Solar Glass Research Articles

Building integration of semitransparent perovskite-based solar cells: Energy performance and visual comfort assessment

This study presents a prediction of the yearly energy production and visual comfort benefits deriving from the adoption of building integrated semitransparent photovoltaic windows. Measured electrical and optical properties of neutral-colored solid-state planar heterojunction perovskite cells, characterized by promising transparency and photovoltaic conversion efficiency, were applied to a hypothetic photovoltaic glazing. Such experimental data were used as input to estimate annual energy production and visual comfort effects. The effect of different climate conditions was also investigated. A south-oriented test-room was modelled, assuming two window-to-wall ratios (WWRs) for office buildings, 19% and 32%, respectively. Energy yield was calculated at different locations showing figures between 20 and 30kWh/m2 per year, with negligible reduction (not exceeding 3% in the hottest climates) when cell temperature was taken into account. Visual comfort assessment was carried out using two typical metrics: Useful Daylight Illuminance (UDI) and Daylight Glare Probability (DGP), comparing the performances of a photovoltaic glass with those of a commercial solar control glass and of a clear glass, acting as a reference. We found that the use of photovoltaic glass, independent of the location latitude, showed a significant increase in UDI values respect to clear glasses and performances comparable to solar control glasses. With reference to DGP, the use of photovoltaic glass allowed the reduction of occurrence of high DGP values (>0.45) of about 12–23%, depending on the location. Finally, we compared the annual energy production of building integrated photovoltaic cells to the annual use of electric energy for artificial lighting, finding that in most of the cases the annual energy production overcomes the amount of electric energy used for artificial lighting.

Interface Crystallization of Ceria in Porous Silica Films for Solar Applications

Antireflective (AR) coatings with photocatalytic activity for solar cover glasses are extensively investigated at present, mostly in multilayer systems including titania. In this study, bifunctional single coats from porous silica in combination with up to 33 mol % ceria were prepared by sol–gel dip-coating on low-iron soda-lime float glass. After heat treatment for one hour at 350 °C, the coated glasses were characterized. Solar transmittance decreased with increasing ceria content, whereas photocatalytic activity increases. Crystallization of cubic ceria was detected by grazing incidence X-ray diffraction. Chemical depth profiling by secondary neutral mass spectrometry revealed the enrichment of cerium at the coating surface as well as at the interface to the glass substrate. Self-assembled ceria crystallization at the interfaces resulted in a three-layered mesostructure of the coating, which was verified by field-emission scanning electron spectroscopy. Cubic ceria crystals at the interface act as a barrier for the sodium diffusion from the substrate, which prevents the poisoning of the photocatalyst, while those crystals at the surface act as an electron donor for photooxidation processes, both enabling adequate photocatalytic activity. The triple-layer architecture with the sequence of high/low/high refractive index materials allows for optical interference sustaining the AR-function.

The Thermal and Optical Behavior of Multilayer Low-E Solar Control Glass Surfaces

Glass is one of the most popular and versatile building materials used today. One reason is because of its constantly improving solar and thermal performance. And one way this performance is achieved is through the use of passive and solar control low-e coatings. In architecture, the proper use of natural light can help reduce the energy consumption of a building (by reducing the heat load for heating - based on the superior of solar contributions, with an appropriate glass type and daylighting). This paper aims to present the thermal behavior of multilayer glass surfaces, low-e solar control and highlight differences to ordinary glass.

