Publications by category
Journal articles
Cameron WJ, Alzahrani MM, Yule J, Shanks K, Reddy KS, Mallick TK (2023). Indoor experimental analysis of Serpentine-Based cooling scheme for high concentration photovoltaic thermal systems. Applied Thermal Engineering, 234, 121183-121183.
Motamedi M, Jia G, Yao Y, Shanks K, Yousefi P, Hewakuruppu YL, Rafeie M, Lindner F, Patterson R, Christiansen S, et al (2023). Nanopatterned indium tin oxide as a selective coating for solar thermal applications.
Renewable Energy,
210, 386-396.
Abstract:
Nanopatterned indium tin oxide as a selective coating for solar thermal applications
Indium tin oxide (ITO) coatings have been proposed to reduce thermal emission losses for solar thermal applications. Unfortunately, ITO also has a large amount of free charge carriers (∼1 × 1020 per cm3), which absorb sunlight. To address this issue, we propose a nano-patterned ITO-coated quartz exhibiting both anti-reflectivity (to maximize solar transmission) and low emissivity (to minimize long wavelengths radiative losses). A record small-size nanosphere (∼60 nm) etch mask was prepared via double self-assembly, followed by dry etching and characterisation. In parallel, alternative nanopattern geometries were modelled using the Lumerical FDTD software to optimise short wavelength transmission without diminishing the inherently low emissivity of unetched ITO. It was found that an inverted moth's eye pattern (height = 250 nm and spacing = 80 nm) gave the best results at various solar concentrations (1 sun @ 100 °C, 10 suns @ 400 °C, and 100 suns @ 600 °C), resulting in ∼7% improvement in the solar weighted transmission as well as a similar boost in the overall efficiency factor for selectivity. It was concluded that if the proposed deposition/etching processes can be cost-effectively scaled in a continuous process, it would provide a net performance boost for most solar thermal technologies.
Abstract.
Cameron WJ, Alzahrani MM, Yule J, Shanks K, Reddy KS, Mallick TK (2023). Outdoor experimental validation for ultra-high concentrator photovoltaic with serpentine-based cooling system. Renewable Energy, 215, 118926-118926.
Zhang W, Li J, Xie L, Hao X, Mallick T, Wu Y, Baig H, Shanks K, Sun Y, Yan X, et al (2022). Comprehensive analysis of electrical-optical performance and application potential for 3D concentrating photovoltaic window. Renewable Energy, 189, 369-382.
Li Q, Zhuo Y, Shanks K, Taylor RA, Conneely B, Tan A, Shen Y, Scott J (2021). A winged solar biomass reactor for producing 5-hydroxymethylfurfural (5-HMF).
Solar Energy,
218, 455-468.
Abstract:
A winged solar biomass reactor for producing 5-hydroxymethylfurfural (5-HMF)
Biomass-derived alcohols such as 5-Hydroxymethylfurfural represent a promising intermediary energy and species carriers for hydrogen and value‐added chemical production. Solar-driven reforming of biomass to 5-HMF at the desired reaction condition (e.g. at ~150 °C and ~5 bars) offers a sustainable route, but the lack of a rooftop-based solar biomass reactor represents a substantial impediment. In this work, a unique, low-profile “winged” solar concentrator with an evacuated tube reactor was designed for the renewable production of 5-HMF. The viability of this design was examined in detail, using sucrose as the feedstock for 5-HMF production in the presence of sulfuric acid. The optical study indicated that the winged structure significantly increased the effective concentration ratio (by ~42%) and that the design has a broader acceptance angle (from 60° to 90°) compared to CPC alone. During outdoor experiments, the wings boosted the thermal efficiency from 18% to ~25% when operating at 150 °C, and achieved a maximum 5-HMF yield of ~21 mol % (under a solar irradiance of ~800 W/m2). In parallel, a transient computational fluid dynamics model was developed to further elucidate the heat and mass transfer phenomena inside the reactor and to investigate a broader range of operating conditions and reactor design parameters. The numerical and experimental results were in agreement that a specific energy consumption for 5-HMF production of ~23 kWh/kg was achievable and that a full-scale system (~3 L reactor volume, 2.1 m2 gross area) can produce ~0.45 kg of 5-HMF per day, with an average daily solar input of 5 kWh/m2.
Abstract.
Alzahrani M, Shanks K, Mallick TK (2021). Advances and limitations of increasing solar irradiance for concentrating photovoltaics thermal system.
