Field test and analysis: the behavior of 3-J concentrator cells under the control of cell temperature

The behavior of triple junction concentrator cell (InGaP/(In)GaAs/Ge) under the control of cell temperature is investigated and evaluated at Toyota Technological Institute of Japan. The aim of this study is to investigate an accurate temperature coefficient as comparing the outdoor test with the theoretical calculation as a function of a sunlight concentration. Recently, the field test consisted of a total of 6 modules at two sites (Inuyama, Toyohashi) of Japan shows the peak efficiency of 26.8%±1.5%, and the triple junction cell shows the efficiency of 38.9% at 489 suns. In this study, a new dome-typed Fresnel lens (550×) that has the optical efficiency of 85.8% was used. The homogenizer is placed on the holder designed to control the cell temperature, and the outdoor test using the solar tracker was carried out under the 400×, 550× lenses. The conversion efficiency increases with the direct solar radiation, and decreases as increasing the receiver temperature. However, no change in I_SC was observed, and V_OC decreased slightly as a function of the receiver temperatures. The temperature coefficient obtained from the receiver at TTI shows the similar trends with them from the bare cell at Nara-AIST.