Colour properties and glazing factors evaluation of multicrystalline based semi-transparent Photovoltaic-vacuum glazing for BIPV application

This is the final version of the article. Available from Elsevier via the DOI in this record.In support of open access research, all underlying article materials (data, models) can be accessed upon request via email to the corresponding author.Low heat loss vacuum glazing offers high heat insulation for indoor space, which reduces the building's heating energy demand. However, the transparent nature of this glazing allows similar daylight to double glazing that creates discomfort glare. Double pane semi-transparent type photovoltaic (PV) glazing introduces control of solar heat gain, daylight and generates clean electricity. The transparent portion between regularly distributed PV cells allows light penetration. Addition of these two technologies can offer low heat loss PV-vacuum glazing that will control heat loss, heat gain, and daylight and generate renewable power. In this work, two different areas of multicrystalline PV cells were employed to form 35% and 42% transparent PV-vacuum glazing. Spectral characterisation, glazing factor and entering light quality through the transparent part of this PV-vacuum glazing were evaluated. Colour rendering and correlated colour temperature of this glazing were compared with an electrically actuated switchable suspended particle device glazing.This work has been conducted as part of the research project ‘Joint UK-India Clean Energy Centre (JUICE)’ which is funded by the RCUK’s Energy Programme (contract no: EP/P003605/1)

Carbon counter electrode mesoscopic ambient processed & characterised perovskite for adaptive BIPV fenestration

This is the final version. Available on open access from Elsevier via the DOI in this recordIn this work, carbon counter electrode perovskite was developed at the laboratory environment and building integrated photovoltaic (BIPV) window application using this material was investigated. At 1 sun (1000 W/m2) continuous incident solar radiation from an indoor simulator, this particular type of perovskite had 8.13% efficiency. Average solar and visible transmittance of this perovskite BIPV window was 30% and 20% respectively. Solar heat gain for different incident angle was evaluated for this perovskite glazing. For the University of Exeter, Penryn (50.16° N, 5.10° W) UK location, solar heat gain coefficient (SHGC) or solar factor (SF) varied from 0.14 to 0.33 at the highest and lowest incident angle respectively. Overall heat transfer coefficient (U-value) of 5.6 W/m2K was realized for this glazing while calculation was performed by window performance analysis programme, WINDOW 6.0. Daylight glare control potential of this glazing was investigated using subjective rating methods and comfortable daylight penetrated through glazing in a typical cloudy condition. Colour properties of this material showed that 20% visible transmittance is threshold limit, and below this value colour or visual comfort using this glazing is not achievable.Engineering and Physical Sciences Research Council (EPSRC

Realization of poly (methyl methacrylate) encapsulated solution-processed carbon-based solar cells: emerging candidate for buildings’ comfort

This is the final version. Available from the publisher via the DOI in this record.The self-assembling characteristics allow carbon nanomaterials to be readily explored, environmentally benign, solution-processed, low-cost, and efficient solar light-harvesting materials. An effort has been made to replace the regular photovoltaic device’s electrodes by different carbon allotropebased electrodes. Sequential fabrication of carbon solar cells (SCs) was performed under ambient conditions, where FTO/ graphene/single-walled carbon nanotubes/graphene quantum dotsfullerene/carbon black paste layers were assembled with poly- (methyl methacrylate) (PMMA) as an encapsulating layer. The PMMA layer provides significant improvement toward the entry of water vapor, hence leading to stability up to 1000 h. The photoconversion efficiency of the PMMA-encapsulated carbon SC has been increased by ∼105% and the stability decreased by only ∼10% after 1000 h of exposure to environmental moisture. Besides, the building integrated photovoltaic window properties achieved using this carbon SC were also investigated by using the color rendering index and the correlated color temperature, which can have an impact on the buildings’ occupants’ comfort. This study leads to an extensive integration to improve carbon-based materials because of their effective and useful but less-explored characteristics suitable for potential photovoltaic applicationsEngineering and Physical Sciences Research Council (EPSRC

Investigations on performance enhancement measures of the bidirectional converter in PV–wind interconnected microgrid system

This is the final version. Available from MDPI via the DOI in this record. In this work, a hybrid microgrid framework was created with the assistance of a photovoltaic (PV) and wind turbine (WT) generator. Additionally, bidirectional control mechanisms were implemented where an AC system was integrated with permanent magnet synchronous generator (PMSG)-based WT and a DC system was integrated with a sliding mode algorithm controlled maximum power point tracker (MPPT)-integrated PV system. The wind and PV interconnected microgrid system was mathematically modeled for steady-state conditions. This hybrid microgrid model was simulated using the MATLAB/SIMULINK platform. Optimal load management strategy was performed on a chosen hybrid microgrid system. Various case studies pertaining to connection and disconnection of sources and loads were performed on the test system. The outcomes establish that the system can be kept up in a steady-state condition under the recommended control plans when the network is changed, starting with one working condition then onto the next

