IEC 62446-1 is the international standard that defines what documentation is handed over when a grid-connected PV system is finished, how it is inspected and which commissioning tests are run on it. It organizes the tests into a category 1 for every system, a category 2 for larger or more complex systems, which adds the I-V curve and thermography, and additional tests for specific project needs. It covers the PV side; the medium-voltage network and the interconnection protections have their own tests.
What IEC 62446-1 is
IEC 62446-1 is part 1 of the IEC 62446 series, Photovoltaic (PV) systems – Requirements for testing, documentation and maintenance. Its full title delimits it: grid-connected systems, documentation, commissioning tests and inspection. According to the official IEC summary, it defines the information and documentation that must be handed to the customer after a grid-connected PV system is installed. It also describes the commissioning tests, the inspection criteria and the documentation that verify the installation is safe and operates correctly.
The current edition is the 2016 one with amendment 1 of 2018. It replaced IEC 62446 of 2009 and widened the scope with more test and inspection regimes for large and complex systems. It is intended for designers and installers, who can use it as a template for the documentation they hand over, and it also serves as the basis for periodic tests during the life of the plant.
The series includes other parts: IEC 62446-2 covers maintenance of grid-connected systems and IEC TS 62446-3 covers infrared thermography of modules and plants in operation.
The four parts of the work
The standard orders commissioning in four blocks that must be closed in order:
- Documentation. System data, drawings, datasheets and manuals handed to the customer
- Inspection. Review of the DC side, the AC side and the labeling
- Testing. Category 1, category 2 or additional tests depending on the system
- Reports. Verification certificate, inspection report and test report
Documentation
The documentation identifies the system and those who designed and installed it. It describes the installation with its electrical drawings and string layout. It gathers the datasheets of modules and inverters and the operation and maintenance instructions. And it records the test results. It is what will allow another person, years later, to understand how the system is built and to repeat the tests to compare.
Inspection
Before measuring, inspect. The DC side is reviewed for protection against electric shock, against the effects of insulation faults and against overcurrents; grounding and equipotential bonding; lightning and surge protection; and selection and installation of equipment. Then the AC side and the labeling are reviewed. No measurement corrects a poor inspection: a connector from two different manufacturers or a cable without mechanical protection do not show up in an insulation test on acceptance day.
Test regime
| Regime | Tests | When it applies |
|---|---|---|
| Category 1 | Earth continuity and equipotential bonding, polarity, string boxes, open-circuit voltage, string current, functional tests, array insulation resistance | Every system |
| Category 2 | The above plus I-V curve of each string and thermographic inspection of the array | Larger or more complex systems |
| Additional tests | Voltage to earth in resistance-grounded systems, blocking diodes, wet insulation, shading assessment | When the case calls for it |
Each test answers a specific question. Polarity, Voc and Isc say whether the string is correctly built. The insulation resistance says whether there is a leakage path to ground. The I-V curve says whether the string delivers what it should. Module thermography says where energy is being dissipated that should not be.
Reports
The standard provides templates for the verification certificate, the inspection report and the array test report. Filling them in with the measured values, the irradiance and temperature conditions at the time and the instrument identification is what turns a test into an auditable record.
What it does not cover
IEC 62446-1 deals with the grid-connected PV system without storage. It does not cover:
- The medium-voltage network and the substation: transformers, switchgear, cables and instrument transformers are tested with the standards of each equipment.
- The protections at the point of interconnection: they are tested by secondary injection according to the local grid code and what the utility requires.
- Storage: a BESS has its own commissioning, described in the BESS commissioning guide.
- Product certification: the inverter anti-islanding is tested under IEC 62116 and certified by the manufacturer, as the anti-islanding protection guide explains.
The complete path of a plant, from the array to the connection with the utility, is in tests to energize a solar plant.
Acceptance criteria
The measurement methods and acceptance criteria are in the standard itself and are not reproduced here. What is general:
- String voltage and current measurements are compared with the values expected from the module datasheet, the number of modules in series and the irradiance and temperature conditions at the time. A single reading says nothing; the comparison between equal strings says a lot.
