ABSTRACT
Glossary absorber area the area of a solar thermal collector where radiation energy is converted into thermal energy absorption the incorporation of a substance in one phase state into another substance in a different phase state. This involves the whole volume of the liquid absorptivity the fraction of radiation absorbed at a specific wavelength adsorption the physical bonding of a gaseous or liquid substance onto the surface of another substance of a different phase. Extraction of the water is usually via boreholes chilled water, water used for process cooling or air-conditioning purposes. The net present value (NPV) is the present value of the difference between cash inflows and cash outflows, taking inflation and returns into account optical collector efficiency the maximum efficiency of a solar collector. The optical efficiency denotes the optical losses of a collector, consisting of refection and absorption in the glass cover as well as refection from the absorber sheet.
