Sollektor – A New Approach to an Old Idea
Abstract
Even in "sunny" countries, despite the fact that an excess supply of sunlight outside, even during the daytime, windows are darkened and shut because of heat. Thus artificial light is used indoors requiring a high amount of energy. Moreover, these artificial lights are used at a very low level of efficiency only. If windows were left open, too much heat would penetrate through the windows. Thus in buildings, currently, most energy used is for air conditioning! The efficiency of the usual way of transforming solar energy to electricity and then back to light is typically less than 1% (Fig.1), and is always linked with production of unwanted heat, whereas an efficiency of up to 50% depending on the length is achievable by direct use of sunlight e.g. with the Sollektor approach (Poisel et al.).