- The I-V curve is corrected to reference conditions with the procedures of IEC 60891, and its on-site measurement is governed by IEC 61829.
- Thermography requires minimum ambient conditions and qualified personnel, defined in IEC TS 62446-3.
- Instruments must be suitable for the maximum array voltage, which in 1500 V DC systems rules out many general-purpose instruments.
Which systems and levels it applies to
| System | Usual regime | Comment |
|---|---|---|
| Residential, low voltage | Category 1 | Inspection and category 1 are enough in most cases |
| Commercial and industrial, rooftop or ground | Category 1, often with I-V curve | According to the client specification |
| Solar park with a medium-voltage collector network | Category 2 | I-V curves and thermography are part of acceptance |
| Plant with storage | Category 1 or 2 on the PV array | The BESS is commissioned under its own standard |
The array is always low-voltage DC, even if the plant connects at medium or high voltage. What changes with size is the number of strings, the demand of the contract and the importance of leaving a baseline for maintenance.
Relation to local regulations
The installation must meet the electrical code and the utility requirements of the site where it is built, and the design and settings are adapted to them. IEC 62446-1 is not a national technical regulation, but it is the reference that project specifications and manufacturers usually cite for acceptance of the array. The protection tests required by the grid code and the verification by the utility are added to it; they do not replace it.
Before the tests you can organize the records with our commissioning checklist tool.
Equipment for this test
These tests are done with equipment from recognized manufacturers; these guides explain what each one measures. In the quote we recommend the test and the equipment your case needs.
- Metrel MI 3105 and MI 3115: LV installations and PV systems
- PVPM1500X: I-V curve tracer for strings up to 1500 V
We leave your plant ready to operate
Our team does the commissioning of solar plants at medium, high and extra-high voltage: transformer stations, collector network, step-up substation and interconnection protections, with the documentation the utility requires, in Colombia or elsewhere on request. We also do the DC array tests under IEC 62446-1 (I-V curve, insulation resistance, polarity, Voc and Isc, and module thermography, also by drone), so that the records of the whole project arrive complete at energization. Write to us through contact.
Related guides
- Tests to energize a solar plant: IEC 62446-1
- String polarity, Voc and Isc: initial tests
- String I-V curve: what it measures and how to read it
- Insulation resistance in a PV generator
- Thermography of solar panels: IEC TS 62446-3
- BESS commissioning
- Solar plant maintenance according to IEC 62446-2
References
- IEC 62446-1:2016+AMD1:2018, Photovoltaic (PV) systems – Requirements for testing, documentation and maintenance – Part 1: Grid connected systems – Documentation, commissioning tests and inspection.
- IEC TS 62446-3:2017, Photovoltaic (PV) systems – Requirements for testing, documentation and maintenance – Part 3: Photovoltaic modules and plants – Outdoor infrared thermography.
- IEC 60891:2021, Photovoltaic devices – Procedures for temperature and irradiance corrections to measured I-V characteristics.
- IEC 61829:2015, Photovoltaic (PV) array – On-site measurement of current-voltage characteristics.
Frequently asked questions
Which edition of IEC 62446-1 is current?
Edition 1.0 of 2016 with its amendment 1 of 2018, which IEC also publishes as a consolidated version. It replaced IEC 62446 of 2009 and widened the test regimes for larger and more complex systems. Before a project it is advisable to check the IEC catalog for a later edition and to cite the agreed edition in the contract.
When do category 2 tests apply?
Category 1 is the minimum for any system. Category 2 adds the I-V curve of each string and the thermographic inspection, and applies to larger or more complex systems or when the project specification asks for it. The contract decides: in commercial and industrial scale plants it is common for the specification to require category 2.
Does IEC 62446-1 replace the tests the utility requires?
No. IEC 62446-1 covers the PV system: array, string boxes, inverters and their connection. The protections at the point of interconnection are tested according to the local grid code and whatever the utility or grid operator defines, and larger plants have further tests before the system operator. The two things complement each other.