Paleo-Dneister Holocene history: use of palynostratigraphy to assess the validity of dating by amino acid racemisation and C-14 ages of Black Sea shells

Abstract

The problems of worldwide energy shortage and environment pollution are becoming more and more serious, thus lots of attention has been paid to renewable and sustainable energy. The development of photovoltaic technology was rapid in recent years as one of the promising renewable energy, the worldwide total amount of photovoltaic power plants had reached nearly 100 GW in 2012, and about 90% of the worldwide solar cells are crystalline silicon solar cells. But there is still a large gap between the electricity costs of photovoltaic and traditional fossil energy, lots of methods have been tried to decrease the costs. The efficiency of the cell could be increased by concentration, and parts of the solar cells are replaced by cheaper optical elements in concentration photovoltaic, thus the costs of photovoltaic could be decreased by concentration. The traditional solar cells used for concentration were III–V multi-junction solar cells, their costs were high although they had high efficiency, thus people tried to use cheaper silicon solar cells for concentration to decrease the costs further. In this work, six kinds of silicon solar cells with different structures used for concentration were summarized; the device structures, manufacturing processes and efficiencies of the cells were compared. The prospects of concentrator silicon solar cells were predicted, the Si HIT cell using back contact structure, the multi-junction cell containing Si back contact cell and the Si VMJ cell used with Ge and GaP VMJ cells were considered to have good potential in low, middle, high and very high concentration photovoltaic.