A Cole

Laser Grooved Buried Contact Solar Cells for Concentration Factors up to 100x

The laser grooved buried contact (LGBG) crystalline silicon solar cell is an attractive technology for the production of low-cost concentrator cells. Due to the high-conductivity buried front contact, the metallization pattern may be readily adapted to handle the larger current densities produced at higher concentrations whilst minimizing shading. In the 1990s an efficiency of 18% at 30X concentration without prismatic covers was demonstrated in the EUCLIDES concentrator system. A matrix of cell process conditions has been investigated in order to optimize the emitter and front contact design of the LGBC cell for concentration factors of 50-100X. Efficiencies over 18% at 50X concentration have been measured on 2.56 cm2 cells. Factors limiting the efficiency are discussed and processing improvements are suggested

Silicon Based Photovoltaic Cells For Concentration–Research And Development Progress In Laser Grooved Buried Contact Cell Technology

The Laser grooved buried contact silicon solar cell (LGBC) process employed by Narec currently produces LGBC cells designed to operate at concentrations ranging from 1–100 suns and has demonstrated efficiencies at 50X of over 19% and at 100X of over 18.2% using 300 μm CZ silicon[1] wafers. As part of the LAB2LINE[1], APOLLON[2] and ASPIS[3] projects funded under the European Commission Framework Programs (FP6 and FP7) we have made improvements to the LGBC process to improve efficiency or make the cell technology more suitable for industrial CPV receiver manufacturing processes. We describe a process which hybridizes LGBC and more standard screen printing technologies which yields at least a 6% relative improvement at concentration when using more readily available 200 μm thick CZ wafers. We describe a pioneering front dicing technique (FDT). The FDT process is important in small cells where edge recombination effects are detrimental to the performance. We show that by using this new technique we can produ...

Process optimisation for coloured laser grooved buried contact solar cells

The use of photovoltaic modules in architectural applications is now firmly established and large modules of glass-glass construction produced specifically for the BIPV market are available. However, the range of solar cell colours and shapes currently offered by suppliers is still very limited and this is a barrier to the widespread use of PV modules as constructional components. Initial investigations of the colour and efficiency of Laser Grooved Buried Contact (LGBC) solar cells as a function of the thickness of the LPCVD silicon nitride antireflection coating were reported in the late 1990s, but the subsequent commercialisation of coloured cell products has been limited in part by the difficulty in controlling the uniformity and reproducibility of colour in large scale cell production. The aim of the present work is to understand and control the processes that affect the thickness and hence colour of the silicon nitride ARC. Process conditions were optimised to enable the formation of antireflection coatings with thicknesses in the range 90 nm to 400 nm. LGBC solar cells were fabricated in 5 colours on both non-textured Cz and partially textured multicrystalline wafers. Good uniformity of colour was achieved both across individual cells and throughout whole process runs. Laser scribing was used to produce cells in a range of shapes which, in conjunction with the choice of colours, demonstrates the potential for novel BIPV applications.