Controlled light-soaking experiment for amorphous silicon modules

Multijunction amorphous silicon (a-Si) solar cell modules from three manufacturers were subjected to light soaking at 1 sun intensity at 50°C for 2000 h, with annealing to 70°C in the dark after 1000 h. Characterization was done periodically, both under a Spire solar simulator and outdoors. Aperture area efficiencies as high as 7.2% were obtained after 1000 h of light soaking. The power output after 1000 h of light soaking subsequent partial annealing ranged from 78% to 92% of the initial power output. The recovery in power due to annealing was 2-4%. The performance is fitted with a stretched exponential curve obtained using the data obtained for the first 1000 h of light soaking. For two types of modules, stabilized performance was reached before 1000 h