Renewable and Sustainable Energy Reviews,
138Abstract:
Advances and limitations of increasing solar irradiance for concentrating photovoltaics thermal system
Concentrating photovoltaic-thermal (CPVT) technology harnesses solar energy by increasing the solar density upon cells using optical concentrators. CPVT systems are the focus of ongoing research and improvements to achieve the highest potential for energy harnessing and utilization. Increasing the concentration ratio for high energy generation raises many advances and limitations in the CPVT design. This article highlights the influence of the temperature with an increasing concentration ratio on CPVT components in terms of single-/multi-junction semiconductor materials, primary and secondary optical concentrator materials, and thermal receiver design. To achieve this, the theory of single- and multi-junction solar cell electrical characteristics (Voc,Isc,FF and η) is first explained to understand their dependence on the temperature and concentration ratio. An extensive literature review discussing the advantages, disadvantages, and potential of current CPVT research is given. This includes graphical and tabular summaries of many of the various CPVT design performances. In this review, it has been ascertained that higher concentration ratios raise the temperature at which the performance, operation and reliability of CPVT system are affected. Also, this review indicates that the temperature elevation of the CPVT components is significantly impacted by the optical configuration and their material types and reflectance. A thermal receiver is illustrated as three components: solar cell (heat source), heat spreader (substrates) and its different types, and cooling mechanism. In addition, the article addresses the thermomechanical stress created with intensified illumination, especially with secondary optics, where the optical materials and optical tolerance need to be carefully explored. The economic implications of a high concentration ratio level are briefly considered, addressing the reduction in system cost by enhancing the system efficiency. Suggestions are made throughout the review as to possible improvements in system performance.
Abstract.
Ahmed A, Shanks K, Sundaram S, Mallick T (2021). Energy and exergy analyses of new cooling schemes based on a serpentine configuration for a high concentrator photovoltaic system.
Applied Thermal Engineering,
199Abstract:
Energy and exergy analyses of new cooling schemes based on a serpentine configuration for a high concentrator photovoltaic system
High concentrator photovoltaic is expected to play an increasingly important role in electrical energy production. Controlling multijunction solar cell temperature within the recommended conditions is a key challenge that limits the functionality of this growing technology making the identification of an efficient cooling method an essential requirement. Hence, in this research, new heat sink configurations based on a serpentine design are studied and compared with the straight channel arrangement. To assess the performance of the high concentrator photovoltaic, a 3D model is built for the multijunction cell and heat sink and impact of the heat sink configuration, mass flow rate, and concentration ratio are investigated. The results include solar cell temperature distribution, thermal resistance, pumping power, thermal and electrical energy and exergy efficiencies. The study shows that the straight channel is not recommended for concentration above 1000×, whereas the centre inlet serpentine design can maintain a uniform temperature distribution for the system for concentration up to 2000×. Temperature non-uniformity varies between 18 °C and 5 °C. The highest overall energy and exergy efficiencies reached 78% and 35.2% respectively at concentration of 2000×. The results prove the effectiveness of implementing a serpentine design as a new cooling scheme for the system.
Abstract.
Li J, Zhang W, He B, Xie L, Hao X, Mallick T, Shanks K, Chen M, Li Z (2021). Experimental study on the comprehensive performance of building curtain wall integrated compound parabolic concentrating photovoltaic.
Energy,
227Abstract:
Experimental study on the comprehensive performance of building curtain wall integrated compound parabolic concentrating photovoltaic
A novel concentrating photovoltaic curtain wall (CPV-CW) system integrated with building has been designed, tested and analyzed, and its application potential is determined and improvement suggestions are proposed. It can effectively improve the efficiency of photovoltaic (PV) module and provide a more uniform indoor lighting environment. The concentrator is constructed with truncated stationary asymmetric compound paraboloid. and cyclic olefin copolymer (COC) with high transmittance is selected as its structural material. A model building combined with CPV-CW system curtain wall has been designed and applied to the outdoor experiments. It was tested on its electricity generation efficiency, the internal lighting environment, and thermal insulation ability. According to the real time results, under the clear weather conditions, the transmittance of the CPV-CW system reaches 9.1%. The highest CPV-CW system generation efficiency, 26.5%, could be found in winter, followed by the autumn and summer separately. In addition, CPV-CW system can create a more uniform indoor light environment and meet the requirements of building insulation. Based on the analysis, the CPV-CW system has a broad application prospect for building integrated with concentrating photovoltaic.
Abstract.
Alzahrani M, Roy A, Shanks K, Sundaram S, Mallick TK (2021). Graphene as a pre-illumination cooling approach for a concentrator photovoltaic (CPV) system. Solar Energy Materials and Solar Cells, 222, 110922-110922.
Pickering T, Shanks K, Sundaram S (2021). Modelling technique and analysis of porous anti-reflective coatings for reducing wide angle reflectance of thin-film solar cells.
Journal of Optics,
23(2), 025901-025901.
