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The Ministry of New and Renewable Energy has invited comments from stakeholders on the draft revised specifications for solar pump controllers. The invitation was issued by its Standards and Quality Control Division through Office Memorandum File No. 313-12/2/2026-S&QC, dated 12 August 2026.
The draft, prepared by the National Institute of Solar Energy (NISE), proposes detailed performance, safety, testing, and environmental requirements for solar photovoltaic water-pumping controllers. It also introduces a wider role for these controllers by covering multifunction applications, battery storage and grid-interactive operation.
According to the office memorandum, comments may be submitted by 28 August 2026. This is a consultation deadline, not a deadline for complying with the proposed technical requirements.
The proposal may be particularly relevant to solar pump controller manufacturers, PM-KUSUM vendors, system integrators, component suppliers, battery-system developers, testing laboratories, state implementing agencies and businesses involved in agricultural solar-energy equipment.
| Particular | Verified details |
| Issuing authority | Ministry of New and Renewable Energy, Standards and Quality Control Division |
| Technical draft prepared by | National Institute of Solar Energy |
| Document type | Office memorandum inviting comments, accompanied by draft revised technical specifications |
| File number | 313-12/2/2026-S&QC |
| Date of issue | 12 August 2026 |
| Legal status | Draft issued for stakeholder consultation |
| Effective date | Not expressly specified |
| Consultation deadline in office memorandum | 28 August 2026 |
| Compliance deadline | Not applicable at the draft-consultation stage |
| Proposed standard title | Solar Photovoltaic Water Pumping Controllers - Performance, Safety and Test Requirements |
| Maximum covered PV input voltage | Up to 1,000 V DC |
| Applications covered | Agricultural, potable-water, community-water and industrial solar pumping applications |
| Controller modes covered | Off-grid, off-grid with storage, multifunction, grid-feeding and grid-interactive |
| Supported motor technologies | Induction, PMSM and BLDC motors |
| Main stakeholders | Manufacturers, system integrators, testing laboratories, PM-KUSUM vendors and implementing agencies |
| Main development | Proposed standardisation of controller safety, efficiency, interoperability, monitoring and testing |
| Fees or penalties | Not expressly specified |
The official MNRE notice confirms that the Ministry has invited comments on the draft. However, the webpage displays an âEnd Dateâ of 11 October 2026, while the attached office memorandum expressly asks stakeholders to submit comments by 28 August 2026. Unless MNRE issues a clarification, stakeholders should work with the earlier date stated in the signed office memorandum.
These are only proposed requirements at this point. The draft is still open for consultation and does not create any new compliance obligation yet.
The draft repeatedly uses expressions such as âshall,â âshouldâ and âmay.â These expressions describe how the proposed framework is intended to operate if it is finalised. They do not, by themselves, make the draft legally binding during the consultation stage.
The document does not expressly specify:
These matters may need to be addressed when MNRE finalises the specification or incorporates it into PM-KUSUM guidelines, procurement documents, quality-control requirements or another binding instrument.
The proposal is connected with the technical framework for solar photovoltaic water pumping systems deployed under MNRE programmes, including PM-KUSUM. Existing MNRE specifications for solar photovoltaic water pumping systems already address matters such as controller capacity, MPPT, enclosure protection, remote monitoring and pump-system safeguards.
The new draft focuses specifically on solar pump controllers and proposes a more detailed framework for controller performance, safety, environmental resistance, power quality and testing.
Normative references
The draft identifies the following as normative references, meaning that their relevant provisions are intended to form part of the proposed technical requirements:
The draft states that the latest editions of these standards would apply.
Informative references
The draft separately classifies the following as informative references:
An informative reference is included to provide additional context or guidance. It does not, by itself, create a separate requirement that businesses must follow unless the final document specifically makes it mandatory.
The draft applies to solar photovoltaic water pumping controllers intended for:
It covers controllers used for:
The proposed scope extends to controllers with:
The proposal is therefore wider than a controller specification limited to agricultural irrigation. It could influence product design for community water, rural-energy, industrial pumping and multifunction farm-energy systems.
The proposed configurations cover different operating needs, from basic solar pumping to battery-backed systems and grid-connected applications:
The core controller converts DC electricity from a solar PV array into an electrical output suitable for operating a pump motor. It is also expected to perform control, protection, MPPT and monitoring functions.
Annexure I proposes an off-grid multifunction controller that can use solar power for pumping and other agricultural or household applications without a dedicated battery.
The proposed configuration contains four outputs:
The annexure describes two three-phase outputs rated at 400 V and two single-phase outputs rated at 220 V, 50 Hz.
Although the annexure refers to four independent outputs, the main body states that only one selected load should operate at a time. The controller interface must provide load selection and electrical and operational interlocking between the outputs.
The draft permits a dedicated battery energy storage system to be integrated with the controller.
