Evaporation ponds are shallow ponds that concentrate dissolved solids through evaporation. The use of evaporation ponds to obtain salt from sea water is one of the oldest applications of solar energy. Modern uses include concentrating brine solutions used in leach mining and removing dissolved solids from waste streams. Altogether, evaporation ponds represent one of the largest commercial applications of solar energy in use today.
Unglazed transpired collectors (UTC) are perforated sun-facing walls used for preheating ventilation air. UTCs can raise the incoming air temperature up to 22 Â°C and deliver outlet temperatures of 45-60 Â°C. The short payback period of transpired collectors (3 to 12 years) make them a more cost-effective alternative to glazed collection systems. As of 2009, over 1500 systems with a combined collector area of 300,000 mÂ² had been installed worldwide. Representatives include an 860 mÂ² collector in Costa Rica used for drying coffee beans and a 1300 mÂ² collector in Coimbatore, India used for drying marigolds.
A food processing facility in Modesto, California uses parabolic troughs to produce steam used in the manufacturing process. The 5,000 mÂ² collector area is expected to provide 4.3 GJ per year.