Abstract:
Modelling technique and analysis of porous anti-reflective coatings for reducing wide angle reflectance of thin-film solar cells
Abstract
. Bio-inspired anti-reflective (AR) coatings with porous graded refractive index structures are known to considerably reduce the reflectance of light at optical interfaces, however, research is lacking for thin-film cell application. Ray Tracing software coupled with the Effective Medium Theory were used to simulate the reflectance of nanostructured coatings placed above a thin-film system. The most optimal coating was paraboloid-shaped, with 300 nm nipple heights and spacings of 15%. The non-zero refractive index ‘step’ aids light trapping and energy absorption. This coating reduced reflectance in the λ = 300–800 nm range by an average of 2.665% and 11.36% at 0∘ and 80∘ incident light, respectively, whilst increasing annual energy output by 4.39% and 5.39% for standard UK roof and vertical window tilts, respectively. Significant wide angle reflectance capabilities are demonstrated at specifically λ = 300 nm and 80∘ incident light, with a reflectance reduction of 19.192%. There are now many promising manufacturing techniques for these porous nanostructures, such as AR or wavelength filtering coatings for photovoltaics. Further understanding of the exact parameters needed to replicate these nanostructures must be explored to proceed.
Abstract.
Alzahrani M, Ahmed A, Shanks K, Sundaram S, Mallick T (2021). Optical component analysis for ultrahigh concentrated photovoltaic system (UHCPV). Solar Energy, 227, 321-333.
Ahmed A, Zhang G, Shanks K, Sundaram S, Ding Y, Mallick T (2021). Performance evaluation of single multi-junction solar cell for high concentrator photovoltaics using minichannel heat sink with nanofluids.
Applied Thermal Engineering,
182Abstract:
Performance evaluation of single multi-junction solar cell for high concentrator photovoltaics using minichannel heat sink with nanofluids
High concentrated photovoltaic systems (HCPV) have demonstrated the potential to achieve high conversion power over conventional photovoltaic panels (PV) especially for areas with high solar irradiance. However, the multi-junction (MJ) solar cells may be subjected to damage if the temperature exceeds 110 °C as recommended by the manufacturer. Hence, in this paper, the overall performance of a 1cm2 MJ solar cell with a mini-channel heat sink subjected to high concentration ratio (500×to2000×) is investigated to find improved method of reducing the cell temperature. The impact of using water, Al2O3/water, and SiO2/water on the effectiveness of heat transfer, temperature distribution on the MJ solar cell, and performance evaluation criteria are studied. Also, the evaluation of the HCPVT system performance is presented. A 3D computational modelling is performed and the experimental measurements for the thermal conductivity are constructed for the different fluids and entered in the simulation. Nanofluids maintain the maximum solar cell temperature at 95.25 °C and 67.1 °C at Reynolds number (Re) of 8.25 and 82.5 respectively and a concentration ratio of 2000×. The overall efficiency of the system increases by 3.82% at Re of 8.25 and a concentration ratio of 500× by using SiO2/water at 5%.
Abstract.
Khalid M, Shanks K, Ghosh A, Tahir A, Sundaram S, Mallick TK (2021). Temperature regulation of concentrating photovoltaic window using argon gas and polymer dispersed liquid crystal films.
Renewable Energy,
164, 96-108.
Abstract:
Temperature regulation of concentrating photovoltaic window using argon gas and polymer dispersed liquid crystal films
Low concentrating photovoltaic (LCPV) system has been studied extensively, which showed excellent potential for the building integration application. However, such a system suffers from higher operating temperatures due to the concentrated light exposed into the solar cell. In this work, two different methods have been used to regulate the operating temperature of the solar cell without the interference of any other external mechanism. Two concepts were used to study the operating temperature of the solar cells are: i) use of Argon gas within the concentrator element, ii) incorporation of polymer-dispersed liquid crystal films (PDLC) on top of the module. In both cases, the power was improved by 37 mW–47 mW when temperature was reduced by 10 °C and 4 °C for the Argon gas-filled module and PDLC integrated module, respectively. In addition, the temperature effect of the PDLC integrated module showed a unique nature of reduction of the short circuit current due to the orientation of the liquid crystal particle, which increased at a higher temperature. The current study, therefore, shows the greater potential of improving the operating efficiency and reduction of solar cell temperature, without the need for additional pumping power such as needed for photovoltaic thermal application.
Abstract.
Sun Y, Liu D, Flor JF, Shank K, Baig H, Wilson R, Liu H, Sundaram S, Mallick TK, Wu Y, et al (2020). Analysis of the daylight performance of window integrated photovoltaics systems.
Renewable Energy,
145, 153-163.