The proposed battery bank would connect to the DC bus through a Dual Active Bridge converter. This arrangement allows electricity to flow in both directions between the battery and the controller.
A storage-enabled system could:
For functional verification, the solar PV array, controller, battery bank and DAB converter would be tested as an integrated system. For performance evaluation, the proposal requires separate assessment in solar-only, and battery-only modes.
The draft also describes a hybrid multifunction controller capable of interacting with the utility grid.
Depending on the applicable regulatory framework, such a controller could:
The proposal does not create an automatic right to export electricity. Grid export, net metering and interconnection would remain subject to applicable electricity regulations, distribution-company requirements, state rules and grid codes.
The proposed requirements set clear expectations for the controllerâs performance, identification, safety markings and operating conditions:
1. Controller rating
The manufacturer would be required to declare the controllerâs rated power.
The proposed controller rating must be equal to or greater than the peak power of the connected PV array, as specified for the relevant water pumping system under MNRE specifications and IS 17018-1.
The controller would also have to deliver its marked output power or rated current continuously for at least two hours while operating the pump at peak rated voltage and frequency. During this test, it should not:
2. Rating plate and permanent markings
The controller would require a permanent, weatherproof rating plate. The draft proposes:
The rating plate would include:
The draft further identifies the controller as:
Proposed safety markings include warnings relating to PV disconnection, protective earthing, hot surfaces and hazardous DC voltage.
The draft places considerable emphasis on wider input-voltage operation. This is intended to make controllers more adaptable to changes in PV module size, rating, voltage and efficiency.
Manufacturers would declare minimum, nominal and maximum input-voltage values. Testing would then be conducted at:
For all motor-pump sets, the controller would have to operate at:
The controller would be expected to deliver rated power at each of these three voltage levels.
The draft also proposes that the controller should continue operating where one PV module is added or removed, including variations associated with bypass-diode activation.
Controllers rated at 10 kVA or above would require multi-channel MPPT to reduce array mismatch losses and improve energy harvesting.
Efficiency is where a solar controller proves its real value. The proposed requirements focus on reducing power losses, improving MPPT performance and making sure more of the available solar energy reaches the connected load.
At or above 80% of rated PV power under standard test conditions, the draft proposes the following minimum conversion efficiency:
| Controller capacity | Minimum conversion efficiency |
| Below 5 kVA or 5 HP | 93% |
| 5 kVA or 5 HP and above | 94% |
These limits would apply regardless of whether the controller uses a single-stage or two-stage design.
Static MPPT efficiency measures how effectively a controller extracts available PV power under stable operating conditions.
The draft proposes a minimum static MPPT efficiency of 98% across 10% to 100% of rated PV input power.
Dynamic MPPT efficiency measures performance while solar irradiance is changing.
The draft proposes a minimum dynamic MPPT efficiency of 97% under hot-day and cold-day profiles specified under IS 17018-1.
The proposed minimum overall efficiency at or above 80% of rated PV input power is:
| Controller Rating | Conversion Efficiency | MPPT Efficiency | Minimum Overall Efficiency |
| Below 5 HP | At least 93% | At least 97% | At least 90.2% |
| 5 HP and above | At least 94% | At least 97% | At least 91.2% |
Testing would be carried out at minimum, nominal and 90% of maximum DC input voltage, with measurements at 10%, 25%, 50%, 75% and 100% input-power levels.
The draft allows controllers to use constant V/f control, flux control or an equivalent manufacturer-developed control algorithm.
The controller should provide stable operation from zero speed to rated speed.
For a universal or multifunction solar pump controller used with equipment such as flour mills and chaff cutters, the draft proposes a minimum torque-overload capability of 150% for 30 seconds.
The overload test may be conducted by:
Annexure II also allows laboratories to use simulated loads instead of procuring every type of farm equipment. Dynamometers, motor arrangements, resistive loads and programmable load banks may be used to recreate relevant operating conditions.
If the applied torque exceeds the permissible limit, the controller should initiate protective action and generate a torque-overload alarm or fault indication.
Poor power quality can quietly damage motors, increase heating and shorten equipment life. The proposed requirements aim to keep the controllerâs output within safe limits and maintain reliable motor performance under different operating conditions.
1. Sinusoidal motor output
For induction and PMSM motors operating with a sinusoidal output the proposed limits are:
These requirements are intended to reduce motor heating, insulation stress, torque ripple and long-term performance problems.
2. Intentionally non-sinusoidal output
For controllers designed to supply a non-sinusoidal waveform to dedicated motor loads, the draft proposes:
3. Voltage spikes
For a 415 V motor system with more than 60 metres of cable, the proposed peak voltage at the motor terminals must not exceed 620 V. The spike duration must remain below 1 microsecond.
