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NISE Proposes Revised Solar Pump Controller Specifications with Higher Efficiency, BESS Integration

The National Institute of Solar Energy’s draft revised specifications propose higher efficiency benchmarks, wider PV operating ranges, support for battery storage and grid interaction, and multifunctional use of solar pump controllers to enhance the utilisation and reliability of PM-KUSUM solar assets.

August 13, 2026. By Mrinmoy Dey

The National Institute of Solar Energy (NISE) has proposed revised specifications for solar pump controllers aimed at improving efficiency, expanding their use beyond irrigation and enabling integration with battery storage and the grid.

The draft proposes wider PV voltage operating ranges, stringent MPPT and conversion-efficiency benchmarks, multi-function operation for agricultural and domestic loads, BESS integration and hybrid grid import-export capabilities to improve utilisation of solar assets deployed under PM-KUSUM.

The proposed specification covers solar PV water pumping controllers for off-grid operation, with or without storage, multi-function applications, grid-feeding and grid-interactive pumping systems. It applies to agricultural, potable water, community water and industrial applications and covers controllers with PV input voltages of up to 1,000 V DC. The controllers would support single- and three-phase outputs and motor technologies including induction, permanent magnet synchronous (PMSM) and brushless DC (BLDC) motors.

A key proposal is to make controllers adaptable to changing PV module technologies and configurations. It would require MPPT and sufficient PV input voltage flexibility to accommodate changes caused by temperature, irradiance, module ageing and evolving module ratings. Controllers would need to operate at nominal PV voltage ±15 percent while delivering rated power. Systems rated at 10 kVA or higher would also require multi-channel MPPT to reduce mismatch losses and improve solar energy harvesting.

The draft sets minimum efficiency benchmarks for controllers. At or above 80 percent of rated STC PV power, static power conversion efficiency would need to be at least 94 percent for systems rated at 5 kVA/5 HP and above and 93 percent for systems below 5 kVA/5 HP. Static MPPT efficiency would need to reach 98 percent, while dynamic MPPT efficiency under changing irradiance conditions would have to be at least 97 percent. Minimum overall system efficiency is specified at 90.2 percent for controllers below 5 HP and 91.2 percent for those rated at 5 HP and above.

The proposed framework also seeks to turn solar pump controllers into multi-function rural energy platforms. An off-grid multi-function controller could operate agricultural pumps alongside other farm machinery and domestic loads. The proposed architecture includes two three-phase outputs rated at 400 V and two single-phase outputs rated at 220 V, 50 Hz. Compatible applications include chaff cutters, atta chakkis, farm equipment, cold storage, pumps and domestic loads.

For universal solar pump controllers supporting other agricultural loads, the draft proposes a 150 percent torque overload capability for 30 seconds. This is intended to enable reliable operation of varying agricultural loads while protecting the controller and motor system.

The draft additionally provides for integration with battery energy storage systems. A battery bank could be connected to the controller's DC bus through a bidirectional Dual Active Bridge converter, allowing the system to supply power during low solar generation and non-sunshine hours. Performance would be evaluated in both solar-only and battery-only modes, along with testing of the complete PV-battery-controller system.

Hybrid controllers could also import electricity from and export surplus solar power to the utility grid. The system would manage power flows among PV, battery storage, the grid and agricultural and domestic loads. For grid-connected operation, the controller would have to disconnect from the grid within two seconds following a grid failure and meet applicable anti-islanding and synchronisation requirements.

The specifications include extensive safety and environmental requirements, including IP65 or higher enclosure protection, protection against electric shock, humidity testing at 92 percent RH and 40°C for 48 hours, and a 6 kV impulse-voltage withstand test. Power quality requirements would limit voltage THD to 10 percent for sinusoidal motor outputs.

The draft also mandates GSM/GPRS-based remote monitoring and geo-tagging, covering parameters such as pump status, faults, PV voltage, generation, operating hours, water discharge and peak power.

Overall, the proposed revisions seek to improve the efficiency, safety, flexibility and long-term utilisation of solar pumping systems, particularly by enabling installed PM-KUSUM assets to support a broader range of agricultural, domestic and energy applications beyond conventional irrigation.

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Standards & Certifications

National Institute of Solar Energy

Solar Pump Controller

Solar Pump Controller specifications

PM KUSUM Yojana

BESS in PM KUSUM