Abstract:
Analysis of the daylight performance of window integrated photovoltaics systems
Integrating photovoltaics into windows provides the possibility of including an additional function of energy production to a conventional building fenestration component. There is no doubt that electrical power can be generated on-site. However, the effect of PV windows on the indoor luminous environment of the space served by them has not been comprehensively researched. This paper investigated the daylight performance of integrating four types of photovoltaics (semi-transparent thin film Cadmium telluride (CdTe) solar cells with 10% and 50% transparency, crystalline silicon solar cells with and without crossed compound parabolic concentrators (CCPC)) to a window of a typical south-facing office under different Window-to-Wall Ratios (WWRs). Annual useful daylight illuminance (UDI), daylight uniformity ratio (UR) and daylight glare probability (DGP) have been analysed based on dynamic simulation using RADIANCE. The simulation results show that windows integrated with crystalline silicon cells and CCPC optics have the potential to provide best daylight availability when compared with standard double glazed windows and other tested PV window prototypes, if it is applied to rooms with large WWRs (e.g. 60% or 75% WWR) at high latitudes (e.g. city of Harbin). Its application also improves the uniformity of daylight spatial distribution and eliminates the risk of glare. Semi-transparent CdTe PV window with 10% transparency can also improve the percentage of working hours that fall into UDI 500–2000lux range, however, it will result in the most sharp illuminance contrasts within the room. Applying all of these tested PV windows can effectively reduce the possibility of glare.
Abstract.
Gadkari D, Shanks KS, Philipp HT, Tate MW, Thom-Levy J, Gruner SM (2020). Characterization of an architecture for front-end pixel binning in an integrating pixel array detector. Journal of Instrumentation, 15(11), T11002-T11002.
Ahmed A, Alzahrani M, Shanks K, Sundaram S, Mallick TK (2020). Effect of using an infrared filter on the performance of a silicon solar cell for an ultra-high concentrator photovoltaic system.
Materials Letters,
277Abstract:
Effect of using an infrared filter on the performance of a silicon solar cell for an ultra-high concentrator photovoltaic system
It is well known that increasing the concentration ratio of concentrator photovoltaics has a positive impact on the power output of the system but can reduce the solar cells performance due to the heightened temperatures. In this paper, we introduce the impact of using an infrared (IR) filter on the performance of a silicon solar cell as a preliminary investigation for an ultra-high concentrator photovoltaic system. The investigation is carried out in terms of the optical characterization of the Fresnel lens and the IR filter. Besides, the performance of the system has been introduced in this paper. The results show that although the IR filter protects the solar cell from damage near the tabbing wire, it reduces the experimental power output of the cell by 46.08% due to the low transmittance of the filter while the cell efficiency increased by 183.3%.
Abstract.
Alzahrani M, Baig H, Shanks K, Mallick T (2020). Estimation of the performance limits of a concentrator solar cell coupled with a micro heat sink based on a finite element simulation. Applied Thermal Engineering, 176, 115315-115315.
Al Siyabi I, Shanks K, Mallick T, Sundaram S (2020). Indoor and outdoor characterization of concentrating photovoltaic attached to multi-layered microchannel heat sink. Solar Energy, 202, 55-72.
Alzahrani M, Ahmed A, Shanks K, Sundaram S, Mallick T (2020). Optical losses and durability of flawed Fresnel lenses for concentrated photovoltaic application. Materials Letters, 275, 128145-128145.
Ahmed A, Shanks K, Sundaram S, Mallick TK (2020). Theoretical Investigation of the Temperature Limits of an Actively Cooled High Concentration Photovoltaic System.
Energies,
13(8), 1902-1902.
Abstract:
Theoretical Investigation of the Temperature Limits of an Actively Cooled High Concentration Photovoltaic System
Concentrator photovoltaics have several advantages over flat plate systems. However, the increase in solar concentration usually leads to an increase in the solar cell temperature, which decreases the performance of the system. Therefore, in this paper, we investigate the performance and temperature limits of a high concentration photovoltaic Thermal system (HCPVT) based on a 1 cm2 multi-junction solar cell subjected to a concentration ratio from 500× to 2000× by using three different types of cooling fluids (water, ethylene glycol and water mixture (60:40), and syltherm oil 800). The results show that, for this configuration, the maximum volumetric temperature of the solar cell did not exceed the manufacturer’s recommended limit for the tested fluids. At 2000× the lowest solar cell temperature obtained by using water was 93.5 °C, while it reached as high as 109 °C by using syltherm oil 800, which is almost equal to the maximum operating limit provided by the manufacturer (110 °C). Overall, the best performance in terms of temperature distribution, thermal, and electrical efficiency was achieved by using water, while the highest outlet temperature was obtained by using syltherm oil 800.
Abstract.
Shanks K, Knowles A, Brierley A, Baig H, Orr H, Sun Y, Wu Y, Sundaram S, Mallick T (2019). An experimental analysis of the optical, thermal and power to weight performance of plastic and glass optics with AR coatings for embedded CPV windows.
