Building Integrated Photovoltaics (BIPV): Review, Potentials, Barriers and Myths

To date, none of the predictions that have been made about the emerging BIPV industry have really hit the target. The anticipated boom has so far stalled and despite developing and promoting a number of excellent systems and products, many producers around the world have been forced to quit on purely economic grounds. The authors believe that after this painful cleansing of the market, a massive counter trend will follow, enlivened and carried forward by more advanced PV technologies and ever-stricter climate policies designed to achieve energy neutrality in a cost-effective way. As a result, the need for BIPV products for use in construction will undergo first a gradual and then a massive increase. The planning of buildings with multifunctional, integrated roof and façade elements capable of fulfilling the technical and legal demands will become an essential, accepted part of the architectonic mainstream and will also contribute to an aesthetic valorisation. Until then, various barriers need to be overcome in order to facilitate and accelerate BIPV. Besides issues related to mere cost-efficiency ratio, psychological and social factors also play an evident role. The goal of energy change linked to greater use of renewables can be successfully achieved only when all aspects are taken into account and when visual appeal and energy efficiency thus no longer appear to be an oxymoro

Building Integrated Photovoltaics (BIPV): Review, Potentials, Barriers and Myths

To date, none of the predictions that have been made about the emerging BIPV industry have really hit the target. The anticipated boom has so far stalled and despite developing and promoting a number of excellent systems and products, many producers around the world have been forced to quit on purely economic grounds. The authors believe that after this painful cleansing of the market, a massive counter trend will follow, enlivened and carried forward by more advanced PV technologies and ever- stricter climate policies designed to achieve energy neutrality in a cost-effective way. As a result, the need for BIPV products for use in construction will undergo first a gradual and then a massive increase. The planning of buildings with multifunctional, integrated roof and façade elements capable of fulfilling the technical and legal demands will become an essential, accepted part of the architectonic mainstream and will also contribute to an aesthetic valorisation. Until then, various barriers need to be overcome in order to facilitate and accelerate BIPV. Besides issues related to mere cost-efficiency ratio, psychological and social factors also play an evident role. The goal of energy change linked to greater use of renewables can be successfully achieved only when all aspects are taken into account and when visual appeal and energy efficiency thus no longer appear to be an oxymoron

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

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 during the module encapsulation process. The resulting EVA gel content after encapsulation is an important criterion for the module encapsulation quality control. Normally, the determination of gel content is achieved using a tedious solvent extraction method. In this paper, a fast and nondestructive detection method on the EVA gel content based on the optical reflection is explored. First, the homogeneity of the EVA gel content distribution after the standard EVA encapsulation process is studied. Then, the feasibility of the proposed optical approach applied to transparent modules is investigated. After that, a method is developed to apply it to opaque modules by incorporating a mirror into the module construction. It was found that the haze factor of the reflected light correlates well with the EVA gel content in the opaque modules. This proof-of-concept work could lead to the development of a fast and nondestructive tool for detecting the EVA gel content in both transparent and opaque PV modules, which is promising for integration as an inline diagnostic tool in the module manufacturing line

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

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 module is needed to ensure long-term reliability. Several testing procedures exist that use a metric derived from the force at interface failure to characterize the adhesion. It has, however, not been demonstrated that those metrics relate directly to the interfacial adhesion (defined as the surface energy density needed to break interfacial bonds), and the obtained results usually relate to an apparent adhesion strength. In this work, we describe a new design for compressive-shear testing of polymer layers bonded to rigid substrates. We use it to characterize real interfacial adhesion of ethylene-vinyl acetate (EVA) and polyvinyl-butyral (PVB) to a glass substrate before and after degradation in damp-heat. Our results show that a peak-force based metric is unable to capture the evolution of adhesion through degradation, and a new metric based on the elastic strain energy of the encapsulant is proposed. Moreover, we show that PVB adhesion to glass is much more affected by damp-heat exposure where polymer saturation takes place, in comparison with the adhesion of EVA to glass. The presented characterization protocol is a powerful tool that can help in assessing the reliability of an encapsulant facing specific degradation conditions. Copyright © 2012 John Wiley & Sons, Ltd

Towards in-line determination of EVA Gel Content during PV modules Lamination Processes

Poly (ethylene-co-vinyl acetate) (EVA) is the major polymer used for photovoltaic (PV) modules encapsulation. Its degree of cross-linking (related to its gel content) is taken as a major quality reference. Differential Scanning Calorimetry (DSC) has been proven to be fast and effective but is to determine the gel content, however, destructive for the PV module. With the aim to develop a non-destructive quality assessment tool, a detailed discussion on the DSC thermogram of EVA PV encapsulant is presented here. A possible path towards a fast and non-destructive method for determing EVA gel content is proposed based on the DSC analysis

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

New challenges in solar architectural innovation

Among the century’s main challenges, climate change and the need for energy sources diversification are of great importance. In this context, renewable energies undoubtedly have an important role to play. Photovoltaic (PV) electricity is especially well suited to face these energy challenges. It is now established that the low thin film photovoltaic panels production costs will allow, even in continental climate, to reach low electricity cost, providing easy installation, public acceptance and high reliability. However, architectural considerations are often neglected in the current integration of PV panels. Taking into consideration specific architectural aspects like the surface appearance and the colour of the PV modules can become the key for the successful development of new, well integrated solar systems. To achieve this goal, our team, within the Archinsolar [1] project framework, works on the development of new generation of photovoltaic elements based on silicon thin films technologies (amorphous and micromoph). These new elements will be ultra-reliable and manufacturable at a very low cost, allowing a good architectural integration, respectful of the environment, landscape and built environment. Genera

Innovative Solution for Building Integrated Photovoltaics

Among the main challenges of our century, the climate change and the need of diversification of the energy sources are of most importance. Renewable energies undoubtedly have an important role to play, photovoltaic (PV) electricity being especially well suited to face these energy challenges. However, the current integration of PV panels often comes without architectural consideration. In this context, the Archinsolar project [1] aims to develop a new generation of photovoltaic elements based on silicon thin films technologies (amorphous and micromorph), ultra-reliable and manufacturable at a very low cost, allowing a unique architectural integration, respectful of the bui lt environment and overall landscape. Here we will present our new developments on innovative PV elements including colored PV panels and a solar tile using a composite back-structure

Solar module and its production process

The present invention relates to a solar module comprising a front sheet, a transparent solar cell and a structured reflecting layer comprising color patterned portions. The solar cell has a transparency of at least 5%, preferably at least 10%, more preferably at least 20%, said transparency being defined as being transparent to an incident light beam having a wavelength between 350nm and 2µm, said transparency being defined over the whole surface of said solar cell. Moreover, the structured reflecting layer is chosen in such a way that the solar module presents a colored pattern to an observer or to an imaging system positioned to the incident light side of the solar cell. Such solar modules have reflected colored patterns in the visible and /or the near-infra red part of the spectrum and can be easily incorporated into the architecture of the buildings