The conversion efficiency of a crystalline silicon photovoltaic (PV) module increases as its temperature decreases. Considering this characteristic of the PV technology, in this study the authors analyse the use of cooled floating PV modules in a fraction of the area occupied by three reservoirs – Castanhão, Orós and Banabuiú – in the Brazilian semi‐arid region. Comparing with conventional ground‐mounted PV modules, an average conversion efficiency increase of 12.5% was measured for floating PV modules under the local weather conditions. In a second phase, measurements are used as input data in the PVSYST software in conjunction with a spreadsheet for the construction of electricity production scenarios. According to these scenarios, the potential PV production in the mentioned reservoirs would supply 7.4 and 18.8% of the electricity demand of Brazil's Ceará state (8.84 million inhabitants) and its largest city Fortaleza (2.6 million inhabitants), respectively.

This article describes a system that combines the technologies of reverse osmosis and photovoltaics to realize a pioneer project for drinking water supply to a rural community in semi‐arid Brazil (latitude 3°44′S), with a local yearly average temperature of 28°C and a yearly solar potential of about 2000 kW h m⁻². Two strategies are investigated: first the PV‐RO (photovoltaic powered reverse osmosis) plant is equipped with a DC motor; and second, a three‐phase induction motor is used. Through the analysis of the stored data the second option is chosen as the better alternative. This strategy has a specific electrical consumption (energy required to produce 1 m³ drinking water) of 3·03 kW h m⁻³, a recovery ratio of 27% (relation between drinking water product flow and brackish water input flow) and a drinking water cost of US$ 12·76 per m³. Copyright © 2004 John Wiley & Sons, Ltd.