Solar Energy Materials and Solar Cells,
200Abstract:
An experimental analysis of the optical, thermal and power to weight performance of plastic and glass optics with AR coatings for embedded CPV windows
A low concentrator photovoltaic is presented and the optical losses within a double glazed window assembly are described. The use of plastic instead of glass is analyzed for its reduced weight and hence greater power to weight ratios. Although the transmittance of glass is higher, the power to weight ratio of the plastic devices was almost double that of the glass counterparts and even higher than the original non concentrating silicon cell. The plastic Topas material was found to be the best performing material overall. Crystal Clear, a plastic resin, had a higher average transmittance but had a lower optical efficiency due to the cold cast manufacturing process in comparison to injection moulding of the other materials. This proves the importance of considering both the materials and their associated manufacturing quality. External quantum efficiencies, optical properties, silicon cell temperatures and performance is analyzed for concentrating photovoltaic devices made of varying optical materials. The measurement methods for optical analysis are given in an attempt to separate the optical losses experimentally. The Silicon cells were found to gain higher temperatures due to the insulating plastic optics in comparison to glass but these effects are eliminated during vertical window orientation where instead the encapsulate dominates the insulation of the cell. The results presented here prove plastic optics to be a worthwhile alternative to glass for use in low concentration photovoltaic systems and have the significant effect of reversing the weight disadvantage concentrator photovoltaic technology has compared to standard flat plate solar panels.
Abstract.
Al Siyabi I, Shanks K, Khanna S, Mallick TK, Sundaram S (2019). Evaluation of concentrating photovoltaic performance under different homogeniser materials.
Materials Letters,
241, 219-222.
Abstract:
Evaluation of concentrating photovoltaic performance under different homogeniser materials
In concentrating photovoltaic (CPV), increasing the incoming sunlight to the solar cell influences the performance of the solar cells. The optical efficiency of the CPV components is a key factor to improve the electrical efficiency. Two types of homogeniser materials (K9 glass and crystal resin) were investigated in the CPV application. The results show a higher power generation of the CPV module when using K9 glass homogeniser compared to the crystal resin homogeniser by 27% due to the high transmittance value of the K9 glass material. In addition, the K9 glass material shows an excellent resistance to the heat produced by the concentrated sunlight compared to the crystal resin material.
Abstract.
Spalding A, Shanks K, Bennie J, Potter U, Ffrench-Constant R (2019). Optical Modelling and Phylogenetic Analysis Provide Clues to the Likely Function of Corneal Nipple Arrays in Butterflies and Moths.
Insects,
10(9).
Abstract:
Optical Modelling and Phylogenetic Analysis Provide Clues to the Likely Function of Corneal Nipple Arrays in Butterflies and Moths.
The lenses in compound eyes of butterflies and moths contain an array of nipple-shaped protuberances, or corneal nipples. Previous work has suggested that these nipples increase light transmittance and reduce the eye glare of moths that are inactive during the day. This work builds on but goes further than earlier analyses suggesting a functional role for these structures including, for the first time, an explanation of why moths are attracted to UV light. Using a phylogenetic approach and 3D optical modelling, we show empirically that these arrays have been independently lost from different groups of moths and butterflies and vary within families. We find differences in the shape of nipples between nocturnal and diurnal species, and that anti-glow reflectance levels are different at different wave-lengths, a result thereby contradicting the currently accepted theory of eye glow for predator avoidance. We find that there is reduced reflectance, and hence greater photon absorption, at UV light, which is probably a reason why moths are attracted to UV. We note that the effective refractive index at the end of the nipples is very close to the refractive index of water, allowing almost all the species with nipples to see without distortion when the eye is partially or completely wet and providing the potential to keep eyes dry. These observations provide a functional explanation for these arrays. of special interest is the finding that their repeated and independent loss across lepidopteran phylogeny is inconsistent with the explanation that they are being lost in the 'higher', more active butterflies.
Abstract.
Author URL.
Shanks K, Ferrer-Rodriguez JP, Fernàndez EF, Almonacid F, Pérez-Higueras P, Senthilarasu S, Mallick T (2018). A >3000 suns high concentrator photovoltaic design based on multiple Fresnel lens primaries focusing to one central solar cell.
Solar Energy,
169, 457-467.
Abstract:
A >3000 suns high concentrator photovoltaic design based on multiple Fresnel lens primaries focusing to one central solar cell
A high concentrator photovoltaic design is proposed of 5800x geometrical concentration ratio based on multiple primary Fresnel lenses focusing to one central solar cell. The final stage optic is of a novel design, made of a high refractive index (n = ∼1.76), to accept light from four different directions but very easily manufactured. The high geometrical concentration of 5800x was chosen in anticipation of the losses accompanied due to alignment difficulties. Two scenarios are however simulated, one with state of the art optics (achromatic Fresnel lenses and 98% reflective mirrors) and one of standard, relatively cheap optics. An optical efficiency of ∼75% is achieved in simulations if high quality optics are utilised, which gives an optical concentration ratio of just over 4300x. Simulating standard optical constraints with less accurate optics results in an optical efficiency of ∼55% which translates to an optical concentration ratio of ∼3000x. In this way the quality of the optics can be chosen depending on the trade of between cost and efficiency with room for future advanced optics to be incorporated at a later date. The optical efficiency of each component is simulated as well as experimentally measured to ensure the accuracy of the simulations. A theoretical acceptance angle of 0.4° was achieved in ray trace simulations for this design which is considered good for such a high concentration level. The need for achromatic Fresnel lenses is apparent from this study to reach optimum performance and concentration but even 55% optical efficiency results in a >3000x concentration not yet experimentally tested. The solar cells irradiance distribution of the design is also presented along with performance and rough cost comparisons to other systems in the literature. The cost of the optics compared to more complex shaped optics is also given.