DYNAMIC RESEARCH OF SOLAR CELLS / DINAMINIS SAULĖS ELEMENTO TYRIMAS

Solar cells are one of the most popular renewable energy generation technologies, because they are reliable, low operating and maintenance costs, to conclude without any moving parts and is a boundless source of energy. In any solar cell can avoid mechanical vibrations, which may produce the solar cell glass, damage to the inner structure. In order to determine the influence of mechanical vibrations of the solar cell structure was carried out theoretical and experimental modal analysis. The study found dangerous solar cell frequencies and their deformation and optimize the method of attachment which provides a better solar cell stability. Saulės elementai – vieni populiariausių atsinaujinančių energijos gavybos technologijų, nes jie patikimi, jų mažos eksploatavimo ir priežiūros išlaidos, šie elementai sudaryti be jokių judančių dalių ir yra beribis energijos šaltinis. Bet saulės elementas neišvengia mechaninių virpesių, kurie gali įskelti saulės elemento stiklą, pažeisti vidinę konstrukciją. Siekiant nustatyti mechaninių virpesių įtaką saulės elemento konstrukcijai, buvo atliktos teorinės ir eksperimentinės modalinės analizės. Tyrime buvo rasti pavojingi saulės elemento dažniai ir jų deformacijos, rastas optimalus tvirtinimo būdas, kuris suteikia geresnį saulės elemento stabilumą.

Surface reliability of annealed and tempered solar protective glasses: Indentation and scratch behavior

Solar glass is exposed to mechanical contact cleaning and sand particle impact during operation in outdoor environments resulting in optical efficiency loss as well as decrease in mechanical integrity, durability and reliability. The current study investigates the mechanical behavior of two different solar surface glasses through a series of low and high load indentation and scratch experiments. Nanoindentation experiments are performed on the glass substrate in order to measure the hardness and elasticity moduli at different depths below the surface. Scratch experiments are also preformed to find the critical load for the extent of plastic zone or the onset of micro-cracking. The influence of heat treatment for photovoltaic glasses on mechanical properties such as elastic modulus and hardness, and surface properties such as friction coefficient and elastic recovery is examined in this study in which heat treatment is found to affect both mechanical and surface properties. Also, different resistance behavior is observed in low and high load experiments as well as in indentation vs. scratch experiments.

Transmittance of selected nanostructurized solar glasses designated via relative change in electrical parameters of silicon solar cells

Photovoltaics is one of the most promising technologies for electricity production. In the future, photovoltaics could be an effective and safe source of energy.In this work were present the results of the analysis of a special solar glasses transmissivity coefficient used as protective cover of photovoltaic cell. Antireflective glass due to its unique physical properties eliminate reflections and significantly increasing light transmission. The study of the relative change in the electrical parameters of photovoltaic cells ,with and without coats, as open-circuit current I SC and the maximum power point MPP are presented in this paper. Research were undertaken with using the solar simulator QuickSun130CA, Class AAA+, under Standard Test Conditions.

Anti-reflective Coated Glass and its Impact on Bifacial Modules’ Temperature in Desert Locations

Without any doubt does anti-reflective coating (ARC) on solar glass help to boost the annual module performance in the range of 3 to 4% for monofacial modules with Sunarc AR coated glass under moderate climate conditions [1] which certainly differ from desert climates. In this work three bifacial and one monofacial photovoltaic modules, with different glass coatings, are installed in a desert region as the Atacama Desert in Chile, with the optimum tilt for the location and same surrounding conditions. From the results it is observed that the glass/glass bifacial modules with ARC on both glass sheets can achieve a mean performance ratio (PR) of up to 5% higher than a module without coating in any of both glasses. It is also observed that the thermal dependence of PR for modules with ARC on both glasses and its operative temperature are larger compared to modules without coated glass.

Optical modifications at the intrinsic absorption threshold in soda lime silicate glass by Ag+–Na+ ion exchange

Silicate glass slides with different alkali metal and alkaline earth metal content were doped with different amounts of silver by Ag+–Na+ ion exchange in order to obtain glass showing strong luminescence in the visible spectral range suitable for solar glass or UV-LED-lenses. After excitation at λ=325nm (Eex=3.815eV) an enhancement of more than two orders of magnitude for broad white emission centered at about Eem≈2.3eV is achieved. Modifications of doped glass are investigated by absorption spectrophotometry for monitoring the intrinsic absorption threshold and by polarized photoluminescence spectroscopy for evaluating the enhanced emissions. The luminescence enhancement requires a modification of the intrinsic absorption threshold due to a decreased optical band gap. This is explained by a locally driven redox-reaction, which also should form at least one reduced silver containing species. The formed bright intra-ionic luminescence center creates a structure with at least three energy levels. This center is assumed to be closely related with the band structure and should cause a creation of holes, electrons or one of their bound states like excitons or polarons.

