feedback function, step injection function, islanding prevention 1, islanding prevention 2, fixed time closing block after reenergizing, instantaneous (unbalanced) overvoltage.
    The protection level and operating time of protective functions necessary to grid connection (voltage, frequency abnormalities, islanding protection functions, etc) shall be within specifications.
  • Steady-state characteristics(AC voltage following, frequency following, operation power factor, output harmonic current, leakage current, suppression function for voltage rise, temperature rise, soft start functions)
    Basic features such as the inverter’s output power factor to the distribution line and current distortion levels shall be within specifications.
  • Transient response characteristics (sudden input power change, sudden grid voltage change, sudden grid voltage phase change (10 degrees), sudden grid voltage phase change (120 degrees), sudden grid voltage imbalance.)
    Functionality of the inverter’s output in the event of sudden changes in solar radiation or distribution line voltage shall be stable.
  • External faults (AC short circuit, instantaneous voltage drop, load interruption)
    Functionality of the inverter’s output in the event of an instantaneous voltage drop shall be stable.
  • Electromagnetic emission(radiated disturbance, conducted disturbance)
    The inverter shall not create adverse effects such as radio noise, conducted disturbance etc. to outside
  • Electric Environment Resistance(grid voltage distortion resistance, grid voltage imbalance, surge immunity, imbalance, 5 other items)
    The inverter shall not have reactive malfunctions as a result of distribution line voltage distortions, surge voltage, or other external noises.
  • Ambient environment resistance(humidity, humidity-freeze cycle, wet)
    The insulation performance of the inverter in its stationed environment (humidity conditions) shall be maintained.
  • Durability
    The performance of switches and other parts with mechanical movement shall be ensured.
  • Parts failure
  • Isolated operation

* Based on the specifications and generation systems of the product, some tests may not be carried out.

Information about each test is available in a PDF file which we can send via e-mail. For those who wish to view the information, please make a request by filling out the required fields of the form below.

Contact the following for further information

Power Technology Testing Laboratory
TEL:+81-45-570-2075 FAX:+81-45-570-2077 E-mail:jet-grid@jet.or.jp

Last Update:2016.04.01