Cell-to-Module Variation of Optical and Photovoltaic Properties for Monocrystalline Silicon Solar Cells with Different Texturing Approaches

Abstract

The power output and efficiency of solar cells are affected by the encapsulation, a fact that is often overlooked when the optical performance of different types of wafers is compared. In this work a full understanding of the impact of textured monocrystalline silicon wafers typically applied in the industry on the cell-to-module (CTM) variation of reflectivity, current–voltage (IV), and quantum efficiency (QE) characteristics, has been developed. Comparing to the acid and reactive ion etching (RIE), texturization of silicon surface with alkali (KOH) treatment was found to have significantly reduced reflection by 7.02%, enhanced short-circuit current (Isc) by 9.325 A, the maximum power (Pmax) by 4.770 W and external quantum efficiency (EQE) by 83.76%. The internal quantum efficiency (IQE) spectra indicates that recombination within the nanoporous surface from RIE texture evidently limits its blue IQE and then affects the Isc. After encapsulation, the CTM variation from reduced reflection and IQE results in a coupling effect of short circuit current gain. However, such current gain leads to a CTM power reduction due to the increased resistance (Rs) loss of I2Rs. Compared to alkali and RIE texturing, the acid texture approach can give the minimum CTM power loss, although obtained absolute power is the smallest. Further photoelectric conversion efficiency improvements are possible with better texturing structures, while the coupling CTM gain can be increased by optimizing encapsulation process.