Design of multi-layer anti-reflection coating for terrestrial solar panel glass

To date, there is no ideal anti-reflection (AR) coating available on solar glass which can effectively transmit the incident light within the visible wavelength range. However, there is a need to develop multifunctional coating with superior anti-reflection properties and self-cleaning ability meant to be used for solar glass panels. In spite of self-cleaning ability of materials like TiO2 and ZnO, these coatings on glass substrate have tendency to reduce light transmission due to their high refractive indices than glass. Thus, to infuse the anti-reflective property, a low refractive index, SiO2 layer needs to be used in conjunction with TiO2 and ZnO layers. In such case, the optimization of individual layer thickness is crucial to achieve maximum transmittance of the visible light. In the present study, we propose an omni-directional anti-reflection coating design for the visible spectral wavelength range of 400–700 nm, where the maximum intensity of light is converted into electrical energy. Herein, we employ the quarter wavelength criteria using SiO2, TiO2 and ZnO to design the coating composed of single, double and triple layers. The thickness of individual layers was optimized for maximum light transmittance using essential Mcleod simulation software to produce destructive interference between reflected waves and constructive interference between transmitted waves.

Normal impact of sand particles with solar panel glass surfaces

An analytical elasto-plastic model coupled with a transient impact model is developed to study single normal impact of small sand particles on solar panels glass surfaces. Nanoindentation measurements are performed on two commercial photovoltaic protective glasses, namely annealed and tempered, to extract their mechanical properties required for the impact model. The model is qualitatively validated through sandblasting experiments. Evaluation of the impacting sites using scanning electron microscopy shows significant plastic impressions of Vickers-like indentation for small sand particle impact. Employing the analytical model, parametric study is performed to examine the glass deformation due to single sand impact using different corner radii, impact speeds and glass types. The proposed model is used to predict plastic damage due to normal sand impact.

A smart building material for low/zero carbon applications: heat insulation solar glass—characteristic results from laboratory andin situtests

Heat insulation solar glass (HISG) is a recently developed smart building material to minimize energy consumption of building sector. HISG might be presumed to be a conventional photovoltaic glazing product; however, it is completely unique by having some characteristic features such as superior thermal insulation, which is competitive with triple-glazed windows using argon as inert gas, acoustic and thermal comfort, self-cleaning ability owing to TiO2 nano-coating on module surface and extraordinary energy saving potential in both summer and winter. In our previous works, comprehensive experimental and numerical works have been carried out for power generation and thermal insulation performance of HISG under various climatic conditions. Within the scope of this research, optical- and lighting-related performance parameters of this smart building material are evaluated through extensive laboratory and in situ tests. Shading coefficient, visible light intensity, and UV and IR penetration are investigated via the tests conducted in real operating conditions. It is achieved from the results that the shading coefficient of HISG is only 0.136, which yields almost 80% reduction in solar heat gain compared with ordinary glazing. It is also observed from the in situ tests that HISG has a %100 UV and 99% IR blocking rate, which is of vital importance in terms of human health and thermal comfort conditions. Glaring effects are totally resolved via HISG, which is still a challenge for the buildings with conventional glazing products, especially in summer.

