B. Moralejo

Trends in crystalline silicon growth for low cost and efficient photovoltaic cells

Photovoltaic (PV) industry is facing one of its worst times ever. The over-capacity and the reduced market worldwide are impacting the supply/demand across the PV value chain, leading to certainly low sell prices, noticeably below the production costs. As a consequence, many factories are going into insolvency in these times. In addition, the insufficient options to install PV modules demand devices based on well-optimized cost/performance (CP) ratios. Crystalline growth of silicon solar wafers for PV silicon devices has a direct influence on this critical relation. Two industrial approaches aiming at improving the CP ratio will be presented in this paper: i) the use of high-grade umg-Si feedstock and ii) the implementation of new seed-growth monocast process.

Low-cost system for full-wafer photoluminescence characterization of photovoltaic silicon

Photoluminescence imaging technique has recently emerged as a powerful tool for obtaining very quick sorting of silicon based solar wafers and cells. In this work, we report on a low-cost photoluminescence imaging system, paying special attention to the different constituting elements. Results on both commercial multicrystalline (mc) and seed-monocast (sm) Si wafers and solar cells are discussed.

Trapping activity on multicrystalline Si wafers studied by combining fast PL imaging and high resolved electrical techniques

Multi-crystalline Si is the preferred material in the photovoltaic world market due to the good balance between production costs and efficiency. However, it has a large number of defects acting as recombination centers for the photogenerated carriers. In this work, we use both the fast inspection provided by the photoluminescence imaging technique with the very high spatial resolution of the light beam induced current and electron beam induced current techniques, for obtaining a comprehensive understanding of the electrical activity and distribution of defects in this material.

Combined EL and LBIC Study of the Electrical Activity of Defects in Solar Cells Based on Innovative Wafers Grown by Casting Methods

In this paper we combine LBIC and EL measurements of commercially multi-crystalline silicon solar cells, in order to obtain detailed information about the electrical activity around defect areas. This integrated analysis is suitable for the study of different crystal defects at both micrometric and full wafer scale. In particular, the electrical activity of some defect areas is studied in detail by means of highly spatially-resolved LBIC maps, showing important differences in their behaviours. A discussion about the origin of these differences is presented.