The draft also lays down safety checks for high-voltage electrical parts. These cover insulation, leakage current and stored charge, to reduce the risk of electric shock during use or maintenance.
1. Insulation withstand
The draft proposes humidity preconditioning before dielectric testing. The controller would be exposed to 92% relative humidity at 40°C for 48 hours.
The proposed dielectric test voltage is calculated as:
Two times the maximum PV input voltage plus 1,000 V AC
The voltage would be applied at 50 Hz for one minute.
The proposed acceptance criteria are:
2. Touch-current Limits
During rated operation, the proposed limits are:
3. Stored-energy Discharge
After disconnecting the PV input, the voltage at the PV terminals must fall below 60 V within 10 seconds.
This requirement is intended to reduce the risk of electric shock during servicing or maintenance.
Solar pump controllers are commonly installed in dusty fields and exposed to humidity, rain and high temperatures. The draft therefore classifies the equipment for Pollution Degree 3 and Overvoltage Category III conditions.
1. IP65 enclosure test
The draft proposes both dust and water-jet testing.
For dust protection, the controller would be exposed to circulating talcum powder at 2 kg/mÂł for approximately eight hours, with a negative internal pressure of 2 kPa.
For water protection, jets would be directed from multiple angles at a distance of 2.5 to 3 metres. The equipment would then be drained before inspection.
The controller would pass where:
2. Humidity Exposure
The proposed humidity preconditioning is:
3. Impulse-voltage withstand
The proposed impulse test uses a 6 kV peak impulse:
The controller would have to show no flashover, puncture, excessive leakage or component disruption.
The proposed tests focus on safe operation during heat, faults and abnormal conditions, with added safeguards for battery-based systems.
The controller would operate for four hours under rated conditions. Proposed maximum temperatures include:
| Component | Maximum temperature |
| Touchable metal surface | 65°C |
| Touchable metal surface | 75°C |
| Operator controls | 55°C |
| Transformer or motor windings | 155°C for Class F |
| Semiconductors | Manufacturerâs datasheet limit |
The draft proposes blocking controller vents or heat sinks with surgical cotton and operating the controller at full load for seven hours.
The proposed acceptance conditions are:
Motor terminals would be shorted under full PV input. The test would record current, clearing time and controller response.
The controller would need to remain stable or activate protection without causing fire or enclosure deformation.
The controller should detect pump operation without adequate water and display a dry-run error.
The controller should detect an open PV circuit and reverse polarity and provide a corresponding fault indication.
Where a controller contains a battery-charging function, the draft proposes additional compliance with IS 16797:2019 and IEC 62509:2010.
The proposed battery provisions include:
Annexure II contains blank spaces for manufacturer-specific charging currents, voltage cut-offs and set points. These values would need to be declared and verified for the particular battery system.
For grid-connected operation, the proposed hybrid controller would have to meet the anti-islanding requirements of IEC 62116 and the applicable safety provisions of IS 16221 Part 2.
If the utility grid fails, the controller would have to:
Before connecting or reconnecting, the controller would need to synchronise its voltage, frequency and phase angle with the grid in accordance with IEC 61727 and the applicable Indian grid code.
These technical provisions do not replace state-level interconnection, net-metering or distribution-licensee requirements.
The draft proposes integration with a remote monitoring system using GSM or GPRS and geotagging.
The controller display and remote system would provide information such as:
The draft does not expressly prescribe data-retention periods, cybersecurity controls, data ownership, communication charges, portal integration or privacy safeguards for this proposed controller-specific framework. These areas may require clarification before final implementation.
The draft includes a sequential testing structure covering:
The table itself skips sequence number 14 and labels the last tests as 15 and 16. This appears to be a numbering issue rather than evidence of an omitted technical requirement, but it should be clarified in the final version.
The draft also proposes a post-test protocol after every test. This includes dielectric verification, insulation-resistance measurement, visual inspection and confirmation that the controller can still perform its basic PV-to-motor function.
Annexure II provides a testing format for an off-grid multifunction controller.
The laboratory would verify:
Total circuit protection
Actual flour mills, chaff cutters, freezers and farm equipment would not necessarily need to be installed in the laboratory. Equivalent loading could be simulated through motors, dynamometers, programmable loads and load banks.
The proposed changes could affect manufacturers, testing bodies, system integrators and end users across the solar and rural-energy ecosystem.
1. Solar Pump Controller Manufacturers
Manufacturers may need to review their hardware, firmware, enclosure, rating plate and thermal design against the proposed requirements.
The wider voltage range, efficiency limits, IP65 tests, impulse withstand, multifunction outputs and detailed type-test sequence could require design changes or additional evidence.
2. PM-KUSUM Vendors and System Integrators
Vendors may need to ensure that controller ratings match the connected PV array rather than only the pumpâs motor rating.
They may also need to verify compatibility among:
3. Testing Laboratories
Testing laboratories could see increased demand for combined electrical, environmental, performance and functional testing.