A novel route to prepare hydrophobic and durable antireflective hybrid silica coating by sol-gel method

The application of antireflective coatings to the glass covers of solar thermal collectors, allows increasing the efficiency of the whole system. The work presented here describes the room temperature synthesis of highly transparent and hydrophobic silica coatings using tetraethylorthosilicate (TEOS) as a precursor and polydimethylsiloxane (PDMS) as a hydrophobic modifying agent via a simple dip coating technique. Then, the films were characterized by measuring contact angle and optical transparency, Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) measurements. A new two-step method by double layer of acidic and basic sols was employed. Results showed the maximum transmittance of the antireflective solar glass with double layer coating is about 95.02% at 565 nm wavelength, which is about 4% higher than the substrate glass. The durability of the materials used in solar systems is a key point since they should keep their initial properties during the operational lifetime. In this work, the stability of the optical properties of the films after one year at room temperature in an environment has been achieved, thanks to the application of a hydrophobic treatment and two step-catalyzed sols to the coating. The addition of PDMS to the silica sols improved the hydrophobicity of the coating, and prevented to some extent the coating from cracking which occurred in a pure inorganic thick antireflective coating. It was observed that the obtained silica films become hydrophobic with the introduction of the hydrophobic organic group and static water contact angle (97°) was obtained for the silica film prepared with double layer of acidic/basic coating.

Zeolite Crystals Embedded Nanotextured Coating with Hydrophobic Surface: An Innovation Toward Next Generation Solar Cover Glass for Efficient Light‐Harvesting

A zeolite crystals embedded nanotextured hard coating with hydrophobic surface is fabricated on low iron borosilicate glass to enhance the efficiency of photovoltaic systems through advance light‐trapping. The surface roughness generated from embedding 3D nanocrystals enhances absorption of sunlight by reducing reflection loss, and capturing maximum incident light to construct higher electricity and passive solar gain. Furthermore, the deposition of a very thin hydrophobic layer facilitates self‐cleaning. The sunlight to electrical power generation capability of this nanotextured coating on glass is around 2.7% higher compared to the commercial millimeterscale textured (translucence) cover glass on the standard silicon solar cell. These nanotextured self‐cleanable coatings exhibiting antidazzle and positive temperature effects, would be an ideal candidate to fabricate next generation durable cover glass on solar panel. Moreover, the elevated visual transparency along with light‐trapping efficiency of this coating can explore its additional outdoor solar applications on the glass walls in greenhouses.

Six-layer antireflection TiO2/SiO2 coatings for solar covers: role of Triton and PDMS additives

This manuscript aims to investigate the effect of Triton (TX-100) and polydimethylsiloxane (PDMS) on six-layer TiO2/SiO2 coatings. In this study, the sol–gel method was employed to prepare titania and silica sols. In order to obtain a multi-layer antireflective coating on glass, two additive materials were used for identifying the best way to produce the antireflective and durability coatings. The coatings prepared in this work were characterized using field-emission scanning electron microscopy, atomic force microscopy, Fourier-transformed infrared spectroscopy, X-ray diffraction analysis, UV–visible spectrophotometer and contact angle measurement. Both of multi-layer containing PDMS and Triton coatings showed over 98 % transmittance but the PDMS modified six-layer coating was more durable than the Triton modified coating and remained stable after outdoor exposure for 8 months. The addition of PDMS to the sols improved the hydrophobicity of the coatings and prevented the adsorption of humidity. High transmittance and excellent durability make this coating appropriate for solar glasses.

Structural changes of surfaces of spacecraft solar array protective glasses being irradiated by 20-keV electrons

When irradiating K-208 and CMG glasses by 20-keV electrons with flux densities of 1010<φe<2×1011cm−2s−1 in vacuum 10−4Pa, electrostatic discharges accompanied by plasma emission and destruction of glass surfaces were observed. Examination of glasses by atomic force microscopy (AFM) showed significant difference in structural changes of surfaces of K-208 and CMG samples irradiated by equal flux densities within the range from 2.0×1010 to 9.0×1010cm−2s−1 that can be explained by different mechanisms of removal of charge accumulated in glasses. Surface discharges generating channels on surfaces of K-208 and CMG glasses appear when φ⩾7.4×1010cm−2s−1 and φ⩾8.7×1010cm−2s−1 respectively. In average, if radiation conditions are the same and φ⩾1.4×1011cm−2s−1, the channels are 1.5 times deeper in K-208 than in CMG.

