STABILITY OF BLACK INTERCONNECT COATINGS FOR SOLAR PHOTOVOL-TAIC MODULE APPLICATIONS

Aesthetics is crucial in the development of Building Integrated Photovoltaic (BIPV) products. Manufacturers strive to mask, typically through expensive manual processes, the reflective metallic interconnects to obtain uniform module colors. Inks offer an automated alternative but must be implemented in the production line and remain stable, maintaining their appearance over time. In this study, three black metallic ribbons were tested: one commercially pre-coated and two coated with UV-curable inkjet printing. Accelerated UV-light exposure was applied according to IEC standards on coupons mimicking glass/backsheet (G/Bs) samples including encapsulant with and without UV blockers. Additionally, one-cell modules with ink-coated ribbons were fabricated using a laboratory-designed automatic inkjet printer and exposed to accelerated UV ageing. Results showed that the commercially available coated ribbon remained stable after 120 kWh/m2 of UV exposure. However, UV-curable inkjet inks caused color changes in the encapsulant around metallic interconnects, regardless of the encapsulant used or the presence or not of UV blockers in the encapsulant. Ink #1 exhibited the most color change under UV-dose. Its main component, 2-phenoexyethyl-acrylate (2-PEA), photodegraded and caused yellowing. An early sign of degradation with a slight increase of 22% in carbonyl index (CI) was observed after 15 kWh/m2 of UV exposure. Encapsulants with UV blockers successfully mitigated 2-PEA photodegradation on G/BS laminates; however, color change occurred with ink #1 despite their application. Using this ink on PV modules results in color change, but the electrical performance remains relatively stable, with less than a 3% power loss after 360 kWh/m2 of UV exposure

Promoting a Sustainable Diffusion of Solar PV Electricity in Africa: Results of the CODEV Project

In this work we present the result of a collaboration between the Polytechnic Schools of Dakar (ESP) and Lausanne (EPFL) on the testing and monitoring of solar photovoltaic modules. The collaboration has involved the exchange of knowledge, methodologies and data, and, in particular, the analysis of the aging of PV modules exposed to the hot semiarid climate of Dakar for eight years. With the aim of promoting a focus on quality and reliability, the long-term goal of the collaboration would be to set-up a testing laboratory for PV modules and systems in Dakar and a training center. The testing laboratory will be working in close collaboration with the University and should potentially have a “lean” and easy-replicable structure. The implementation of a third-party institution able to assess independently the quality of components and support system developers and installers in the design, commissioning and maintenance of PV projects is crucial to promote a “sustainable” diffusion of solar electricity in Africa, particularly when considering the residential and commercial/industrial rooftop PV market segment. By minimizing risk, focus on quality should promote a virtuous cycle leading to: (1) mitigation of financing costs of solar projects, therefore, considerably reducing the overall costs of this technology, (2) increase positive perception and awareness about PV

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

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 accelerated ageing laboratory testing performed at different combinations of stress factors (temperature, relative humidity, and voltage). By modeling the effect of each stress factor in a step-wise approach, we obtain a model for the PID at constant stress conditions, which agrees well with models that can be found in the literature for full-size modules. Our model is obtained complementing existing models by introducing a term that describes a linear dependence of module’s power degradation on the magnitude of the applied voltage. Since in field installations PV modules are connected in strings and exposed to different potential – and, therefore, stress – levels, this latter term is needed to approach real field conditions. Finally, we present the first attempts to model PID outdoor degradation in different climate conditions based on the proposed model and on the indoor-determined coefficients for the devices tested. The outdoor prediction model makes use of Typical Meteorological Year (TMY) data for a specific location

Vetro e Fotovoltaico: due Mondi Sempre piu' Vicini

Il mondo del fotovoltaico è stato fino ad oggi dominato dal silicio. Tuttavia, una grossa potenzialità di riduzione dei costi del FV, risiede in quella che viene definita la seconda generazione del fotovoltaico: le tecnologie a film sottile. La grossa potenzialità di riduzione dei costi dei film sottili risiede in particolare nella possibilità di risparmiare notevolmente sulla quantità del materiale semiconduttore impiegato per realizzare tali dispositivi e per l’alto grado di automazione che le linee di produzione di questi moduli raggiungono.JRC.H.8-Renewable energie

