The solar-powered pumping system.

Japan’s National Agriculture and Food Research Organization (NARO) has developed a solar-powered pumping system.

The system is expected to be used in citrus groves on sloping land and uses a solar power generation system and storage battery as a power source for pumping water up to a tank located in a higher place. Water is sent to the tank and slowly discharged toward the roots of citrus fruits like mandarin orange via tubes by utilizing the height difference.

When such an “intravenous irrigation” using a tube is carried out on sloping land, it is usually necessary to use a truck to carry water to a high place or set up large-scale water pumping facilities. However, the newly-developed solar-powered pumping system enables to easily secure a water source in a high place at low costs.

The pumping system combines a small-scale solar power generation system and small pump, lifts water up to a tank installed in a high place and carries out watering with a natural pressure. It pumps up water little by little even when water is not being discharged so that it can periodically supply water at once with a natural pressure.

Also, to prevent battery deterioration, the system performs intermittent operation by pumping water for 15 minutes and stopping operation for 30 minutes.

A standard design of the system is as follows. When 800L of water per day is pumped up to a relative height of 40m by using a 150m-long lifting pipe, it is appropriate to use a 12V pump, two solar panels (nominal maximum output: about 100W (6A) each) and two 90Ah lead-acid batteries, according to NARO.

NARO prepared a manual that simplifies procedures and explains them in an easy-to-understand manner and published it online. The system can be used not only for citrus fruits but for other crops and, therefore, is expected to expand the application of solar electricity at production sites.

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