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Recently, very high conversion efficiencies in thin film polycrystalline solar cells have been reported. In particular it was reached an efficiency record both for CuInGaSe 2 (CIGS) and CdTe that are 19.2% and 16.5% respectively. We will briefly describe the technological methods used to fabricate these thin film solar cells. Besides, we will try to explain the reason why thin film polycrystalline devices can achieve conversion efficiency comparable with those shown by single crystal solar cells (mono-Si or poly-Si). We will take into consideration the tricks present in both the methods that allow to make the CIGS/CdS and CdTe/CdS thin film solar cells with excellent performances. We will show also, that these technologies are ripe for an "inline" industrial production and this makes thin film solar cells the best candidates for the large scale utilisation of photovoltaic energy conversion.

The state of the art of the second-generation of solar cells based on the CdTe and CuInGaSe 2 thin film technology will be described. This type of cells reached, on laboratory scale, photovoltaic conversion efficiencies respectively of 16.5% and 20.3% very close to those obtained with bulk materials. In particular, the materials, the layer sequences and deposition techniques used for the preparation of these two absorbers are described. Particular emphasis will be placed on major innovations that have enabled us to achieve high efficiencies with polycrystalline materials, showing how thin-film technology is mature enough to be transferred to industrial production. Finally, we will discuss about a project of technology-transfer developed at Parma University for the production of photovoltaic modules at an industrial level. In the near future, with our process, Arendi S.p.A. will reach a productivity of 18 MW/year.