Air cooling powered by façade integrated coloured opaque solar thermal panels

For building integration of solar-powered energy systems, aesthetic aspects play an importantrole. Covering a standard solar collector with a coloured glazing, opaque to the human eye but highly transparent to solar energy, permits a perfect architectural integration of solar thermal panels into glazed building façades. The thermal energy produced can be used for both solar heating and cooling, as well as for domestic hot water. The principle of the coloured appearance is based on interference in the thin-film coating on the reverse side of the cover glass. Different interference filters based on nano-composite materials deposited by the solgel method were presented at CISBAT 2007 [1]. Currently, we are developing new plasma-deposition processes, which are more suitable for industrial large-scale production. A new state-of-the-art ultra-high vacuum (UHV) system for magnetron sputtering deposition of novel nano-composite solar coatings has recently been designed, constructed, and installed at the Solar Energy and Building Physics Laboratory (LESO-PB). Up to five different magnetron sources can be used simultaneously, in reactive and non-reactive mode. The geometric configuration of the chamber has been optimised for best film homogeneity and allows the deposition on substrates up to 100 mm in diameter. The optical and electronic properties of thin films are closely interrelated and highly relevant for solar coatings. Photoelectron spectroscopy provides information on the coating structure, the deposited material and its chemical state inside the coating, as well as the nature of the interface between different layers. A system for ESCA analysis (Electron Spectroscopy for Chemical Analysis) has recently been installed and put into operation at LESO-PB. By ellipsometry and spectrophotometry, we can determine exactly the different optical properties of the coating, such as layer thickness, refractive index, or absorption coefficient. This provides best conditions for highly efficient research and development on new materials for further optimisation of the coloured interference filters.First results have been obtained with our new experimental infrastructure and will be presented in this contribution

Coloured coatings for glazing of active solar thermal façades by reactive magnetron sputtering

For building integration of solar-powered energy systems, aesthetic aspects play an important role. Covering a standard solar collector with a coloured glazing, opaque to the human eye but highly transparent to solar energy, permits a perfect architectural integration of solar thermal panels into glazed building façades. The thermal energy produced can be used for both solar heating and cooling, as well as for domestic hot water. The principle of the coloured appearance is based on interference in the thin-film coating on the reverse side of the cover glass. Different interference filters based on nano-composite materials deposited by the solgel method were presented at CISBAT 2007 [1]. Currently, we are developing new plasma-deposition processes, which are more suitable for industrial large-scale production. A new state-of-the-art ultra-high vacuum (UHV) system for magnetron sputtering deposition of novel nano-composite solar coatings has recently been designed, constructed, and installed at the Solar Energy and Building Physics Laboratory (LESO-PB). Up to five different magnetron sources can be used simultaneously, in reactive and non-reactive mode. The geometric configuration of the chamber has been optimised for best film homogeneity and allows the deposition on substrates up to 100 mm in diameter. The optical and electronic properties of thin films are closely interrelated and highly relevant for solar coatings. Photoelectron spectroscopy provides information on the coating structure, the deposited material and its chemical state inside the coating, as well as the nature of the interface between different layers. A system for ESCA analysis (Electron Spectroscopy for Chemical Analysis) has recently been installed and put into operation at LESO-PB. By ellipsometry and spectrophotometry, we can determine exactly the different optical properties of the coating, such as layer thickness, refractive index, or absorption coefficient. This provides best conditions for highly efficient research and development on new materials for further optimisation of the coloured interference filters. First results have been obtained with our new experimental infrastructure and will be presented in this contribution

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

Laminated glazing with coloured reflection and high solar transmittance suitable for solar energy systems

Laminated and etched glazing unit for architectural integration of solar energy systems comprising a substrate delimited by two main faces and a multi-layered interference filter also delimited by two main faces, one main face of said substrate being adapted to be in contact with an incident medium, the other main face being in contact with a main face of said interference filter, the other main face of said interference filter being adapted to be in contact with an exit medium; said incident medium having a refractive index ninc = 1, said substrate having a refractive index nsubstrate defined as follows : 1.45≤ nsubstrate ≤ 1.6 at 550 nm, and said exit medium being defined as follows 1.45≤ nexit ≤ 1.6 at 550 nm; and wherein said unit is designed in such a way that the following requirements are met : 1a) The saturation of the colour, given by C*ab = √ (a*)2 + (b*)2, according to the CIE colour coordinates L*, a* and b* under daylight illumination CIE-D65 is higher than 8 at near-normal angle of reflection, except for grey and brown. 1b) The visible reflectance at near-normal angle of reflection Rvis is higher than 4%. 1c) The variation of the dominant wavelength λMD of the dominant colour MD of the reflection with varying angle of reflection Θr is smaller than 15 nm for Θr < 60°. 1d) The total hemispherical solar transmittance at near-normal incidence is above 80%

