Maintenance of solar PV systems according to the IEC 62446-1 Standard

Proper maintenance is necessary for the safe and reliable functioning of long-term solar power generation systems for decarbonization. So conducting electrical testing on the system according to the international standard is important. This article discusses the DC side testing of the IEC 62446-1 standard.

About IEC 62446-1

The IEC 62446-1 is an international standard for testing, documenting, and maintaining grid-connected photovoltaic systems. It sets standards for how system designers and installers of grid-connected PV systems must provide information and documentation to customers. This standard also describes DC testing of the PV system, which can also be used for periodic testing of the system.

In the standard, the test is classified into categories 1 and 2 according to the size of the PV system. Category 1 applies to all solar PV generation systems. Category 2 applies for larger or more complex systems such as mega solar power plant.

  • Small-scale PV power generation system
  • Mega-solar power plant

Category 1 Inspection

Inspection itemsDescriptionMeasuring Instruments
Earth protective continuity test and/or equipotential bonding conductorIf the DC side has earthing, such as a frame or equipotential bonding, a continuity test is required.
  • *Ω function
Polarity inspectionCheck the polarity of the cables before connecting them to the switching device or inverter.
Combiner box testA test to verify that all strings are connected correctly.
Strings open circuit voltage testOpen new windowFor checking the voltage of PV modules connected in series.
String circuit current test (short circuit or operational)Open new windowTo confirm the function of strings and that there are no major issues
Functional testCheck the operation and installation of control devices such as relay switches and circuit breakers.
Insulation resistance testOpen new windowTest the insulation resistance to ensure electrical safety.

All Category 1 tests must be completed and passed before moving on to the additional Category 2 tests.

  • Strings open circuit voltage test and string current test
  • Insulation resistance test

Category 2 Inspection

Inspection itemsDescriptionMeasuring Instruments
I-V curve testThis test evaluates the current-voltage characteristics of PV strings.I-V curve tracer
Infrared thermographic inspectionThe heat generation of PV modules is inspected by the IR thermal camera. By knowing the deviation of the temperature, problems like the bypass diode in the PV arrays can be detected.Infrared Thermal Camera

Additional inspections are also available for inspections outside Category 1 and Category 2.

Additional test

Inspection itemsDescriptionMeasuring Instruments
Voltage to Ground-Resistive Ground SystemMeasure the resistivity according to the technical documentation provided by PV module manufacturer.Loop Impedance Meter
Blocking diode testThis is required for the system using a blocking diode. Check for diode connections and signs of overheating.
Wet insulation testTo validate that the PV modules are safe when exposed to rain or dew, an insulation resistance test is done with the PV modules in a wet state.
Shade evaluationThis is to record the effect of shading by obstacles.


The international standard for testing, documenting, and maintaining grid-connected PV systems is IEC 62446-1. Using the right measuring tools is important for keeping the system running and making sure it is safe. At HIOKI, we offer a variety of measuring instruments to ensure the safety and efficiency of measurements for our users.

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