However, laboratories may require additional equipment for:
4. Battery and Power-electronics Businesses
The proposed storage configuration may create opportunities for battery manufacturers, DAB converter developers, energy-management providers and rural-energy solution companies.
These opportunities remain dependent on the final specification, scheme design and procurement framework.
5. Farmers and Rural Users
If implemented effectively, multifunction controllers could help farmers use solar electricity for more than irrigation.
Potential applications include:
The practical benefit would depend on system cost, available PV capacity, load compatibility, safe wiring, maintenance support and operating rules.
Stakeholders should consider raising the following points during consultation:
1. Different dates on the Memorandum and MNRE Webpage
The office memorandum asks for comments by 28 August 2026. The MNRE notice webpage displays an end date of 11 October 2026. The Ministry may need to clarify the controlling consultation deadline.
2. Output-voltage Differences
Annexure I refers to 220 V single-phase output, while Annexure II refers to 230 V single-phase output. The document also refers to 400 V, 415 V and up to 440 V in different contexts.
These values may describe different operating or test conditions, but the final specification should explain their relationship clearly.
3. Different Distortion Limits
The main body permits up to 10% THD for sinusoidal output and up to 40% for intentionally non-sinusoidal motor output. Annexure II separately states that ripple and distortion should be below 5% after 25% loading.
The final document should explain whether the 5% requirement applies to voltage ripple, waveform distortion, a particular output or a separate measurement.
4. Insulation-resistance Inconsistency
Clause 8.1 requires insulation resistance greater than 100 MΩ at 500 V DC after dielectric testing. The post-test protocol later refers to a value greater than 50 MΩ.
A single acceptance limit should be specified.
5. Section and Test Numbering
The draft contains repeated or missing numbering, including:
Renumbering would improve usability and prevent test-reporting errors.
6. Cross-reference Issues
The humidity section refers to dielectric testing under clause 6.1, although the relevant insulation test appears under clause 8.1.
Cross-references should be checked before finalisation.
7. Four Outputs versus One Operating Load
Annexure I describes four independent outputs, while the main body states that only one load may operate at a time. The final specification should clarify whether âindependentâ refers only to separate terminals and software configurations.
8. Testing and Certification Mechanism
The draft requires independent testing but does not expressly specify:
9. Treatment of Existing Controllers
The draft does not explain how a final specification would affect:
A transition or grandfathering framework may therefore be necessary.
10. Data and Remote-monitoring Governance
The proposal lists extensive operational and geolocation data but does not expressly address cybersecurity, data ownership, access rights, retention, communication failure or portal interoperability.
11. Grid-interconnection Dependencies
The hybrid model refers to grid import, export, net metering and behind-the-meter operation. The final document should clearly distinguish controller capability from the separate regulatory permission required for grid connection and export.
The office memorandum invites comments from stakeholders by 28 August 2026.
Comments may be sent to:
The memorandum does not prescribe a specific comment format. A structured clause-wise submission would make stakeholder feedback easier to evaluate.
A useful comment matrix may contain:
Draft clause- Existing wording- Issue identified- Suggested wording- Technical justification
Stakeholders should support comments with test data, applicable standards, field-performance evidence, safety analysis or cost implications wherever possible.
1. Conduct an Applicability Review
Determine which controller models, motor technologies, operating modes and product configurations fall within the proposed scope.
2. Compare Existing Products with the Draft
Prepare a technical gap assessment covering:
3. Review Available Test Evidence
Identify which proposed requirements are already covered by current test reports and which would require fresh testing.
4. Assess Laboratory Capability
Consult testing laboratories about equipment, accreditation scope, sample requirements, test duration and likely capacity constraints.
5. Identify Unclear or Conflicting Provisions
Document any technical ambiguity that could affect design, testing, cost, procurement or interoperability.
6. Submit Evidence-based Comments
Send clause-wise comments before the deadline stated in the office memorandum. Avoid limiting the submission to broad commercial objections.
7. Avoid Premature Compliance Claims
Do not market a product as compliant with a final MNRE 2026 specification until the draft is finalised and the applicable conformity route is established.
8. Monitor the final Version
Track MNRE notices for a final specification, revised draft, implementation timeline, transition arrangements or scheme-level adoption.
Businesses involved in solar pumping and rural-energy systems may require both regulatory interpretation and technical coordination to respond effectively to the draft.
Corpseed can assist with:
The purpose of this support is to help manufacturers and vendors understand the proposal, identify genuine technical gaps and prepare an evidence-based response. Final acceptance, testing, certification or approval would remain subject to the competent authority and applicable laboratory or scheme procedures.
Businesses that manufacture, supply, test or integrate solar pump controllers can seek specialised solar pump technical compliance consulting before submitting comments or planning product changes.
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