Solar cells: Basics

Shah, A.V.; Shah, A.V

doi:10.1007/978-3-030-46487-5_3

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Solar cells: Basics

Shah, A.V.

Springer Series in Materials Science 301: 33-72

2020

ISSN/ISBN: 0933-033X

DOI: 10.1007/978-3-030-46487-5_3
Accession: 101151128

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Summary

The present chapter is a central chapter of this book. In this chapter, we will attempt to explain and illustrate the functioning of a solar cell. It is divided into six sections:Section 3.1 explains the interaction between Light and a Semiconductor, like silicon- which is the main material used in solar cells. This section involves physical concepts, which may possibly be new for the Reader, but should not be too difficult to understand. As a result of light being absorbed in the solar cell, electrons and "holes" (= "missing" electrons) are generated within the semiconductor.Section 3.2 is the "key section" of the present chapter. As most solar cells are constituted of semiconductor diodes, this section will introduce the mathematical description of a diode. The characteristics of such a device can, in general, be described by an exponential function- a fact that is well established, both theoretically and experimentally. The exponential function used to describe diodes (and solar cells), has two main parameters:The diode ideality factor n. Basically, n should be equal to 1, but for practical reasons n is usually higher than 1. The interpretation of this fact goes beyond the scope of the present book.The diode reverse saturation current density J0. This parameter should be as low as possible, to ensure a high performance of the diode and, thus, of the entire solar cell.Afterwards, we will introduce a light source. The diode becomes a photodiode or a solar cell. This is simply done by adding a photo-generation term to the diode equation, a procedure that is well established, but not easy to justify theoretically.Section 3.3 describes how the internal electric field present in all diodes is instrumental in separating electrons and "holes" and, thus, providing a current to the contacts of the solar cell.Section 3.4 deals with the electrical characteristics of the solar cell: Equivalent circuits and key parameters.Section 3.5 describes the limits for solar cell conversion efficiency, and, also, how these limits are affected by operating conditions: by temperature, and by the intensity of the incoming light.Section 3.6 introduces two important "tools", which are used to evaluate solar cells: the measurement of the cell's "Spectral Response" and of its "Quantum Efficiency". Section 3.6 will explain the difference between these two methods, as well as their practical use.

Solar cells: Basics

Shah, A.V.

Springer Series in Materials Science 301: 33-72

2020

Full-Text Article emailed within 0-6 h

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