S.E. Lyshevski, R.M. Reis
Rochester Institute of Technology, United States
pp. 27 - 30
Keywords: solar cell, crystalline silicon, analysis, modeling, experiments
In biomedical devices, cell phones, computer and tablets, consumer electronics, communication, security and even micro air vehicles, energy harvesting, energy storage and energy management are of a significant importance. In many applications, solar cells and photovoltaic modules guarantee autonomy, sustainability, overall energy requirements adequateness. For different applications, single- and muti-junction solar cells are fabricated using crystalline and monocrystalline silicon, amorphous and nanocrystalline silicon, cadmium telluride, copper indium gallium selenide, gallium arsenide and other materials. Quantum dots (CdS, CdSe, PbS, Sb2S and others), organic and polymer solar cells are used in some specialized applications. We examine commercial crystalline silicon solar cells which ensure cost-effectiveness, sufficient cell power density (~60 W/m3 for mono-Si and ~200 W/m3 for multi-Si), adequate efficiency (~15%), stability and robustness. We examine the application of the solar cell for the commercial and industrial generation systems (PGS) as well as for self-sustained biomedical, electronic and MEMS devices. The top n- and bottom p-type phosphorus and boron doped layers are forming the pn junction with a strong electrical field across. When photons are absorbed, the photocurrent is generated due to a flow of electrons. The solar cells and modules can be packaged using waterproof and transparent material. The output voltage of an individual c-Si cell usually is ~0. 5 V. The omages of the examined solar cells are reported in Figure 1. In solar cells, the absorption of photons results in generation of the charge carriers (electrons), and, subsequent separation of the photo-generated charge carriers. In crystalline silicon (c-Si) solar cells, there are two doped top n+ and back p+ layers. The performance of solar cell depends on: (1) Concentrations ND and NA of doping atoms which determine the width of a p-n junction space-charge region (donor atoms donate free electrons, while acceptor atoms accept electrons); (2) Mobility µ of electrons µn and holes µp, and, diffusion coefficient D which characterize the charge carriers transport due to drift and diffusion; (3) Lifetime τ and diffusion length L of the excess carriers which characterize recombination-generation; (4) Band gap energy Eg, absorption coefficient and refractive index R which characterize photon absorption. We are using a descriptive and physics-consistent model of solar cells as documented in Figure 2. The solar cells are characterized and tested. Using the experimental I–V, P–V and other characteristics, reported in Figure 3, the solar cell parameters are determined and identified. The software modeling, simulation and parameter evaluation tools are developed and substantiated. The experimental and calculated I–V and P–V characteristics are identical. The I–V and P–V characteristics are derived for different irradiation and temperature in the full operating envelope. This paper reports consistent analysis, modeling, simulation and software developments which can be applied to design of commercial/industrial PGS and self-sustained autonomous systems.