solar thermal panels
From solar panels on the roof, heat from the sun is captured and transferred to hot water tanks via a glycol heat exchange system, giving natural warmth to showers and faucets throughout the hostel.
how it works
Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to generate thermal energy or electrical energy for use in industry, and in the residential and commercial sectors. Systems for utilizing low-temperature solar thermal energy include means for heat collection; usually heat storage, either short-term or interseasonal; and distribution within a structure or a district heating network. In some cases more than one of these functions is inherent to a single feature of the system (e.g. some kinds of solar collectors also store heat).
Sources : Wikipedia, Theusgroup