Abstract.
Sun Y, Shanks K, Baig H, Zhang W, Hao X, Li Y, He B, Wilson R, Liu H, Sundaram S, et al (2018). Integrated semi-transparent cadmium telluride photovoltaic glazing into windows: Energy and daylight performance for different architecture designs.
Applied Energy,
231, 972-984.
Abstract:
Integrated semi-transparent cadmium telluride photovoltaic glazing into windows: Energy and daylight performance for different architecture designs
When integrating photovoltaics into building windows, the photovoltaic glazing modules inhibit the function that glass performs, with the additional function of energy production. Semi-transparent Photovoltaic (STPV) glazing will absorb part of the solar radiation incident on the window surface to generate electrical power. In turn, this affects the overall solar energy and natural daylight penetrating into the indoor space. Various factors determine the building energy performance and indoor comfort level as a result of adopting STPV glazing. The factors regarding window design alone (window size, PV glazing coverage ratio and PV glazing placing position) require rigorous study. In this paper, an innovate model (combined optical, electrical and energy model) was developed to comprehensively evaluate the performance of an office equipped with STPV window and firstly analyse the effect of window design on overall energy efficiency. A double-glazing unit integrated with thin film CdTe solar cells with 10% transparency was electrically characterised by Sandia Array Performance Model (SAPM). The annual energy performance of a typical office served by window integrated STPV glazing was investigated through EnergyPlus simulation for various window designs under five typical climatic conditions in China (using weather files of Harbin, Beijing, Shanghai, Guangzhou and Kunming for representation). The optical performance (defined by a Bidirectional Scattering Distribution Function) of this STPV glazing was also obtained using a ray-tracing technique. Then, the annual daylight performance of the porotype office was assessed using RADIANCE. We found that when compared to a conventional double-glazed system, the application of PV window can result in considerable energy saving if the office has a relatively large window-to-wall ratio (i.e. ≥ 45%), while the position of placing STPV glazing has significant influence on the lighting energy consumption. In the specific climates under test, the optimal design scenario of applying window integrated PV can result in a reduction in energy consumption of up to 73%. The simulation results also show that this PV window offers better daylight performance than conventional double glazing and effectively reduces the possibility of glare.
Abstract.
Shanks K, Baig H, Singh NP, Senthilarasu S, Reddy KS, Mallick TK (2017). Prototype fabrication and experimental investigation of a conjugate refractive reflective homogeniser in a cassegrain concentrator.
Solar Energy,
142, 97-108.
Abstract:
Prototype fabrication and experimental investigation of a conjugate refractive reflective homogeniser in a cassegrain concentrator
The conjugate refractive reflective homogeniser (CRRH) is experimentally tested within a cassegrain concentrator of geometrical concentration ratio 500× and its power output compared to the theoretical predictions of a 7.76% increase. I–V traces are taken at various angles of incidence and experimental results showed a maximum of 4.5% increase in power output using the CRRH instead of its purely refractive counterpart. The CRRH utilises both total internal reflection (TIR) within its core refractive medium (sylguard) and an outer reflective film (with an air gap between) to direct more rays towards the receiver. The reflective film captures scattered refracted light which is caused by non-ideal surface finishes of the refractive medium. The CRRH prototype utilises a 3D printed support which is thermally tested, withstanding temperatures of up to 60 °C but deforming at >100 °C. A maximum temperature of 226.3 °C was reached within the closed system at the focal spot of the concentrated light. The material properties are presented, in particular the transmittance of sylguard 184 is shown to be dependent on thickness but not significantly on temperature. Utilising both TIR and standard reflection can be applied to other geometries other than the homogeniser presented here. This could be a simple but effective method to increase the power of many concentrator photovoltaics.
Abstract.
Shanks K, Senthilarasu S, Mallick TK (2016). Optics for concentrating photovoltaics: Trends, limits and opportunities for materials and design. Renewable and Sustainable Energy Reviews, 60, 394-407.
Shanks K, Sarmah N, Ferrer-Rodriguez JP, Senthilarasu S, Reddy KS, Fernández EF, Mallick TK (2016). Theoretical Investigation Considering Manufacturing Errors of a High Concentrating Photovoltaic of Cassegrain design and it’s Experimental Validation.
Solar Energy,
131, 235-245.
