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An international research group has proposed a low-cost testing methodology for solar water pumping systems that can reportedly improve access to water in developing countries. The novel approach allows for continuous monitoring of wells without additional fuel costs or interruptions to water supply.
An international research team has proposed a new test method for photovoltaic water pumping systems (PVWPS) used for domestic water and irrigation applications in developing regions.
“No previous study has proposed such a method to assess borehole evolution over the lifetime of PVWPS,” lead author of the research, Simon Meunier, explained to pv magazine . “In particular, it leverages the system’s PV panels as a power source to perform periodic borehole pumping tests, rather than relying on diesel generators, and can be applied in a variety of contexts, benefiting communities, governments, NGOs, and other stakeholders dedicated to sustainable water and energy solutions.”
In the article “ Photovoltaic pumping tests : A novel supervision method for photovoltaic water pumping systems” published in Heliyon, Meunier and colleagues explain that the novel test method offers innovative and practical advantages such as continuous and cost-effective monitoring, reduced emissions and logistical complexities, as well as increased system longevity and groundwater sustainability.
“Conventional PVWPS borehole testing typically requires diesel generators and considerable manpower, making it expensive and often only feasible before the PVWPS is installed,” Meunier explained. “In contrast, our method allows for continuous monitoring of boreholes without additional fuel costs or water supply interruptions.”
They also stressed that many African countries now require pumping tests prior to the installation of a pumping system in the well or at the commissioning of the well, noting that these tests are usually carried out within a few days. In addition, some countries also require testing after installation to protect the wellbore over time.
"Most of the focus is on water contamination, with regulations on minimum distances between the borehole head and other facilities, on the borehole cap, on the slope of the hillside around the borehole head to prevent surface water from entering the borehole, and on the presence of waste near the borehole," the study notes.
According to its creators, the proposed methodology monitors the borehole water levels at different flow rates without interrupting the operation of the PVWPS. The test setup uses a “non-intrusive” flow sensor that can be uninstalled once the test is complete. It measures the hydrostatic pressure induced by the height of the water above it.
“The equipment is set up approximately 1 h before sunrise to be ready to start measurements when the water in the well is still at its static depth,” the scientists said, noting that the test could easily be carried out by a single technician. “Data collection starts 30 minutes before sunrise. Measurement is interrupted about 2-3 h after sunset, to collect data throughout the day and observe the recovery of the water level without pumping.”
According to Meunier, these tests allow problems such as well blockage to be detected in time. “Periodic monitoring using photovoltaic pumping tests promotes sustainable groundwater management, avoiding over-extraction and prolonging the operational life of both the borehole and the PVWPS,” he added.
The proposed methodology was tested on a 600 W PVWPS installed in 2018 in Gogma, Burkina Faso, where there is no centralised water supply network. The system supplies about 7 m3 of water per day for about 280 inhabitants. “The borehole is 56 m deep, with an internal diameter of 0.11 m and the motor pump is located at a depth of 30 m,” the scientists specified. “The height between ground level and the level at which the water enters the reservoir is 7.6 m.”
They found that the proposed test method accurately determines the drilling parameters, achieving a model fit with a mean coefficient of determination (R2) of 0.99. They also calculated that the cost of a PV pumping test was $43, compared to $511 for the multi-step depletion test and $2,050 for long-term tests.
“Furthermore, over a 10-year period (the estimated life of the pump), the cumulative cost of performing bi-annual PV pumping tests is less than 10% of the expense of replacing the pump prematurely,” they add. “Over a 50-year period (the estimated life of the well), the total cost of bi-annual PV pumping tests amounts to only 13% of the cost of drilling a new well.”
“By using solar energy instead of diesel, this method reduces emissions and logistical complexities, aligning with sustainability goals,” Munier concluded.
The research team included academics from the University Paris-Saclay in France, the Sorbonne University in France and the Institut Photovoltaique dÎle de France, as well as Stanford University in the United States and Imperial College London in the United Kingdom. |
