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Cycle 7 (2018 Deadline)

Off-grid, clean energy cooling for affordable storage of perishables for bottom-of-the-pyramid farmers

PI: Sangeeta Chopra (, Indian Council of Agricultural Research-Indian Agricultural Research Institute (ICAR-IARI)
U.S. Partner: Norbert Mueller and co-partner Randall Beaudry, Michigan State University
Dates:  January 2019 - December 2022

Project Website:

Project Overview

A stand-alone, batteryless, off-grid, solar-refrigerated evaporatively-cooled (SREC) structure for storage of perishables has not previously been field evaluated by smallholder base-of-the-pyramid (BOP) farmers. The SREC chamber can easily achieve daytime temperatures as low as ~5-10 °C when the daily maximum temperature outside is approximately 45 °C. This technology promises a meaningful contribution to the capacity and stability of the BOP farmer. The innovations incorporated into the SREC structure are many: a design that can be largely self-built and permits staged construction and investment; the use of passive evaporation of water from the chamber walls for partial cooling both day and night, thereby reducing refrigeration load and cost; the use of a split evaporator coil system to shunt cooling to a thermal reservoir; the deployment of a new inverter technology with a secure power supply and integrated controls to maximize solar collector efficiency; the use of a cold water reservoir to provide low-cost thermal storage instead of using batteries for overnight cooling (reducing environmental impact, operational risks, initial capital, and maintenance costs); the deployment of an extremely large surface in the chamber to maximize cooling with a minimal temperature differential, thereby increasing humidity and minimizing perishable desiccation; the use of a dedicated relay circuit to ensure automatic start-up following overnight shutdown; and no dependence on electrical grid for cooling. Despite the novelty of the structure, it can be self-built by farmers with inexpensive locally available materials, minimizing extra labor costs and initial investment requirements. The specialized components required, like solar panels, inverters, and refrigeration systems, are readily available in India. This project is aimed at replicating initial technical successes by transitioning to field trials by farmers. The researchers will evaluate the amount of energy collected and converted to refrigeration, measure impact on the quality of perishables stored, determine the value to farmer households, and assess the impact on local and regional markets.

Deploying innovative off-grid batteryless SREC structures/chambers at farmers’ fields in villages in three hot and dry states of India will have several important impacts. This innovation will help India's transition to a low emission economy by adding decentralized solar PV capacity. Having access to on-farm cold storage will increase incomes for BOP farmers by avoiding distress sales, reducing spoilage, and enabling pre-processing of perishables. Adopters of SREC technology will keep produce cool without grid electricity, which frequently fails. Market panic following grid failures is avoided and market confidence and control improved. Higher profits will improve quality of life, increase purchasing power, support higher education for women and children and improve household affluence. Education is another important part of this work. Farmers and local tradesmen will be trained to build SREC chambers themselves, thereby improving community capabilities and opening up new opportunities for financial growth. The farmers will be educated on opportunities for light processing of perishables (e.g., pod stripping, pea or bean shelling, packaging) and will be able to run small processing machinery directly from solar panels. Additionally, extension professionals will be trained on the fundamentals of construction and use of this technology and will be encouraged to act as agents of change.

Summary of Recent Activities

In April 2022, Dr. Sangeeta Chopra and U.S. co-partner Dr. Randolph Beaudry visited the Farm SunFridges (FSF) built at Delhi, Haryana, and Rajasthan. Their first visit was to the FSF (new frame assembly design) at Cullakpur, Delhi. They found the young farmer Abhishek, along with the farmer producer organization (FPO) he manages, using the FSF to store cabbage, tomatoes, and spinach and making a profit from having it on his farm. A collection center and light processing platform have been constructed adjacent to the FSF, and the farmer is buying, storing and selling his produce from the FSF facility. The researchers interviewed the farmer and other members of the FPO and learned that the FSF was working better than their expectations. The SunFridge at Cullakpur is working very well, with low temperatures ranging from 0 to 5 °C, when there was no loading/ unloading of produce, and 10 to 15 °C when there was significant product movement. The cold room environment has permitted growers to enter the premium market segment for sale of spinach (washed, trimmed and bound in bunches) and red cabbage (long-term storage), and the facility is turning a profit.