Abstract:
Theoretical Investigation Considering Manufacturing Errors of a High Concentrating Photovoltaic of Cassegrain design and it’s Experimental Validation
A compact high concentrating photovoltaic module based on cassegrain optics is presented; consisting of a primary parabolic reflector, secondary inverse parabolic reflector and a third stage homogeniser. The effect of parabolic curvatures, reflector separation distance and the homogeniser’s height and width on the acceptance angle has been investigated for optimization. Simulated optical efficiencies of 84.82 – 81.89 % over a range of ±1 degree tracking error and 55.49% at a tracking error of ±1.5 degrees were obtained. The final singular module measures 169mm in height and 230mm in width (not including structural components such as cover glass).The primary reflector dish has a focal length of 200mm and is afocal with the secondary inverse reflector which has a focal length of 70mm. The transparent homogenising optic has a height of 70mm, an entry aperture of 30 x 30mm and an output aperture of 10 x 10mm to match the solar cell. This study includes an analysis of the optical efficiency, acceptance angle, irradiance distribution and component errors for this type of concentrator. In particular material stability and the surface error of the homogeniser proved to be detrimental in theoretical and experimental testing – reducing the optical efficiency to ~40%. This study proves the importance of material choice and simulating optical surface quality, not simply assuming ideal conditions. In the experimental testing, the acceptance angle followed simulation results as did the optical efficiency of the primary and secondary reflectors. The optical efficiency of the system against increasing solar misalignment angles is given for the theoretical and experimental work carried out.
Abstract.
Shanks K, Senthilarasu S, Mallick TK (2015). High-concentration optics for photovoltaic applications.
Green Energy and Technology,
190, 85-113.
Abstract:
High-concentration optics for photovoltaic applications
The concept of a high-concentration optical system is introduced detailing the various design types and focusing only on those aimed at photovoltaic (PV) applications. This will include point focus, line focus, imaging, nonimaging, and the classical cassegrain set-up. The theory of high-concentration optics is explained in terms of idealised concepts and maximum limits for each concentrator type and combination. The optical system is broken down into the different stages and materials possible in a high-concentration configuration. The physics of reflective and refractive optics are described, and their associated errors, advantages and a brief overview of past milestones, and recent research trends in the area of high-concentration PVs are presented. Current primary and secondary optics are geometrically explained covering Fresnel, parabolic, heliostat, compound parabolic, hyperboloid, v-trough, and dome-shaped optics. This chapter also covers examples of new secondary optics, such as the three-dimensional crossed-compound parabolic concentrator and the square elliptical hyperboloid concentrator. The aim of this chapter is to provide the basic optical behaviour of high-concentration designs aimed at PV applications considering their geometry, materials, and reliability.
Abstract.
Ffrench-Constant RH (2015). White butterflies as solar photovoltaic concentrators. Scientific Reports, 5
Chapters
Sundaram S, Shanks K, Upadhyaya H (2018). 18 Thin Film Photovoltaics. In (Ed) A Comprehensive Guide to Solar Energy Systems, 361-370.
Conferences
Ahmed A, Alzahrani M, Shanks K, Sundaram S, Mallick TK (2022). Reliability and temperature limits of the focal spot of a primary optical component for an ultra-high concentrated photovoltaic system. 17TH INTERNATIONAL CONFERENCE ON CONCENTRATOR PHOTOVOLTAIC SYSTEMS (CPV-17).
Shanks K, Ffrench-Constant R (2022). Understanding the anti-reflective glasswing butterfly for enhanced solar concentrator optics. Light in Nature IX.
Sun Y, Shanks K, Baig H, Zhang W, Hao X, Li Y, He B, Wilson R, Liu H, Sundaram S, et al (2019). Integrated CdTe PV glazing into windows: Energy and daylight performance for different window-to-wall ratio.
Abstract:
Integrated CdTe PV glazing into windows: Energy and daylight performance for different window-to-wall ratio
Abstract.
Shanks K, Knowles A, Brierly A, Baig H, Sun Y, Wu Y, Mallick T (2019). Prototype optical modelling procedure and outdoor characterization of an embedded polyolefin crossed compound parabolic concentrator for integrated photovoltaic windows.
Abstract:
Prototype optical modelling procedure and outdoor characterization of an embedded polyolefin crossed compound parabolic concentrator for integrated photovoltaic windows
Abstract.
Shanks K, Baig H, Knowles A, Brierley A, Orr H, Patel J, Foster N, Ball S, Sun Y, Wu Y, et al (2019). The Assembly of Embedded Systems for Integrated Photovoltaic windows in Rural Buildings (E-IPB).
Abstract:
The Assembly of Embedded Systems for Integrated Photovoltaic windows in Rural Buildings (E-IPB)
Abstract.
Shanks K, Senthilarasu S, Mallick T (2017). Reliability investigation for a built ultrahigh concentrator prototype.
