Publication detail

The Temperature Dependant Efficiency of Photovoltaic Modules - a long term evaluation of experimental measurements

MACHÁČEK, J. DRÁPELA, J. PROCHÁZKA, Z.

Original Title

The Temperature Dependant Efficiency of Photovoltaic Modules - a long term evaluation of experimental measurements

Type

book chapter

Language

English

Original Abstract

The problematic can be put in short as follows. The photovoltaic cell is in essence a large-surface semiconductor diode working in the generator mode. Its volt-ampere characteristic has limit quantities, which give the magnitude of open-circuit voltage and the value of short-circuit current. These quantities vary in dependence on the change in solar intensity and in cell temperature. Multiplying the instantaneous values of voltage by the instantaneous values of current we obtain the power characteristic. The highest point of this characteristic represents the maximum value of potential power that the photovoltaic cell can supply to the load under given operating conditions. If we want to obtain this maximum power, the voltage across the electrical appliance must equal exactly the optimum voltage. With prolonged solar intensity or impaired cell-cooling conditions the cell surface temperature increases to as much as 60 C. With such elevated temperatures there is a change in the electrical properties of the cell that leads to reducing the load characteristic towards a lower voltage. A drop in the optimum voltage will reduce the power supplied to the accumulator. Since this phenomenon appears just with the highest solar intensity, we may lose a significant part of the obtainable daily generation by the photovoltaic cell (in dependence on the degree to which the accumulator is charged). To compensate for this phenomenon, an optimization facility can be used, which operates on the principle of increasing DC/DC converter. The essence of the solution consists in electronic power control of the loading of photovoltaic generators with respect to their instantaneous operating conditions. We constructed special long term measuring system for research this effect. Thanks to the system of collecting, archiving, and analyzing the data measured we can monitor, define, and subsequently interpret all positive and more significantly the negative external effects on the efficiency of the device. Demonstration and analyze measured data will be describe and discussed in article.

Keywords

soral cell, temperatuce, efficiency, photovoltaic.

Authors

MACHÁČEK, J.; DRÁPELA, J.; PROCHÁZKA, Z.

RIV year

2010

Released

1. 1. 2010

Publisher

In-Tech, Olajnica 19/3, 32000 Vukovar, Croatia

Location

Printed in India

ISBN

978-953-7619-52-7

Book

Renewable Energy

Edition

T J Hammons

Edition number

1

Pages from

415

Pages to

446

Pages count

32

URL

http://www.intechweb.org

BibTex

@inbook{BUT55186,
  author="Jan {Macháček} and Jiří {Drápela} and Zdeněk {Procházka}",
  title="The Temperature Dependant Efficiency of Photovoltaic Modules - a long term evaluation of experimental measurements",
  booktitle="Renewable Energy",
  year="2010",
  publisher="In-Tech, Olajnica 19/3, 32000 Vukovar, Croatia",
  address="Printed in India",
  series="T J Hammons",
  edition="1",
  pages="415--446",
  isbn="978-953-7619-52-7",
  url="http://www.intechweb.org"
}