TY - JOUR

T1 - Impact of the contacting scheme on I-V measurements of metallization-free silicon heterojunction solar cells

AU - Brinkmann, Malte

AU - Haase, Felix

AU - Bothe, Karsten

AU - Bittkau, Karsten

AU - Lambertz, Andreas

AU - Duan, Weiyuan

AU - Ding, Kaining

AU - Sperlich, Hans Peter

AU - Waltinger, Andreas

AU - Schulte-Huxel, Henning

N1 - Funding Information: This work was financially supported by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) under contact number 03EE1080C (TOP). The authors thank J. Hensen, M. Wolf and D. Sylla (all ISFH) for their contribution to the measurements of the metallization-free solar cells.

PY - 2023/4/26

Y1 - 2023/4/26

N2 - I-V measurements are sensitive to the number and positioning of current and voltage sensing contacts. For busbarless solar cells, measurement setups have been developed using current collection wires and separate voltage sense contacts. Placing the latter at a defined position enables a grid resistance neglecting measurement and thus I-V characteristics independent from the contacting system. This technique has been developed for solar cells having a finger grid and good conductivity in the direction of the fingers. The optimal position of the sense contact in case of finger-free silicon heterojunction solar cells has not yet been studied. Here, the lateral charge carrier transport occurs in a transparent conductive oxide layer resulting in a higher lateral resistance. We perform finite difference method simulations of HJT solar cells without front metallization to investigate the impact of high lateral resistances on the I-V measurement of solar cells. We show the high sensitivity on the number of used wires for contacting as well as the position of the sense contact for the voltage measurement. Using the simulations, we are able to explain the high difference of up to 7.5% in fill factor measurements of metal free solar cells with varying TCO sheet resistances between two measurement systems using different contacting setups. We propose a method to compensate for the contacting system to achieve a grid-resistance neglecting measurement with both systems allowing a reduction of the FF difference to below 1.5%.

AB - I-V measurements are sensitive to the number and positioning of current and voltage sensing contacts. For busbarless solar cells, measurement setups have been developed using current collection wires and separate voltage sense contacts. Placing the latter at a defined position enables a grid resistance neglecting measurement and thus I-V characteristics independent from the contacting system. This technique has been developed for solar cells having a finger grid and good conductivity in the direction of the fingers. The optimal position of the sense contact in case of finger-free silicon heterojunction solar cells has not yet been studied. Here, the lateral charge carrier transport occurs in a transparent conductive oxide layer resulting in a higher lateral resistance. We perform finite difference method simulations of HJT solar cells without front metallization to investigate the impact of high lateral resistances on the I-V measurement of solar cells. We show the high sensitivity on the number of used wires for contacting as well as the position of the sense contact for the voltage measurement. Using the simulations, we are able to explain the high difference of up to 7.5% in fill factor measurements of metal free solar cells with varying TCO sheet resistances between two measurement systems using different contacting setups. We propose a method to compensate for the contacting system to achieve a grid-resistance neglecting measurement with both systems allowing a reduction of the FF difference to below 1.5%.

KW - Contacting

KW - Fill factor

KW - Heterojunction solar cell

KW - I-V measurement

KW - Metal-grid free

KW - Module integration

UR - http://www.scopus.com/inward/record.url?scp=85156190850&partnerID=8YFLogxK

U2 - 10.1051/epjpv/2023009

DO - 10.1051/epjpv/2023009

M3 - Article

AN - SCOPUS:85156190850

VL - 14

JO - EPJ Photovoltaics

JF - EPJ Photovoltaics

IS - 18

M1 - 18

ER -