"Thin film’s technical constraints — in particular, conversion efficiency rates that are generally lower than crystalline-silicon panels — are a big reason for the low market share. Take amorphous silicon, or a-si, as it’s known in the industry. * * * a-si makes up the majority of Hanergy’s production capacity today. But Hanergy’s panels had conversion efficiency rates well below 10%, according to two former employees, compared with the industry average of about 15%.
"Moreover, Hanergy’s a-si panels are susceptible to degradation–basically meaning a decline in the amount of power the panels can put out. The former employees said Hanergy’s a-si panels degraded at double-digit rates in the first two years of operation, compared with less than 1% for crystalline silicon panels.
"Hanergy widened its options through the purchase of overseas companies developing other types of thin-film technology. The company acquired Germany-based Solibro GmbH in 2012. * * * With the overseas acquisitions, Hanergy expanded its thin-film portfolio to include technology known as CIGS — short for copper indium gallium selenium. CIGS is viewed as promising technology in the industry, with the highest efficiencies among all thin-film technologies, according to CLSA analyst Charles Yonts. Solibro says the company’s thin-film modules can offer efficiencies higher than 13%. * * * [However] CIGS can suffer stability issues in hot or humid environments, according to CLSA.
(b) The a-Si (used in thin film solar cell) is distinct from traditional crystalline silicon (c-Si). The latter encompasses
(i) multicrystalline silicon (multi-Si; also known as polycrystalline silicon; with the characteristic blue color we often see) and
(ii) monocrystalline silicon (mono-Si).
(c) Founded in 2009 and based in Taichung, TSMC Solar--still in research phase (ie, not commercializing yet) on Apr 29, 2015 set CIGS 16.5% efficiency (world) record, improving on its previous record of 15.7% set in 2013.