Silicio: Presente e Futuro del Silicio del FV

Oltre il 90% dei moduli oggi in commercio sono in Silicio, elemento che rappresenterà ancora a lungo la principale materia prima del fotovoltaico. Sono ora in fase di studio nuovi processi di produzione dei wafer di Silicio, alcuni quasi maturi per venire applicati nella produzione industriale e che potrebbero rendere il fv assai competitivo con le fonti di energia tradizionali.JRC.H.8-Renewable energie

Silicio: Presente e Futuro del FV

Oltre il 90% dei moduli oggi in commercio sono in Silicio, elemento che rappresenterà ancora a lungo la principale materia prima del fotovoltaico. Sono ora in fase di studio nuovi processi di produzione dei wafer di Silicio, alcuni quasi maturi per venire applicati nella produzione industriale e che potrebbero rendere il fv assai competitivo con le fonti di energia tradizionali.JRC.H.8-Renewable energie

Modelling the performance of amorphous and crystalline silicon in different typologies of building-integrated photovoltaic (BIPV) conditions

In this work we use and further elaborate a previously proposed model to describe the daily performance ratio of amorphous (a-Si) and crystalline silicon (c-Si) photovoltaic solar modules under real operating conditions. For both technologies, the model was validated against three years of data collected from the outdoor test field at Supsi for a conventional ventilated free-rack mounted installation (south facing, 45(circle)-tilt). In the present work, we expand the simulations to model the performance of the same technologies for the same location and to include building integrated (BIPV) installation conditions. For simplicity, we consider two extreme cases: (a) a south-facing facade installation (90(circle)-tilt) and (b) a perfectly horizontal one (0(circle)-tilt). The angle-of-incidence response of the modules is then used to quantify reflection losses, which are very significant in summer and winter for the facade and horizontal installation, respectively. Further, compared to ventilated ones, fully integrated PV modules exhibit average operating temperatures that can reach an offset of +20(circle)C in days of clear sky conditions. This offset is used to model the operating temperatures - and performance losses - of the BIPV modules. The model, whose main limitation is the focus on days of clear sky conditions, allows assessing the distinguished contributions, and peculiar time-phases, of each effect to the yearly energy performance of the devices under test. (C) 2017 Elsevier Ltd. All rights reserved

Modification to the Standard Reference Environment (SRE) for Nominal Operating Cell Temperature (NOCT) to Account for Building Integration

In this paper we have investigated the use of modification to the ¿Standard Reference Environment¿ to account for Building Applied PV (BAPV) and Building Integrated PV (BIPV) applications. The values of the NOCT rise from the open-rack mounted to BAPV and finally to maximum values under BIPV conditions. The NOCT values for the thin-film glass/glass modules are generally higher than the crystalline glass/polymer modules for each of the three mounting options. The impact of changing the module operating condition from open-circuit to resistive load is a clear lowering of the NOCT value of approximately 3oC for the thin-film glass/glass open-rack mounting condition. The resistive load had practically no impact for the BAPV and BIPV cases. Further work is needed to determine if the results of this study will lead to the definitions of new ¿reference environments for building integrated products¿ or the application of some multiplication factor to the current NOCT value to account for the installation method.JRC.DG.F.8-Renewable Energy (Ispra

One-type-fits-all-systems: Strategies for preventing potential-induced degradation in crystalline silicon solar photovoltaic modules

In this work, we investigate the relationship between potential-induced degradation (PID) and the bill of material used in module manufacturing. We manufacture samples with different combination of materials, using two types of solar cells (conventional vs PID-free c-Si cells), two types of ethylene-vinyl acetate (EVA) films with low/high resistivity, and two types of backsheets with, respectively, low/high breathability properties, and subject the mini-modules to extended PID testing. Our results clearly indicate that, when using a breathable polymeric backsheet, to have a "PID-free" module the combination of PID-free cells and high-resistive EVA encapsulants is recommendable. The use of a conventional c-Si cell in combination with a high-resistive EVA encapsulant is still more effective than the use of PID-free cells in combination with low-quality EVA. Further, our results initially show that the breathability properties of the backsheet have apparently no influence on PID degradation. A second set of experiments using sandwich structures with increased resistance properties to water ingress (ie, glass and backsheets with barrier layers as rear covers and an edge sealant), however, indicates that preventing or reducing the diffusion of moisture in the encapsulant layer plays a role in further mitigating the impact of PID. This finding is supported by simulations of moisture ingress in the sandwich structures. Finally, we show that the use of a glass rear cover-compared with a polymeric backsheet-does not contribute in worsening the PID effect. On the contrary, by reducing moisture ingress in the front encapsulant layer, it delays the occurrence of PID