Learning from success : photovoltaic-powered water pumping in Mali

This study documents the experience with photovoltaic (PV) water pumping in Mali since 1977, and includes information on system operations and maintenance, economics and social considerations. In 1989 there were 157 PV pumping systems in Mali, with a cumulative capacity of 220 kW. The PV systems had the following characteristics: average power rating 1500 W; nearly all powered by single- or poly-crystalline silicon; pumping head mostly 30-40 m; main types submerged motor/submerged pump and surface motor/submerged pump (the latter was being discontinued due to high failure rates); installation costs US$ 8-16 per peak watt. Monitoring of 66 pumps from 1983 to mid-1989 found 37 failures which meant that the average pump availability was more than 99%. The success of Mali PV pumps was principally due to user education, and a good network of maintenance and spare parts delivery. Although PV systems still required donor financing, there was a trend towards increased contributions from beneficiaries. A cost analysis revealed that PV systems had comparable or lower costs than hand, camel or diesel pumping, for water table depths greater than 15 metres and for villages of over 250 people. On an intial cost basis, PV systems are US$ 35-60/person compared to US$ 27-136/person for handpumps, depending on water table depth.