Model pv

2DO CONGRESO IBEROAMERICANO DE ESTUDIANTES DE INGENIERÍA ELÉCTRICA, ELECTRÓNICA Y COMPUTACIÓN (II CIBELEC 2005)

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Model of Photovoltaic Module in Matlab™
Francisco M. González-Longatt

Abstract— This paper define a circuit-based simulation model for a PV cell in order to allow estimate the electrical behavior of the cell with respect changes on environmental parameter of temperature andirradiance. An accurate PV module electrical model is presented based on the Shockley diode equation. The general model was implemented on Matlab scrip file, and accepts irradiance and temperature as variable parameters and outputs the I-V characteristic. A particular typical 60W solar panel was used for model evaluation, and results was compare with points taken directly from the manufacturer’spublished curves and show excellent correspondence to the model. Index terms— Modeling photovoltaic module. and behavior, photocurrent,

II. PV GENERATOR A photovoltaic PV generator is the whole assembly of solar cells, connections, protective parts, supports etc. In the present modeling, the focus is only on cell/module/array [3]. Solar cells consist of a p-n junction fabricated in a thin waferor layer of semiconductor (usually silicon). In the dark, the I-V output characteristic of a solar cell has an exponential characteristic similar to that of a diode [4]. When solar energy (photons) hits the solar cell, with energy greater than band gap energy of the semiconductor, electrons are knocked loose from the atoms in the material, creating electron-hole pairs [5]. These carriers are sweptapart under the influence of the internal electric fields of the p-n junction and create a current proportional to the incident radiation. When the cell is short circuited, this current flows in the external circuit; when open circuited, this current is shunted internally by the intrinsic p-n junction diode. The characteristics of this diode therefore set the open circuit voltage characteristicsof the cell [4]. A. Modeling the Solar Cell Thus the simplest equivalent circuit of a solar cell is a current source in parallel with a diode. The output of the current source is directly proportional to the light falling on the cell (photocurrent Iph). During darkness, the solar cell is not an active device; it works as a diode, i.e. a p-n junction. It produces neither a current nor a voltage.However, if it is connected to an external supply (large voltage) it generates a current ID, called diode (D) current or dark current. The diode determines the I-V characteristics of the cell.

I. INTRODUCTION Renewable energy resources will be an increasingly important part of power generation in the new millennium. Besides assisting in the reduction of the emission of greenhouse gases, they addthe much- needed flexibility to the energy resource mix by decreasing the dependence on fossil fuels [1]. In other hand, deregulation of the electric utility industry is providing an opportunity for higher penetration and use of distributed resources (DR). Distributed resources are generation sources that can be located at or near loads. Distributed resources can provide benefits that bulk powergeneration can not. PV systems are ideally suited for distributed resource applications. Photovoltaic (PV) systems produce DC electricity when sunlight shines on the PV array, without any emissions. The DC power is converted to AC power with an inverter and can be used to power local loads or fed back to the utility [2]. The PV application can be grouped depending the scheme of interaction withutility grid: grid connected, stand alone, and hybrid. PV systems consist of a PV generator (cell, module, array), energy storage devices (such as batteries), AC and DC consumers and elements for power conditioning. This article refers about a model for modeling and simulation of PV module based on Shockley diode equation.

Fig. 1. Circuit diagram of the PV model

F.G.L. is in Universidad...