The next facility visited was the FSF at Chamrara, Haryana, which was found to be working with fair temperature control (10 to 15 °C at the time of the visit). The facility underperformed slightly, likely because its solar panels were not washed frequently. The farmer is around 80 years old and said he thought the facility was working very well. He has also started a processing plant after the FSF was built, and he is happy with his processing and storage business. He and some nearby growers are using the FSF for storage of produce (potatoes, at the time of the visit). More could be done to fully utilize the capabilities of the cold storage to access higher value markets.

The FSF on the IARI Exhibition Ground has been running for a little over one year and was filled with 1.5 tons of potatoes as a research study by a Master’s student. The FSF is working well and is also serving as a demonstration unit for policy makers, growers, and students visiting IARI.

7-360 Chopra SREC Picholiya
The fully constructed and operational SREC chamber in the village of Picholiya (Photo Cred: Dr. Chopra).

Lastly, Dr. Chopra and Dr. Beaudry visited the FSF installation at Picholiya (built in March 2020) and found the system shut down, not in use, and in disrepair. The inside of the FSF was unkempt and had rodents and some very old produce still inside. The researchers learned from farm hands living nearby that the director of the business responsible for upkeep and usage of the FSF was not using the structure for perishables storage. Instead, he was using it for personal purposes like dining inside with his friends. The FSF had worked well earlier while a field worker was looking after it and sending data daily to the research team. Unfortunately, the worker left due to not receiving his wages regularly, and the business director also failed to notify the researchers when the facility stopped operating. The processing facility, which was already existing on the farm when the FSF was built, was also non-functional. Given these conditions and the lack of interest by the farmer and local managing partner in using the FSF, the PI and her colleague dismantled the unit and retrieved the valuable components that could be shipped back to IARI for other use (solar panels, refrigeration system, MPP inverter, solar adaptive controller, wiring, instrument gauges, and cabinets). They will be used either to build a new FSF at an interested farming community willing to invest some of their own resources in the project or to build a larger FSF facility at IARI (as requested by local farmers) to continue the research.

Meanwhile, the FSF at Cullakpur has become the hub of farming activities by the FPO Adhirayansh Organics Producer Company Pvt. Ltd. The 175 farmer groups of the FPO have been able to enter a premium spinach market and are making a profit by virtue of having an FSF on their field. They have a collection center next to the FSF in support of its operation. The farmers have constructed a floor and a dock on the outside of the SunFridge. In addition to field-grown perishables, the growers plan to store fresh-cut fruits and vegetables in the FSF. They are selling their produce directly, using a B2B model, to Swiggy and Zomato and operators with mobile apps who supply fresh produce to urban areas. The data on currents, voltages, temperature, and relative humidity are being collected remotely and analyzed. The farmers are also maintaining a logbook and supplying data about the items being stored in the FSF.

Supplemental Funds

With funding provided through a PEER Research to Action supplement, Dr. Chopra and her colleagues are also making progress on a Farm SunFridge construction manual. Such a manual has been requested by farmers and policy makers alike. In addition, they are a bankable detailed project report with an economic analysis so that interested parties may obtain bank loans for building the structure. Dr. Chopra is visiting Michigan State University from early November to mid-December 2022, during which she will be working with Dr. Beaudry on finishing the manual and preparing a case study and other publications on their project.


Chopra, S., N. Mueller, D. Dhingra, I. Mani, T. Kaushik, A. Kumar, and R. Beaudry. 2022. A mathematical description of evaporative cooling potential for perishables storage in India. Postharvest Biology and Technology 183:111727

Mahangade, P.S., I. Mani, R. Beaudry, N. Müller, and S. Chopra. 2020. Using amaranth as a model plant for evaluating imperfect storages: assessment of solar-refrigerated and evaporatively-cooled structures in India. HortScience 55,

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