Green Technologies to Facilitate Development of Value Chains
for Perishable Crops and Animal Products

2.1. History and Results

A large 20 kW solar generation and battery storage system was installed on the premises of Rwimbogo Dairy Cooperative's (RDC) Milk Collection Center (MCC) in 2019 through a project funded by IFAD and implemented by Heifer International, as part of the Post-harvest and Agri-business Support Project (PASP) initiated by the Rwanda government. The system worked for some time but stopped functioning due to the absence of maintenance and lack of funds for repair. Therefore, it did not help with the challenges at RDC: major milk losses caused by sudden power cuts and the high cost of electricity that was needed to run their bulk coolers.

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While conducting a Needs Assessment for utilizing small scale fridges for evening milk in late 2020, the GreenTech Project Manager and counterpart from Clean Energy Technologies (CET) become aware of the non-operating Solar + Storage system incorporating 88 ground mounted panels. The panels were examined and established to produce about 20 kW of peak power, supplied to a hybrid inverter/charge controller that stored the power in a bank of lead-acid batteries, which supplied the power to large bulk milk coolers. When it functioned, the biggest challenge of the system was that it operated manually. When the sun was up, the system was turned on manually to run the coolers and when sun was not available the system was turned off to use grid power, which frequently went down and caused major milk losses to the RDC.

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CET further examined the non-functioning system and found out that the batteries and inverter/charger were damaged beyond repair. The finding was shared with the RDC board and efforts were made to reach the inverter manufacturer in China for replacement, but no trace of the company was found. In several interactions and meetings conducted by CET with RDC members, the issue of reviving the non-functioning Solar + Storage system came up frequently as a priority to avert the major milk losses and the high cost of grid electricity. These challenges then were presented to SunDanzer. With the full support of IFAD, an ensuing proposal to rehabilitate the system was approved and folded into the GreenTech program as an add-on project. The proposal included not only replacing the power electronics, but also expanding the size of the array to 40 KW and the battery bank so that the dairy could run the coolers off-grid both day and night as well as have extra capacity for adding another bulk milk cooler in the future.

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Following the approval of the proposal to resurrect the dead system, an amended contract was signed on April 1, 2022, taking the same approach as for the bulk milk cooling project. One of the key conditions of the agreement was the cooperative had to commit to a down payment of 10% of the total cost for rehabilitating the system, as their way of demonstrating ownership. The amount was added to the 10% commitment that the cooperative had made initially made towards the bulk milk project. CET again loaned the 10% to the RDC.

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The prediction for future expansion of the cooperative business proved to be accurate. As the progress of the refurbishment of the solar system was proceeding, the cooperative acquired a new cooler, with a capacity of 2,500 liters in addition to the already existing coolers (that had a total capacity of 5,500 liters). This validated the necessity for the additional 20 kW of solar panels that were installed on the rooftop of the structures at the compound of the MCC. The Solar + Storage system was designed to accommodate cooling capacity of about 10,000 liters, which enables the system still able to support future expansion of another 2,000 liters.

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All the solar power equipment could be readily sourced in Kenya and the installation was commissioned in May. The Solar+Storage system was upgraded to 40 kW with an additional roof mounted array of Amerisolar 450 watt modules, a pair of 20 kW Azzurro hybrid inverters integrated with 16 Weco 5.3 kWh Lithium batteries. It is designed to run in total off-grid mode or accept power from the grid to add to the power generated on-site (as back-up or for future expansion at the dairy). The entire cost for rehabilitating the solar system was about $80,000 USD, used to purchase equipment, materials and pay for the technical labor for installation.

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2.2. Current Status

As of March 2023, the Solar + Storage system has operated totally off-grid, proving to be a successful intervention in reducing the power costs for running the dairy and eliminating losses. On average the dairy was paying about $600 USD per month for grid power, which is being greatly offset, hence achieving one of the intended goals of the project of reducing the high cost of grid power and using the savings to repay the loans made by CET. However, the connection to grid back-up is still manual, awaiting an upgrade of the local grid to 3 phase electricity. This has caused some problems in the rainy season when the system needs to be supplemented by the grid and some milk losses have occurred. There were also software issues with the system that took days to resolve, resulting in milk losses. However, with the provision of a relatively constant and reliable source of power for cooling milk, the large losses that occurred when grid power went on and off have been largely curtailed. An analysis conducted by the RDC management in early 2022 showed that 1,000s of liters and 100s of USD were lost every month due to power failures and rejected milk. Losses now are minimal.

 

The Cooperative Manager recently reported that the system at the MCC was not equipped with lighting protection. The power electronics are surge protected. However, having a lightning for general protection of the MCC would be desirable. The GreenTech Project Manager is investigating possible ways to fund upgrading the protection system.

 

Also, an analysis of RDC’s production and losses before and after the system installation have been requested.jobs and increase revenues.