Recently, we introduced a simple power law model (PLM) to represent the J-V characteristics of an illuminated solar cell with parasitic resistances. The model is useful for design, characterization, and parameter extraction of solar cells and modules. The form of this model was arrived at by intuition, and its applicability to a few moderate-quality cells with bias-independent photocurrent was demonstrated by curve fitting to theoretical and measured J-V data. In this paper, we present an analytical derivation of the closed-form PLM from a physics-based implicit J-V equation having a bias-dependent photocurrent and an exponential term. Apart from providing a theoretical basis for the hitherto empirical PLM, the derivation expands the scope of this model significantly to cover poor- to high-quality cells with different physical phenomena and provide new insights. © 2011 IEEE.

Shreepad Karmalkar

Department of Electrical Engineering

Analytical model

BIAS-DEPENDENT PHOTOCURRENTS

Closed form

CLOSED-FORM MODEL

High quality

Implicit model

J-V characteristics

Parasitic resistances

Physical phenomena

Physics-based

Power law

Power law model

THEORETICAL BASIS

V-MODEL

Computer simulation

Curve fitting

Mathematical models

Models

parameter extraction

Solar cells

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Analytical Derivation of the Closed-Form Power Law $J$ – $V$ Model of an Illuminated Solar Cell From the Physics Based Implicit Model

IEEE Transactions on Electron Devices

We have earlier introduced the power law equation, j=1-(1-γ)v- γvm, where j=J/Jsc and v=V/V∝, to simplify determination of the JV curve, fill-factor and peak power point of an illuminated solar cell from a few measurements as well as physical parameters. However, the validity of the various formulae and parameter extraction procedure was established for a limited class of cells, having moderately convex JV curves with fill-factors of 0.560.77 and obeying single exponential theory with bias independent photocurrent. This paper presents a thorough validation of the model proposed earlier. New formulae and parameter extraction procedure are presented to extend the applicability of the power law equation to a much wider variety of cells. The JV curves considered in this paper range from concave (fill-factor&lt;0.25) to highly convex (fill-factor&gt;0.85), and their theoretical expressions contain bias dependent photocurrent and double exponential terms. It is shown that the power law equation also simplifies the calculation of the cell bias point for an arbitrary load. © 2010 Elsevier B.V. All rights reserved.

Solar Energy Materials and Solar Cells

The power law J-V model of an illuminated solar cell

For a variety of solar cells, it is shown that the single exponential J-V model parameters, namely-ideality factor η, parasitic series resistance Rs, parasitic shunt resistance Rsh, dark current Jo, and photogenerated current Jph can be extracted simultaneously from just four simple measurements of the bias points corresponding to Voc ∼ 0.6 Voc, Jsc and ∼ 0.6 Jsc on the illuminated J-V curve, using closed-form expressions. The extraction method avoids the measurements of the peak power point and any dJ/dV (i.e., slope). The method is based on the power law J-V model proposed recently by us. © 2009 IEEE.

IEEE Electron Device Letters

An analytical method to extract the physical parameters of a solar cell from four points on the illuminated J-V curve

An accurate J-V equation of a practical solar cell is inherently implicit, which necessitates iterative calculations to determine the fill factor and the peak power point. We propose a simple explicit power-law J-V model that is applicable to a wide variety of solar cells. The model allows an easy prediction of the entire J-V curve, peak power point, and fill factor from four simple measurements of the bias points corresponding to Voc, ∼ 0.6 Voc, Jsc, and ∼0.6 Jsc, where Voc is the open-circuit voltage and Jsc is the short-circuit current density. The model also provides a closed-form description of the J-V curve, peak power point, and fill factor in terms of physical parameters of the single exponential model. © 2008 IEEE.

A physically based explicit J-V model of a solar cell for simple design calculations

Solar cells parameters evaluation considering the series and shunt resistance

Thin Solid Films

Results on monocrystalline CuInSe2 solar cells

Analytical derivation of the closed-form power law J-V model of an illuminated solar cell from the physics based implicit model

Journal	IEEE Transactions on Electron Devices
ISSN	00189383
Open Access	No