Color Comfort Evaluation of Dye-Sensitized Solar Cell (DSSC) Based Building-Integrated Photovoltaic (BIPV) Glazing after 2 Years of Ambient Exposure

This is the final version. Available on open access from the American Chemical Society via the DOI in this recordData availability: in support of open access research, all underlying article materials (data, models) can be accessed upon request via email to the corresponding author.Transmitted external daylight through semitransparent type building integrated photovoltaic (BIPV) windows can alter the visible daylight spectrum and render different colors, which can have an impact on building's occupants' comfort. Color properties are defined by the color rendering index (CRI) and correlated color temperature (CCT). In this work, a less explored color comfort analysis of N719 dye-sensitized TiO2 based dye-sensitized solar cell (DSSCs) BIPV window was characterized and analyzed after 2 years of ambient exposure. Three different DSSCs were fabricated by varying TiO2 thickness. The reduced average visible transmission was observed while enhanced color properties were obtained for all three DSSCs. This study could pave way to future developments in the area of BIPV technology using DSSC in terms of their long-term exploration.Engineering and Physical Sciences Research Council (EPSRC

Hydrophilic and superhydrophilic self-cleaning coatings by morphologically varying ZnO microstructures for photovoltaic and glazing applications

This is the author accepted manuscript. The final version is available from the American Chemical Society via the DOI in this record In support of open access research, all underlying article materials (data, experimental details) can be accessed upon request via email to the corresponding author.Transparent, superhydrophilic materials are indispensable for their self-cleaning function, which has become an increasingly popular research topic, particularly in photovoltaic (PV) applications. Here, we report hydrophilic and superhydrophilic ZnO by varying the morphology for use as a self-cleaning coating for PV applications. Three different ZnO microstructures, such as ZnO nanorods (R-ZnO), ZnO microflowers (F-ZnO), and ZnO microspheres (M-ZnO), were developed by hydrothermal methods. The surface morphology by using X-ray diffraction (XRD), wettability behavior by using water contact angle (WCA) measurements, structural and optical properties by using photoluminescence (PL), Raman, and UV-vis spectrophotometry, and defect estimation by using X-ray photoelectron spectroscopy (XPS) of the ZnO nanostructured films were systematically investigated. XRD confirmed the formation of the hexagonal wurtzite structure of ZnO. The average crystallite sizes of prepared R-ZnO, F-ZnO, and M-ZnO were found to be 28.95, 11.19, and 41.5 nm, respectively. The band gap values of ZnO nanostructures were calculated from the UV-vis absorption spectrum and found to be 3.6, 3.3, and 3.1 eV for R-ZnO, F-ZnO, and M-ZnO, respectively. The WCAs for R-ZnO and F-ZnO were 20.2 and 11.19°, respectively, while M-ZnO behaved like a superhydrophilic material having a WCA of 2.8°.RCUK’s Energy ProgrammeEPSRC IAA Gran

Evaluation of thermal performance for a smart switchable adaptive polymer dispersed liquid crystal (PDLC) glazing

This is the final version. Available from Elsevier via the DOI in this record. A new class of smart window technologies are gaining interest as they have the functionality to control dynamic solar radiation, shading, ventilation and energy production. They are capable of improving buildings’ energy performance by adapting to different climate conditions and bring thermal and visual comfort for occupants. Polymer-dispersed liquid crystal (PDLC) is a smart switchable window that changes its optical transmissions from translucent to transparent when an alternating electric current stimulus is introduced. The present paper discusses the results of an indoor investigation for the optical and thermal performance of a PDLC glazing system. The spectral transmittance of the investigated PDLC was evaluated for both the translucent and transparent states using UV–vis–NIR (1050) spectrophotometer. In addition, the thermal investigation was carried out in an indoor condition utilising a test cell equipped with a small scale of PDLC glazing, which was exposed to (1000, 800, 600, 400 W/m2) solar radiation for 180 min. The optical evaluation showed that the investigated PDLC glazing offered low transmission for UV (8%) and NIR (44%) in the translucent state, respectively. The result of SHGC was 0.68 and 0.63 for the transparent and translucent states, respectively, which indicates that the investigated sample could be more effective in reducing heat loads in a cold dominated climate. The U-value for the PDLC glazing was 2.79 W/m2 for the transparent and 2.44 W/m2 translucent.Engineering and Physical Sciences Research Council (EPSRC

Smart glazing thermal comfort improvement through near-infrared shielding paraffin incorporated SnO2-Al2O3 composite

