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Located in the heart of sub-Saharan Africa, between latitudes 10 ยฐ and 25ยฐN, Mali has a land area of 1.204 million km 2. The population is presently estimated to be 12 million with a per capita energy consumption or 227 ktoe per inhabitant per year. Wood fuel still represents 90% of the total energy consumed. Mali does not have any economically exploitable petroleum deposits, but it receives an average solar insolation of 6.3 kW h/m2/day. The review of the potential and problems of solar photovoltaic (PV) technology in Mali shows that high ambient temperatures affecting the performance of PV systems, high cost of installed PV systems, poor after-sale service and passive participation of local communities in implementation of the programmes remain the main constraints and challenges. It is recommended that given Mali's meagre conventional energy resources, research should be intensified on low cost technology that minimizes the effect of high temperatures on the performance of PV systems. Efforts should be made to avoid duplication of unsuccessful experiences, improve coordination of activities in this area and promote private sector participation.
02/02550 Spectral effects on amorphous silicon solar module fill factors Riither, R. et al. Solar Energy Materials & Solar Cells, 2002, 71, (3), 375-385. The outdoor operation and monitoring of amorphous silicon (a-Si) solar modules present unique features when compared to the more traditional and quite well-understood operation of the crystalline silicon (c-Si) technology. The peculiarities of a-Si contrast to such an extent with those of c-Si solar cells that in the field, while the former performs better during summer, the latter is more efficient in winter. Concepts usually applied to describe phenomena in c-Si devices are often inadequate to describe the performance of a-Si cells. When looking at module performance, the fill factor (FF) can be regarded as one of the characteristic photovoltaic quantities of major interest. Under outdoor illumination, cells are seasonally exposed to different solar spectral contents and intensities, which vary considerably from summer to winter. The FF depends on both the quality (spectrum) and quantity (irradiation) of the incident light. In this context, results are reported showing spectral effects on the FF of amorphous silicon solar modules deployed outdoors. While "blue" spectra improved the FF of a-Si devices, the contrary was observed for "red" spectra. The voltagedependent spectral response of a-Si devices is also described and quantified. Our results reveal that a-Si modules can perform quite well at low irradiations and mainly diffuse spectra. Thus, it is concluded that in system sizing programmes, the performance of a-Si modules should be treated more precisely with respect to spectra, to reveal their true operational characteristics and advantages.
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