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energetica-india-57_asiapowerweek

Illustration 2: Mono/Bifacial Modules : A bifacial module offers greater flexibility in terms of positioning, regional problems such as pollution can be significantly reduced. ple, provided they do not recombine at the dangling bonds.The wafer material (e.g. silicon) basicallydetermines the maximum efficiency.The idealwafer thickness results from the optimum combination of light absorption and the lifetime of the charge carriers in and on the wafer. If we now look for the “best” concept, we come up essentially with two systems: 1. IBC cells:The light can enter on the entire surface of the cell;all the metallization is on the rear.These cells currently rank among the most efficient mass-produced solar cells and achieve 25%.The production costs are, however, very high and despite many years of optimization, companies such as Sunpower are also seeking to open up mainstream markets without excessive premium surcharges. 2. Bifacial cells:With bifacial cells, the light-sensitive surface area is doubled, without the need for more wafer material or module area. The bifaciality of current cells is better than 85%, often even better than 92% (remark- bifaciality factor of PERC cells typically below 50%).A module of this type can generate 10 to 30% more energy than a mono facial module, at minimum or even no cost.As a result, the Wp_AC of PV systems is automatically reduced by typical 15% for Heterojunction systems . The cell concept suits the optimum cell remarkably well; bifacial cells have an almost symmetrical construction and the heterojunction concept, in particular, enables double-sided passivation of wafer surfaces, which increases efficiency considerably. HJT-Si cells of this type currently hold the record for simple pn cells, set by Panasonic with 25.6% on 98μm thick wafers. Good passivation is responsible for a high cell voltage and for physical reasons, this means a good temperature coefficient, i.e. the efficiency is maintained even in hot climates.Up to now, HJT cells have been developed on machines used for the production of semiconductors. Using the HELiA, mass production of HJT cells with very high passivation has been achieved, as the MAiA already successfully demonstrates with the PERC cells. We are convinced that both PV routes can be pursued further, whereas the end of the pure cost reduction route will soon be reached. Future cost reductions will only be possible with better overall solutions. Graph 2: Module Efficiency in relation to Surface Area. SOLAR POWER 28 energetica INDIA · MAY | JUN16


energetica-india-57_asiapowerweek
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