This is the final version. Available on open access from Elsevier via the DOI in this recordBuilding's energy conservation signifies a lowering in building energy consumption without sacrificing thermal comfort. Window glazing is the most suitable approach to the built environment that can be controlled through its sustainable development for global energy consumption. In this work, for the first time, paraffin incorporated SnO2-Al2O3 composite coating is developed on a 5 cm × 5 cm glass using a screen-printing method, which signifies an intelligent cooling behaviour for a comfortable indoor environment irrespective of their emplacement. The composite energy-saving properties exhibit less transmission of infra-red light while keeping high visible light transmittance behaviour resulting superior heat-shielding performance. The composite coated glass's average indoor temperature profile remains at ∼30 °C when the outside temperature reaches a maximum of 45 °C during outdoor testing. While the same composite film is set inside, the indoor average temperature maintains ∼30 °C, whereas outside temperature reaches a maximum of 80 °C. The distinct temperature profile for composite coated glass indicates high transparency of 80% throughout the experiment. Interestingly paraffin has been incorporated into the composite, offering no leakage, translucent characteristics, and limited water ingress. In comparison, non-coated glass is failed to provide them with a comfortable, stable indoor temperature. We believe this study envisages the recent technological innovations combined with phase change material and transparent infrared absorber together as a composite for window glass for warmer climates, which further leads to significant energy savings compared with plain glass.Engineering and Physical Sciences Research Council (EPSRC

Role of Hafnium Doping on Wetting Transition Tuning the Wettability Properties of ZnO and Doped Thin Films: Self-Cleaning Coating for Solar Application

This is the author accepted manuscript. The final version is available from the American Chemical Society via the DOI in this record.Herein, we successfully synthesized high-quality Hf-ZnO thin films with various Hf contents (0, 3, 6, 9, 12, and 15 at. %), which showed both superhydrophilic (6% Hf-ZnO) and ultrahydrophobic (15% Hf-ZnO) wetting behavior. Different characterization methods were opted to recognize the structural (XRD, SEM, AFM) and defect properties (XPS) of the pristine and doped materials, to understand the mechanisms underlying the tuning of wetting behavior (contact angle). Hafnium doping plays a noteworthy role in tuning the morphology of the ZnO nanostructures, roughness of the material surface, generation of defects, Lewis acid–base interactions, and wettability properties. We achieved a superhydrophilic surface with 6% Hf-ZnO owing to a smooth surface, less basicity, and maximum concentration of oxygen vacancies, and also an ultrahydrophobic surface with 15% Hf-ZnO because of the rough surface, high basicity, and minimum concentration of oxygen vacancies. The as prepared Hf-ZnO samples showed stable performance (stability, wearability, weatherability, and antifouling) under real-life conditions marking them multifunctional and biosafe material to be effectively used in solar and building’s window. A wetting mechanism was established to relate the wetting behavior of the samples to oxygen vacancies (active sites for water dissociation: resulted due to charge mismatch of host cation (Zn2+) by the doped cation (Hf4+)), roughness (smooth surface (Wenzel) with minimum Rrms (0.588) portraying hydrophilic property and rough caltropic surface (Cassie–Baxter) with maximum Rrms (2.522) portraying hydrophobic property), basicity (H2O: Lewis Base; ZnO: Lewis acid; HfO2: Lewis base) and morphology (tube-like structure (0–6% Hf-ZnO) and caltrop-like structure (12–15% Hf-ZnO)).Engineering and Physical Sciences Research Council (EPSRC)University of Exete

Incorporating Solution-Processed Mesoporous WO3 as an Interfacial Cathode Buffer Layer for Photovoltaic Applications

This is the final version. Available on open access from the American Chemical Society via the DOI in this recordDextran templating hydrothermal synthesis of monoclinic WO3 exhibits excellent specific surface area of ~110 m2 /g and a mono-modal pore distribution with the average pore diameter of ~20 nm. Dextran plays a crucial role to generate porosity on WO3. The role of supporting dextran has been investigated and found to be crucial to tune the surface area, porosity and morphology. The photo-luminescence and X-ray photoelectron spectroscopy studies reveal about the existence of oxygen vacancies in sub-stoichiometric, which creates localized defect states of WO3 as synthesized through this templating method. The highly mesoporous WO3 have been further explored as an interfacial cathode buffer layer (CBL) in dye sensitized solar cells (DSSCs) and perovskite solar cells (PSCs). A significantly enhanced photo-conversion efficiency has been boosted up the performance of the counter electrode used in traditional DSSC (as platinum) and PSCs (as carbon) devices by ~48% and ~29%, respectively. The electrochemical impedance and the incident photon to current conversion efficiency (IPCE) studies were also analysed in order to understand the catalytic behaviour of the WO3 interfacial CBL for both DSSC and PSC, respectively. The much higher surface area of WO3 enables rapid electron hopping mechanism, which further benefits for higher electron mobility resulting in higher short circuit current. Through this study, we are able to unequivocally establish the importance of buffer layer incorporation, which can further help to integrate the DSSC and PSC devices towards more stable, reliable and enhanced efficiency generated device. In spite of that, using WO3 constitutes an important step towards the efficiency improvement of the devices for futuristic photo-electrochromic or selfpowered switchable glazing for low energy adaptive building integration.Engineering and Physical Sciences Research Council (EPSRC