The photo-to-electricity energy conversion efficiencies of ruthenium-dye-sensitized solar
cells (DSC) are measured under a solar simulator. The error in conversion efficiencies was
compared under a variety of spectral conditions. Measurements of the conversion efficiencies
of DSC between a solar simulator and outdoor sunlight result in about 10% error. This error
was seen when the spectral intensity of a xenon-lamp solar simulator (imitating an air mass
(AM) 1.5 spectrum) was adjusted by the short-circuit photocurrent ISi of a crystalline silicon
(c-Si) standard cell. In order to adjust the energetic intensity of AM 1.5 for DSC that has a
spectrum response only in the visible region light, the c-Si reference cell is modified with a glass
UV filter (KG-5, Schott) and the solar simulator was adjusted by IIR-cut Si. The energetic
spectrum of the solar simulator has a good accuracy over the wavelength range 300–750 nm,
giving the conversion efficiency of DSC an accuracy of about 2%. The dependency of the ratio
of ISi to IIR-cut Si on natural sun power is discussed in view of scattering of the visible light
under changing natural sun light.