MNRE Issues Draft Guidelines for Series Testing of Solar Inverters Under 2025 Solar Goods Order

Introduction

The Ministry of New and Renewable Energy (MNRE) has released comprehensive draft guidelines for the series approval of solar photovoltaic (SPV) inverters, establishing a structure for testing laboratory operations and manufacturer compliance under the “Solar Systems, Devices, and Components Goods Order, 2025”.[1]

Explanation (Key Points)

The guidelines establish comprehensive scope coverage, applying to SPV-based off-grid, grid-tied, and hybrid inverters across all operational categories.

Product family classification forms the cornerstone of the series approval system, defined based on maximum configuration of components and sub-assemblies where all models share identical essential hardware and firmware.

Testing protocol differentiation represents a sophisticated approach to balancing efficiency with technical accuracy. For safety and performance testing under standards IS 16221 (Part 2):2015 and IS 16169:2019, only the highest-rated model in a series requires physical testing, with one comprehensive report covering all lower-rated models within the series. However, efficiency testing under standards IS/IEC 61683:1999 and IS 17980:2022 (IEC 62891:2020) requires individual model testing due to potential efficiency variations between models, ensuring that efficiency claims for each variant are accurately verified.

Technical specification requirements ensure consistency and safety across product families. All inverters within a family must maintain identical specifications for critical parameters including input/output voltage, frequency, number of output phases, PCB layout, insulation class, control algorithm, and cabinet design. Any changes in internal components, construction, or firmware that affect safety necessitate complete retesting, ensuring that the series approval concept does not compromise safety standards or regulatory compliance.

Product labeling requirements mandate that each model include essential information such as manufacturer name, model number, input/output ratings, and protection ratings. When fuse ratings are specified, markings must be placed near the fuse holder for easy identification during installation and maintenance.

Documentation requirements are extensive and comprehensive, requiring manufacturers to submit datasheets, single-line diagrams, PCB layouts, Bill of Materials (BOM) lists, firmware versions, and manuals with their test samples. Test laboratories must verify complete documentation submission before beginning tests, ensuring thorough evaluation of submitted products and maintaining comprehensive records for regulatory compliance and quality assurance purposes.

The testing sample requirements specify that two samples of the maximum-rated model must be submitted for safety tests, with testing conducted according to IS 16221 (Part 1 and 2) standards. Laboratories and manufacturers are encouraged to collaborate during critical tests to ensure proper setup and execution.

Failure management provisions provide reasonable accommodation for technical challenges while maintaining quality standards. Manufacturers are allowed to resubmit new samples if initial tests fail, with only the failed test sequence repeated after reviewing component and construction changes. However, only one failure per test sequence is permitted, with further failures resulting in disqualification.

Manufacturing location considerations require that products manufactured at different locations undergo separate testing.

Confidentiality requirements mandate that test laboratories maintain the confidentiality of all submitted technical documents.

The guidelines incorporate BIS registration compliance requirements, specifying that manufacturers with samples already submitted or in the submission process must provide undertakings to comply with the new guidelines.

Conclusion

MNRE’s draft guidelines for series testing of solar inverters establish a comprehensive framework that balances certification efficiency with technical rigor and safety standards. The series approval system enables manufacturers to streamline certification for multiple product variants while maintaining individual efficiency testing requirements that ensure accurate performance claims.