Interference filter with angular independent orange colour of reflection and high solar transmittance, suitable for roof-integration of solar energy systems

olar glazing unit, suitable for photovoltaic modules and solar thermal collectors, comprising a substrate delimited by two main faces and a multi-layered interference filter also delimited by two main faces, one main face of said substrate being adapted to be in contact with an incident medium, the other main face being in contact with a main face of said interference filter, the other main face of said interference filter being adapted to be in contact with an exit medium; said incident medium having a refractive index ninc = 1, said substrate having a refractive index nsubstrate defined as follows : 1.45 ≤ nsubstrate ≤ 1.6 at 550 nm, and said exit medium having a refractive index nexit = 1 or defined as follows 1.45 ≤ nexit ≤ 1.6 at 550 nm; and wherein said unit is designed in such a way that the CIE colour stability ΔE*Norm, as observed under daylight illumination CIE D65 at higher angles of reflection Θr (Θr > 10°), is less than 15 or ΔE*Norm ≤ (Θr / 3°) for 10° < Θ ≤ 60°

Reactively sputtered coatings on architectural glazing for coloured active solar thermal façades

Covering a standard solar thermal collector with a coloured glazing, which is opaque to the human eye but highly transparent to solar energy, permits a perfect architectural integration of solar panels into glazed building façades. The colours are based on interference in the thin-film coating on the reverse side of the glass. Coloured thin-film filters with optimised energetic performance and angular stability in their coloured reflection were deposited by reactive magnetron sputtering. For substrates up to 100 mm in diameter the geometric configuration of the deposition chamber and the process parameters were optimised. The optical properties of the coatings were determined by spectroscopic ellipsometry and spectrophotometry. Furthermore, by means of a window test bench, the CIELAB colour coordinates of real-size glasses were determined as a function of the viewing angle. It was also demonstrated that the colour of solar collector glazing can be matched to colours of commercial windows. In comparison to uncoated glass panels, the presented coloured samples for solar thermal panels have an energy loss of only 2.8–4.5% at normal solar incidence. This difference reduces for higher angles of incidence. Thus, taking into account the angular distribution of solar radiation, the energetic losses are even lower

Optical and morphological characterisation of low refractive index materials for coatings on solar collector glazing

Nanostructured coatings based on the elements Si, O, Mg, and F have been deposited as thin films by solegel dip-coating in a particle-free atmosphere. The refractive index of the prepared SiO2 and quaternary MgeFeSieO thin films has been determined from spectrophotometric and ellipsometric data. The morphology of those thin films has been observed by TEM. Nanoporous SiO2 coatings with a pore size smaller than 3 nm (TEM) and a pore volume fraction of 30% (as inferred from ellipsometric measurements) have been achieved. They are characterised by significantly lower refractive index values (approx. 1.32 at 550 nm) than compact SiO2 (approx. 1.46). Quaternary MgeFeSieO thin films are characterised by a surprisingly low refractive index (approx. 1.26 at 550 nm), even lower than that of dense MgF2 coatings (approx. 1.38). Preliminary results of transmission electron microscopy suggest that these films are of nanocomposite nature. In both cases, highly transparent samples have been produced in a single dip-coating step followed by simple thermal annealing in air. Broad spectral transmittance maxima are observed exceeding values of 98.5% (nanoporous SiO2) and 99.5% (quaternary MgeFeSieO films). The quaternary films might exhibit a higher ageing stability than porous SiO2 films with respect to pore-filling and could therefore be a promising alternative for single-layered anti-reflection coatings as well as for multi-layered coloured coatings on solar collector glazing

71Ga NMR in chalcogenide and chalco-halide glasses

International audienceChalcogenide and chalco-halide glasses containing gallium have been studied through 71Ga solid state nuclear magnetic resonance (NMR). An unusual line shape of the 71Ga NMR spectra has been observed for the first time. This line shape was ascribed to the preferential local symmetry existing around gallium atoms in these glasses which are characterized by the covalent character of their chemical bonds. Then, the local environment of gallium in Ga2S3-GeS2-CsCl glasses was studied by 71Ga NMR as a function of the ionic cesium chloride CsCl concentration. In this system, CsCl directly interacts with Ga by forming anionic complexes, modifying its environment. The Czjzek's electric field gradient distribution and its recent extension have been successfully applied to reconstruct the experimental 71Ga NMR spectra. These results highlight the evolution of local surroundings of Ga atoms in the glass network as a function of the CsCl concentration