**3. Spectral response of conventional and transparent PV cells**

The spectral response of conventional and transparent solar cells is shown in **Figure 3**. The absorptive response (black curve) is superimposed on the solar spectrum (gray curve). In the conventional cell, the wavelengths at which absorption is relatively high include the visible spectrum (400–700 nm). The transparent cell absorbs well in the near-infrared and the ultraviolet spectrum but the absorption drops off and approaches zero in visible range [22].

The current transparent solar cells transmit more than 70% of the visible light, which is within the range of tinted glass used in the windows of buildings with a

power-conversion efficiency of about 2%. Lunt and Bulović claimed that it can able to reach over 12% efficiency on basis of theory. Lunt already has demonstrated transparent cells integrated into series can power the liquid crystal display on a small clock, relying entirely on ambient light [23].
