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SOLWA (SOLar WAter)
SOLWA in practice

Solar still is based on the conversion of the solar beams into heat. Inside an isolated structure (the greenhouse itself), solar beams radiate a salt water basin, heat up the solution and make it evaporate. The vapor condensates in the internal surface of the greenhouse and is collected, whilst the rich salt solution is eliminated. This is the basic principle of solar stills.

The SOLWA solar still forces the evaporation process even more and increases the drinkable water production, presenting two innovations that distinguish it from others currently in use: it does not need external maintenance, and it forces the evaporation of the solution at lower temperatures. A specifically designed software calculates the construction characteristics, based on the climatic conditions of the territory and of the solution to process through the solar still.

SOLWA is constructed from materials that are easily accessible in any country and territory, and it does not demand expert or qualified labor. Figure 2 illustrates the phases of construction of the SOLWA. The images show the simplicity of the construction and materials: common wooden pallets turned upside down, expanded polyurethane (a normal insulator for roofs) and Plexiglas. Other technical materials, such as small copper pumps or pipes, are also widely commercially available.

The employment of materials easily available and with contained costs allows the solar still to have a limited cost against its high social value, producing a necessary factor for life

Figure 2 Building steps of the solar still, employing economic and easily available materials

The electric power necessary in order to make the entire system work is produced through a small solar panel. Indeed, solar radiation is the only energy source of this system, which allows it to be completely independent and to operate in any conditions.

The creation of elevated temperature inside the structure and the simplicity of the mobile structures used, allow the solar still to have other possible functions. The SOLWA can indeed produce drinkable water also from waters polluted by chemical or biological agents. The foreseen feasibility to decide the time of permanence of the solution inside the structure helps calibrate the inner temperature and helps deploying the solar still as a proper distillery for various uses. It can be used for drying sludge or waste of various nature, reducing the volume to eliminate.