The Ministry of New and Renewable Energy (MNRE) has released draft guidelines for the approval and testing of solar inverters under the Solar Systems, Devices, and Components Goods Order, 2025.

MNRE had released the order in January this year, aiming to enhance the quality and reliability of inverters and other components and increase the adoption of high-performance solar technologies.

It has invited industry stakeholders to share their comments.

Under the guidelines, manufacturers must submit a declaration specifying their products’ series at the time of submitting samples to the test laboratory.

The laboratory will charge testing fees only for the highest-rated inverter model under the IS 16221 (Part II): 2015 and IS 16169: 2019 requirements. A single test report will then be issued for all lower-wattage models in that series, which are covered under the same model family.

Series Guidelines

The firmware can have different limit settings per the series’ model rating. Products with different hardware architectures and firmware functionalities will be tested separately.

All models within a family will have the same rated input/output voltage, frequency, and number of phases at the output.

They will also feature the same printed circuit board (PCB) design and layout, power stage topology, and insulation. Additionally, they must have the same control algorithm and firmware, cabinet design, and class of construction.

If the cabinet design architecture changes between various models within the family, then all the different cabinet designs must be tested or verified for ingress protection.

The maximum-rated inverter within the family will be considered the representative test sample for all the models for safety tests. Manufacturers must provide the product datasheet, International Electrotechnical Commission certification, PCB wiring diagrams, and other relevant documentation.

Inverters must have clear and indelible markings and warning labels that display the manufacturer’s name and trademark, model and serial number, code, input and output voltage, and manufacturing location.

Retesting Guidelines

The inverters will be tested under two sequences.

Sequence 1 includes testing for load transfer, electrical rating, thermal endurance, protection against electrical shock, backfeed voltage protection, single fault conditions, and protection against sonic pressure, fire, and electric shock and energy hazards. It also includes additional testing for grid-interactive inverters.

Sequence 2 includes testing environmental requirements and conditions, physical requirements, mechanical resistance to deflamation, effects of impact or drop, and protection against liquid, chemical, mechanical, and fire hazards.

Both sequences will have a voltage test.

Manufacturers must submit a new sample if the previous one fails Sequence 1 of testing. Only the tests in Sequence 1 will be repeated after the components and construction are verified. Similar procedures will be followed if the test fails in Sequence 2.

Test labs will charge an appropriate retesting fee for all repeat tests.

Pass criteria for solar inverters must adhere to IS 16169 and IS 16221 Part ll wherever applicable.

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