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Analyzing back contacts of silicon solar cells by Suns-VOC-measurement at high illumination densities

 
: Glunz, S.W.; Nekarda, J.; Mäckel, H.; Cuevas, A.

:
Fulltext urn:nbn:de:0011-n-734673 (296 KByte PDF)
MD5 Fingerprint: c9003787cf12a82155a92ad17a311a52
Created on: 21.9.2012


European Commission, Joint Research Centre -JRC-:
The compiled state-of-the-art of PV solar technology and deployment. 22nd European Photovoltaic Solar Energy Conference, EU PVSEC 2007. Proceedings of the international conference. CD-ROM : Held in Milan, Italy, 3 - 7 September 2007
München: WIP-Renewable Energies, 2007
ISBN: 3-936338-22-1
pp.849-853
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <22, 2007, Milano>
English
Conference Paper, Electronic Publication
Fraunhofer ISE ()

Abstract
This work demonstrates the feasibility and usefulness of a new method to analyse the quality of the rear contact of silicon solar cells separated from other ohmic loss channels as e.g. the resistive loss in the front contact grid. The measurement is based on SunsVoc data at high illumination densities between 1 and 1000 suns. Generally the rear contacts can be described as a Schottky diode with a shunt resistor in parallel. At 1 sun operation conditions the back contact is fully dominated by the shunt showing an ohmic behaviour. However, at high illumination densities the Schottky diode can not be shunted completely anymore resulting in an increasing voltage which is opposed to the pn junction voltage. Finally a reversal point in the SunsVoc characteristics can be observed, i.e. the voltage decreases with increasing illumination density. The evaluation of this characteristic behaviour is used to extract physical parameters like the barrier height of the contact. Additionally the contact quality is assessed for different contact types and base doping concentrations. The predicted contact quality is in good correlation with the measured fill factors of the cells.

: http://publica.fraunhofer.de/documents/N-73467.html