MNRE releases draft guidelines for SPV inverter testing

The Ministry of New and Renewable Energy (MNRE) has released draft guidelines for series approval of solar photovoltaic (SPV) inverters. These are meant for testing in designated labs under the “Solar Systems, Devices and Components Goods Order, 2025.”

Issued on 23 June 2025, the guidelines aim to help test labs and manufacturers define product families. This will streamline testing and certification for SPV-based off-grid, grid-tied, and hybrid inverters.

Stakeholders are invited to send comments within 15 days of notification to NISE and MNRE.

Product family and test procedures

A product family is defined based on common hardware, firmware, and internal components. The highest-rated model in a family will be tested as a representative unit for safety and islanding standards: IS 16221 Part 2: 2015 and IS 16169: 2019.

However, for efficiency standards—IS/IEC 61683: 1999 and IS 17980: 2022—each model will undergo testing individually.

Test labs will apply fees only for the highest-rated model for the common standards. Model-wise fees and reports will apply for efficiency-related standards.

Submission and documentation requirements

Manufacturers are expected to provide detailed documentation, including schematics, PCB layouts, firmware details, product datasheets, user manuals, and safety certificates. PCB samples and accessories like mounting kits are also to be included.

Labs will not proceed without this information. For samples already submitted or in transit, manufacturers are expected to provide an undertaking confirming compliance with the draft.

Construction and labeling requirements

All inverters in a product family should have the same input/output voltage, frequency, number of phases, PCB layout, control firmware, and cabinet design. Differences in cabinet design will require IP verification through NABL-approved or equivalent accredited labs.

Labels should display the manufacturer’s name, model number, serial code, voltage, frequency, current details, and IP rating, as per IS 16221 Part 2, Clause 5.

Sample selection and retesting protocol

Two units of the highest-rated inverter in a series are to be submitted. One will undergo testing. In case of a test failure, a new unit is to be submitted, and tests will restart for the failed sequence.

IS 16169 will not be tested for standalone or off-grid inverters.

Branding and manufacturing sites

If a single model is sold under multiple brands, product labels for each brand are to be included in the test report. Testing can be limited to the representative model based on manufacturer declarations. Inverters from different manufacturing locations will require separate testing.

Confidentiality of submitted data will be maintained by the test labs. These draft guidelines will take effect upon notification by MNRE.