Dye Sensitized Solar Modules with Embedded Silver Lines

ABSTRACTWe employed ultrasonic spray deposition method for production of high quality FTO thin film TCOs to be employed in a silver embedded grid type and monolithic type dye sensitized solar modules. Produced films exhibited dense and crystalline structure with homogeneous coverage on solar glass substrates. Obtained resistivity and light transmission values of FTO are comparable to commercially available FTO coated glasses used widely in the industry. After optimization of the chemistry and deposition conditions, 10x10 cm sized glass substrates could be produced for large area photovoltaic modules. Produced FTO films were used to construct monolithic type and parallel type dye sensitized solar modules. Monolithic modules yielded 1.61% active area efficiency value. In order to enhance the active area of the parallel type modules, silver grid lines were embedded in glass substrate and FTO coating was deposited on the lines. Due to this effective design, we achieved 2.42% efficiency on the total area of the 55x55 mm sized module compared to 2.90% active area efficiency, proving that this design is suitable for enhancing efficiency values of parallel type dye sensitized solar modules.

Preparation of hydrophobic SiO2/PMHS sol and ORMOSIL antireflective films for solar glass cover

Adjusting the porosity of films to obtain a suitable refractive index is one of the key technical concerns of the porous silica antireflective coatings (ARCs) preparation via sol–gel process. However, it is challenging to reduce the refractive index below than 1.20 with the conventional process. In the meantime, residual silanol groups (Si–OH) on coated glasses may deteriorate the weatherability of the ARCs. In this paper, a novel organically modified silicate (ORMOSL) ARCs with good hydrophobicity property and variable refractive index from 1.18 to 1.36 were prepared by modifying the silica sol with polymethylhydrosiloxane (PMHS). In the reaction with PMHS, silica micelle was cross-linked and regrew to synthesize partly clustered ORMOSIL micelle. The ORMOSIL micelles were coated on the soda-lime glasses to form monolayer ARCs. The antireflection and hydrophobicity properties of the coated glasses were significantly improved, i.e., optical transmittance up to 7% gain in the visible range with 130° water contact angle was obtained. Satisfyingly, the SiO2–PMHS sol showed excellent stability with a shelf life of up to 40–105days. In addition, the structure and morphology of the ORMOSIL films were investigated and “Cross-link and fill” model was proposed to explain the effect of PMHS content on the properties of sols and ARCs.

Energy saving potential of heat insulation solar glass: Key results from laboratory and in-situ testing

HISG (heat insulation solar glass) is a recently developed multi-functional glazing technology to mitigate energy consumption of buildings. HISG can generate electricity similar to conventional PV (photovoltaic) glazing products when exposed to sunlight, however it differs from them by having some extraordinary characteristic features such as thermal insulation, which is competitive with Argon filled triple glazed windows, acoustic comfort, remarkable energy saving potential and self-cleaning ability owing to TiO2 nano coating. Within the scope of this research, latest results from laboratory and in-situ testing of HISG are presented in terms of its key role in mitigating heating and cooling demand of buildings as well as clean energy generation. Lighting and thermal comfort related parameters such as shading coefficient, UV, IR and visible light intensity are also investigated through the tests conducted in real operating conditions. It is achieved from the results that instant electricity generation of HISG is 16% higher than that of standard PV glazing owing to its nano layer reflective film. Shading coefficient of HISG is only 0.136, which provides almost 80% reduction in solar heat gain compared to ordinary glazing. Indoor air temperature measured from HISG test house in summer time is very close to the ambient temperature, whereas it is found to be 14.7 °C higher in ordinary glass test house due to greenhouse effect. Annual heating and cooling demand tests indicate that HISG provides 38 and 48% energy saving in heating and cooling season, respectively.

Broadband antireflective double-layer mesoporous silica coating with strong abrasion-resistance for solar cell glass

Power conversion efficiency of polycrystalline silicon solar cells increased about 1.3% with this broadband antireflective double-layer mesoporous silica coating.

Energy efficiency research of heat insulation solar glass on buildings

Energy efficiency research of heat insulation solar glass on buildings