Publications de Hengyu Li | EPFL Graph Search

Thermo-mechanical stability of lightweight glass-free photovoltaic modules based on a composite substrate

Christophe Ballif, Alessandro Francesco Aldo Virtuani, Valentin Chapuis, Hengyu Li, Laure-Emmanuelle Perret Aebi, Ana Cristina Oliveira Martins

Lightweight PV modules are attractive for building-integrated photovoltaic (BIPV) applications, especially for renovated buildings, where the additional load bearing capacity is limited. This work focuses on the development of a lightweight, glass-free pho ...

ELSEVIER SCIENCE BV2018

Modeling potential-induced degradation (PID) in crystalline silicon solar cells: from acceleratea-aging laboratory testing to outdoor prediction

Christophe Ballif, Eleonora Annigoni, Alessandro Francesco Aldo Virtuani, Hengyu Li, Laure-Emmanuelle Perret Aebi, Fanny Sculati-Meillaud, Marko Jankovec, Federico Paolo Galliano

We present a mathematical model to predict the effect of potential-induced degradation (PID) on the power output of c-Si modules in different climates. For the experimental part, we manufacture mini-modules made of two c-Si p-type cells, and use accelerate ...

2016

In-Situ Monitoring of Moisture Ingress in PV Modules Using Digital Humidity Sensors

Christophe Ballif, Fanny Sculati-Meillaud, Hengyu Li, Laure-Emmanuelle Perret Aebi, Eleonora Annigoni, Marko Jankovec, Federico Paolo Galliano

A new in-situ moisture monitoring technique for photovoltaic (PV) modules is proposed using miniature digital humidity and temperature sensors. The sensors were embedded in three different ethylene-vinyl-acetate (EVA) stacks and proved to be resistant to l ...

Ieee-Inst Electrical Electronics Engineers Inc2016

Fast and non-destructive detection on the EVA gel content in photovoltaic modules by optical reflection

Christophe Ballif, Hengyu Li, Laure-Emmanuelle Perret Aebi

Poly(ethylene-co-vinyl acetate) (EVA) has been the dominating material in the photovoltaic (PV) encapsulant market for decades, owing to its superior cost-performance balance. To achieve its desired material properties, EVA undergoes a curing reaction duri ...

Ieee-Inst Electrical Electronics Engineers Inc2015

Effect of Cooling Press on the Optical Transmission through Photovoltaic Encapsulants

Christophe Ballif, Hengyu Li, Laure-Emmanuelle Perret Aebi, Yun Luo

In certain laminators for poly (ethylene-co-vinyl acetate) (EVA) encapsulation process of photovoltaic modules, cooling press (CP) is applied to the module after encapsulation. Here, the effect of CP on the optical transmission through common PV encapsulan ...

Taylor & Francis Inc2015

The effect of cooling press on the encapsulation properties of crystalline photovoltaic modules: residual stress and adhesion

Christophe Ballif, Hengyu Li, Laure-Emmanuelle Perret Aebi, Yun Luo, Valentin Chapuis

A high-quality encapsulation process is crucial to ensuring the performance and long-term reliability of photovoltaic (PV) modules. In crystalline Si technology-based modules, poly (ethylene-co-vinyl acetate) (EVA) is the most widely used PV encapsulant. I ...

Wiley-Blackwell2015

Open the Black Box : Understanding the Encapsulation Process of Photovoltaic Modules

Hengyu Li

EPFL2013

Optical transmission as a fast and non-destructive tool for determination of ethylene-co-vinyl acetate curing state in photovoltaic modules

Christophe Ballif, Hengyu Li, Laure-Emmanuelle Perret Aebi, Yun Luo

Poly(ethylene-co-vinyl acetate) (EVA) is the primary polymer used for encapsulation of photovoltaic (PV) modules. Its degree of cross-linking (gel content) is taken as a major quality reference. The EVA gel content is normally measured by Soxhlet extractio ...

2013

Compressive-shear adhesion characterization of polyvinyl-butyral and ethylene-vinyl acetate at different curing times before and after exposure to damp-heat conditions

Christophe Ballif, Valentin Chapuis, Hengyu Li, Laure-Emmanuelle Perret Aebi

Photovoltaic (PV) module efficiency and reliability are two factors that have an important impact on the final cost of the PV electricity production. It is widely accepted that a good adhesion between the encapsulant and the different substrates of a PV mo ...

Wiley-Blackwell2012

Insights into the encapsulation process of photovoltaic modules: GC-MS analysis on the curing step of Poly (ethylene-co-vinyl acetate) (EVA) encapsulant

Christophe Ballif, Hengyu Li, Laure-Emmanuelle Perret Aebi, Yun Luo

Appropriate encapsulation schemes are essential in protecting the active components of the photovoltaic (PV) module against weathering and to ensure long term reliability. For crystalline cells, Poly (ethylene-co-vinyl acetate) (EVA) is the most commonly u ...

Ismithers2012