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31st European Photovoltaic Solar Energy Conference and Exhibition; 1984-1988, The Laboratory of Solar Energy and Energy Saving located in a hot climate area and the Laboratory of Photovoltaic Modules in a temperate climate zone, lead a common research program on the behavior of PV modules and the energy production according to the climate. For these purposes, the same outdoor characterization facilities have been mounted in the two laboratories. Then, the same silicon modules of different technologies have been installed on both platforms where the I-V curves as well as climatic parameters are continuously measured. Furthermore, electrical models are developed to analyze the data and each technology performance according to the environmental conditions. In the end, we expect that this facility helps us, on one hand to model the behavior of a given technology in a zone where a characterization tool is not available, and on other hand to choose the suitable technology for a given climate. For example, our first results show that the HIT modules give the highest yields in Burkina Faso, a hot environment.

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2455-2458, A study of the fabrication of thin-film silicon solar cells in the p-i-n superstrate diode configuration on plastic substrates at a temperature of 150 ºC, using different absorbing i-layers, is presented. A typical solar cell structure in this work comprises the following successive layers: PEN/GZO/p/buffer/i/n/metal. GZO is a transparent conductive window layer made of Zinc Oxide doped with Gallium and buffer is a high-bandgap ~10 nm-thick amorphous silicon layer. Flexible solar cells deposited entirely by radio-frequency plasma enhanced chemical vapour deposition on PEN had a conversion efficiency of 5.0%, JSC = 11.2 mA/cm2, and VOC = 0.830 V. Similar solar cells on PEN but with the i-layer deposited by hot-wire chemical vapor deposition had efficiency 4.53%, JSC = 12.7 mA/cm2, and VOC = 0.699 V. Based on the spectral response of the solar cells and on their I-V characteristics under different light levels, it is concluded that the efficiency of the devices is limited by recombination in the i-layer and by losses in the long wavelength part of the spectrum. Devices fabricated on PEN and on Asahi-U glass have comparable characteristics. However, the best fill factor obtained on PEN is 55.6% whereas on glass it is 60.1%. Nanocrystalline solar cells on PEN have high JSC (17.2 mA/cm2) but very poor FF (32.7%).

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2339-2342, We present results on the application of hydrogenated polymorphous silicon (pm-Si:H) grown at a variety of growth rates (1.5 - 9Å/s) in a standard 13.56MHz RF-PECVD system as the i-layer in 100mm x 100mm photovoltaic modules. We correlate the module characteristics with previously presented pm-Si:H material results. Material deposited at the highest growth rate (9Å/s) shows a low, mid-gap defect density of states - as determined by the modulated photocurrent (MPC) technique and the constant photocurrent method - and a hole diffusion length near 200nm in the light soaked state. Photovoltaic modules using this material as the absorbing i-layer were fabricated in superstrate p-i-n configuration. Initial active area efficiencies of 8.8% and 9.1% under AM1.5 have been achieved for modules with i-layers grown at 1.5Å/s and 9 Å/s, respectively, decreasing to 7.4% and 7.2% after light soaking. Values of VOC above 0.9V have been achieved using a p-type a-SiC:H layer and a-SiC:H buffer layers. After light soaking, modules grown at 1.5 Å/s and 5Å/s exhibit a decrease in fill factor of about 10%, but this is partially offset by an increase in VOC of 3-5%. However, for the modules with i-layers grown at 9Å/s, only a very small increase (~1%) in VOC is occasionally observed.