Installation photovoltaïque intégrée au bâti

thumb|Habitations avec des panneaux solaires intégrés au bâti à Fribourg-en-Brisgau. Les installations photovoltaïques intégrées au bâti sont des installations photovoltaïques se substituant aux éléments de construction traditionnels des maisons et immeubles. La filière est souvent désignée par son acronyme anglais BIPV (). Histoire L’intégration du photovoltaïque au bâti apparait dans les années 1980 aux États-Unis, ces systèmes installés sur des bâtiments connectés au réseau ne sont pas montés en surimposition mais intégrés esthétiquement car le photovoltaïque arrive en ville et ne se limite plus au site isolé. Cette notion est apparue pour la première fois il y a dans le programme européen Solar House de Joule II. Dans les années 1990, la production de modules et de systèmes s’intégrant au bâti commence car la demande augmente mais c'est à partir des années 2000 que ce secteur se développe vraiment grâce aux primes d'intégration sur le tarif d'achat. Alors que la

Interfacial engineering for competitive Dye-Sensitized Solar Cells production

Natalie Flores Diaz

Renewable energy deployment and implementation of a circular economy will play a crucial role in decreasing CO2 emissions to meet the target from the Paris agreement. Dye-sensitized solar cells (DSSCs) can be designed in various colors and transparency for building-integrated photovoltaics (BIPV). This emerging technology has gained significant attention for its remarkably high power conversion efficiency (PCE) under indoor lighting up to 34%. To improve the performance of DSSCs, various approaches to study and reduce the interfacial electron recombination from the conduction band of the semiconductor to the electrolyte were implemented in this thesis. One of the approaches was the design of a tandem electrolyte containing two redox species, the radical AZADO (AZ+/0) and the [Co(bpy)3]2+/3+ complex. DSSCs with tandem electrolytes showed increased open-circuit voltage (VOC) up to 1009 mV and enhanced PCE of 9.15%. The VOC enhancement was determined to result from the higher redox potential of (AZ+/0) and the slower electron recombination rate. These findings demonstrate the advantages of employing tandem electrolytes to improve the VOC and overall performance of DSSCs. To decrease the solvent's volatility and the interfacial electron recombination in cobalt-based electrolytes, hyperbranched networks (HB) were designed through a click thiol-ene reaction between a thiol-siloxane and an acrylate monomer. The formed polymers were denoted HB1 (thiol-siloxane and PEGMA) and HB2 (thiol-siloxane and PEGMA). The addition of 20% of HB polymers to a cobalt-based electrolyte retained up to 98% of their initial weight until 150°C. The devices employing 10%(v/v) of HB1 attained the highest PCE under AM1.5 of 8.52%, comparable to 9.36% for the cobalt reference electrolyte. All the HB-electrolytes presented higher VOC values than the cobalt reference due to an upward shift in the CB of TiO2 and longer electron lifetimes. It was determined that the HB-polymers reduce the electron recombination and enhance the photovoltaic performance under low light intensity leading to a PCE of 23.19% under 1000 lux compared to 20.37% for the Co-reference. We then developed a new dye, R7, with a strong electron-donating PAH core and BPT2 as the central building block and a bulkier HF donor to decrease electron recombination at the interface TiO2/electrolyte. We found that in the presence of a copper electrolyte, the dye R7 outperformed devices with R6. EIS revealed that the bulky HF-donor introduction effectively suppressed the electron recombination between the TiO2 surface and the redox shuttle. Additionally, we employed a co-sensitized system of R7+Y123 to reach the outstanding parameters of JSC of 16.15 mAcm-2, VOC of 1035 mV, FF of 0.76 to achieve a top PCE of 12.7%. To the best of our knowledge, this is the highest for copper-based DSSCs using a blue photosensitizer. Lastly, the interfacial phenomena in DSSCs with carbon counter electrodes (CCEs) and copper-based electrolytes were studied to determine the feasibility of the production of monolithic DSSCs with copper-based hole-transporting materials. It was found that the electron transport in devices with CCEs is in the same order of magnitude as those with PEDOT. However, the devices with CCEs presented a decrease of 2 orders of magnitude in the recombination resistance, resulting in decreased VOC and JSC, leading to a PCE of 17% compared to 24.5% for PEDOT devices under 1000 lux illumination.

EPFL2021

Ultra-lightweight PV module design for building-integrated photovoltaics

Ana Cristina Oliveira Martins

Most of the existing solutions for Building Integrated PV (BIPV) are based on conventional crystalline Silicon (c-Si) module architectures (glass-glass or glass-backsheet) exhibiting a relatively high weight (12-20 kg/m2). We are working on the development of robust and reliable lightweight solutions with a weight target of 6 kg/m2. Using a composite sandwich architecture and high thermal conductivity materials, we show that it is possible to propose lightweight PV modules compliant with the IEC 61215 thermal cycling test. We further show that we are able to upscale the size of the devices from 2 cells up to 16-cell modules.

2017

Robust glass-free lightweight photovoltaic modules with improved resistance to mechanical loads and impact

Ana Cristina Oliveira Martins

In several countries, building-integrated photovoltaics (PV) solutions could contribute to the growth of total installed PV capacity. However, in some circumstances, the relative high weight (10–15 kg/m2) and lack of aesthetics of PV may constitute a barrier to its diffusion. In this work, we propose a glass-free lightweight solution (6 kg/m2) compliant with hail and mechanical load tests as prescribed by the IEC 61215-2:2016. The low weight is achieved by substituting the conventional glass cover with a polymer multi-layer resistant to hail impacts and the conventional polymer/glass backsheet by an innovative composite backsheet. A total of two module design contributions to impact resistance are highlighted: a global energy dissipation, mostly related to the backsheet properties; and a local energy dissipation, mainly related to the frontsheet properties. These results clearly show that a balance between frontsheet design and backsheet stiffness have to be found in order to maximize hail resistance and mechanical rigidity while minimizing the module’s weight.

2018

Interfacial engineering for competitive Dye-Sensitized Solar Cells production

Natalie Flores Diaz

EPFL2021