It is an important source of renewable energy<span> and its technologies are broadly characterized as either </span>passive solar<span> or </span>active solar<span> depending on how they capture and distribute solar energy or convert it into </span>solar power<span>. Active solar techniques include the use of </span>photovoltaic systems<span>, </span>concentrated solar power<span> and </span>solar water heating<span> to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable </span>thermal mass<span> or light-dispersing properties, and designing spaces that </span>naturally circulate air<span>.</span>
