In situ monitoring of electrical parameters of PV modules under mechanical stress

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Submitted on 9 Sep 2021

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In situ monitoring of electrical parameters of PV modules under mechanical stress

Julien Gaume, Jean-Patrice Rakotoniaina, Tatiana Duigou, Tristan Stevens

To cite this version:

Julien Gaume, Jean-Patrice Rakotoniaina, Tatiana Duigou, Tristan Stevens. In situ monitoring of electrical parameters of PV modules under mechanical stress. 38th EU PVSEC, Sep 2021, Lisbon, Portugal. 2021. �hal-03339851�

Commissariat à l’énergie atomique et aux énergies alternatives 150 avenue du lac Léman | 73375 Le Bourget-du-Lac

www-liten.cea.fr

CONTACT :

Tatiana DUIGOU

[email protected]

IN SITU MONITORING OF ELECTRICAL PARAMETERS OF PV MODULES UNDER MECHANICAL STRESS

PROTOCOL OF EXTRACTION OF LOCAL ELECTRICAL PARAMETERS CONTEXT AND AIMS OF THE STUDY

• The global electrical parameters of a module under mechanical stress, measured by dark I-V (DIV), vary.  Research into the local electrical behaviour of the module is of interest. Electroluminescence (EL), lock-in thermography (LIT) and light I-V (flash test / STC LIV) measurements can be used to have a deeper understanding of local electrical phenomena.

• Aims of the study:

 Adaptation of a protocol for extracting local electrical parameters;

 Extraction of the local electrical parameters of a mechanically loaded photovoltaic module.

Tatiana DUIGOU

, Tristan STEVENS

, Jean-Patrice RAKOTONIAINA

Julien GAUME

1

Univ. Grenoble Alpes, CEA, LITEN, DTS, SMSP, LAM

2

Univ. Grenoble Alpes, CEA, LITEN, DTS, SMSP, LSA

CONCLUSION PERSPECTIVES

• Improvement and use of a method for the electrical analysis of a module at local level

• Enables the physical cause of a fault to be determined: electrical or not? And if electrical, caused by diffusion, recombination, shunt, series resistance?

𝐽 = ^𝑝

𝑉_𝐵−𝐽𝑅_𝑆p LIT measurement

𝑆^−90°(𝑥, 𝑦)

At various bias:

- 𝑉₁ - 𝑉₂ - 𝑉₃ - 𝑉_𝑟𝑒𝑣

Electroluminescence measurement

Dissipated power 𝑝(𝑥, 𝑦)

Local series resistance

𝑅_𝑠(𝑥, 𝑦) 𝑆^−90° ∝ p

Current density 𝐽(𝑥, 𝑦)

Local electrical parameters 𝐽₀₁, 𝐽₀₂, 𝑛₂, 𝑅_𝑃 2 𝑑𝑖𝑜𝑑𝑒𝑠 𝑚𝑜𝑑𝑒𝑙

Local DIV simulation

Current density of short circuit

𝐽_𝑠𝑐

STC LIV

𝐽 = 𝐽_𝑠𝑐 − 𝐽_{𝑑𝑎𝑟𝑘}

Local LIV simulation Local electrical performance parameters

𝐹𝐹, 𝜂, 𝑉_𝑜𝑐, 𝐽_𝑠𝑐

Measurement Result coming from LIT measurement Result coming from measurement other than LIT

• Use of 2 tools developed by O. Breitenstein at Max Planck Institute: EL-Fit and Local I-V 2.

• Improvement of the extraction protocol:

• Study of image overlay bias and creation of pre-processing routines for measured images;

• Maximising the signal-to-noise ratio by choosing suitable measurement parameters: lock-in frequency depending on the materials making up the module, duty factor, acquisition time, voltage bias …

APPLICATION OF THE PROTOCOL ON THE CASE OF PV MODULES LOADED IN BENDING Experimental set-up

× 2

• 3 point bending test on composite PV modules.

• Bending is applied:

• Parallel to ribbons

• Perpendicular to ribbons

𝐽₀₁ 𝐽₀₂ 𝑅_𝑆 𝐺_𝑃 = 1/𝑅_𝑃 𝜂 𝑉_{𝑚𝑝𝑝,𝑐𝑒𝑙𝑙}

Local electrical parameters before bending test

𝑅_𝑠

log(𝐽₀₁)

log(𝐽₀₂)

𝜂 = 5,2% 𝜂 = 18,4%

𝜂 = 14%

Local electrical parameters of a PV module loaded in bending

Evaluation of the method’s reliability

• Consideration of simulated series resistance under illumination

• Simulated curve is more reliable than the superposition principle based curve.

Global efficiency:

• Before break: 18,2%

• After break: 17,1%

• Application of the method to support the development of new cells, interconnections or module technologies.

• May be used for the monitoring of electrical defects for various ageing tests.

Detection of cell break by

DIV monitoring

0 10 20 30 40

0 0,4 0,8

Current density [mA/cm²]

Voltage [V]

Measured LIV

Simulated LIV

LIV simulated from DIV (superposition principle)

Local electrical parameters after bending test

The authors would like to thank Otwin BREITENSTEIN for his technical support.