Abstract:
Reliability investigation for a built ultrahigh concentrator prototype
Abstract.
Siyabi IA, Shanks K, Mallick T, Sundaram S (2017). Thermal analysis of a multi-layer microchannel heat sink for cooling concentrator photovoltaic (CPV) cells.
Abstract:
Thermal analysis of a multi-layer microchannel heat sink for cooling concentrator photovoltaic (CPV) cells
Abstract.
Mallick TK, Micheli L, Banerjee S, Shanks K, Lokeswaran S, Baig H, Calabria F, Sarmah N, Walker M, Theristis M, et al (2015). Status and perspective of concentrating photovoltaic systems: the results of the BioCPV project and opportunities for a sustainable energy supply to rural areas.
Abstract:
Status and perspective of concentrating photovoltaic systems: the results of the BioCPV project and opportunities for a sustainable energy supply to rural areas
Abstract.
Shanks K, Baig H, Mallick TK (2015). The Conjugate Refractive-Reflective Homogeniser in a 500x Cassegrain Concentrator: Design and Limits. PVSAT-11. 15th - 17th Apr 2015.
Perez-Higueras P, Pablo Ferrer-Rodriguez J, Shanks K, Almonacid F, Fernandez EF (2015). Thin Photovoltaic Modules at Ultra High Concentration.
Author URL.
Shanks K, Sarmah N, Reddy KS, Mallick T (2014). The Design of a Parabolic Reflector System with High Tracking Tolerance for High Solar Concentration.
Author URL.
Publications by year
2023
Cameron WJ, Alzahrani MM, Yule J, Shanks K, Reddy KS, Mallick TK (2023). Indoor experimental analysis of Serpentine-Based cooling scheme for high concentration photovoltaic thermal systems. Applied Thermal Engineering, 234, 121183-121183.
Motamedi M, Jia G, Yao Y, Shanks K, Yousefi P, Hewakuruppu YL, Rafeie M, Lindner F, Patterson R, Christiansen S, et al (2023). Nanopatterned indium tin oxide as a selective coating for solar thermal applications.
Renewable Energy,
210, 386-396.
Abstract:
Nanopatterned indium tin oxide as a selective coating for solar thermal applications
Indium tin oxide (ITO) coatings have been proposed to reduce thermal emission losses for solar thermal applications. Unfortunately, ITO also has a large amount of free charge carriers (∼1 × 1020 per cm3), which absorb sunlight. To address this issue, we propose a nano-patterned ITO-coated quartz exhibiting both anti-reflectivity (to maximize solar transmission) and low emissivity (to minimize long wavelengths radiative losses). A record small-size nanosphere (∼60 nm) etch mask was prepared via double self-assembly, followed by dry etching and characterisation. In parallel, alternative nanopattern geometries were modelled using the Lumerical FDTD software to optimise short wavelength transmission without diminishing the inherently low emissivity of unetched ITO. It was found that an inverted moth's eye pattern (height = 250 nm and spacing = 80 nm) gave the best results at various solar concentrations (1 sun @ 100 °C, 10 suns @ 400 °C, and 100 suns @ 600 °C), resulting in ∼7% improvement in the solar weighted transmission as well as a similar boost in the overall efficiency factor for selectivity. It was concluded that if the proposed deposition/etching processes can be cost-effectively scaled in a continuous process, it would provide a net performance boost for most solar thermal technologies.
Abstract.
Cameron WJ, Alzahrani MM, Yule J, Shanks K, Reddy KS, Mallick TK (2023). Outdoor experimental validation for ultra-high concentrator photovoltaic with serpentine-based cooling system. Renewable Energy, 215, 118926-118926.
2022
Zhang W, Li J, Xie L, Hao X, Mallick T, Wu Y, Baig H, Shanks K, Sun Y, Yan X, et al (2022). Comprehensive analysis of electrical-optical performance and application potential for 3D concentrating photovoltaic window. Renewable Energy, 189, 369-382.
Cameron WJ, Alzahrani MM, Yule J, Shanks K, Reddy KS, Mallick T (2022). Indoor Experimental Analysis of Serpentine-Based Cooling Scheme for High Concentration Photovoltaic Thermal Systems.
Ahmed A, Alzahrani M, Shanks K, Sundaram S, Mallick TK (2022). Reliability and temperature limits of the focal spot of a primary optical component for an ultra-high concentrated photovoltaic system. 17TH INTERNATIONAL CONFERENCE ON CONCENTRATOR PHOTOVOLTAIC SYSTEMS (CPV-17).
Shanks K, Ffrench-Constant R (2022). Understanding the anti-reflective glasswing butterfly for enhanced solar concentrator optics. Light in Nature IX.
2021
Li Q, Zhuo Y, Shanks K, Taylor RA, Conneely B, Tan A, Shen Y, Scott J (2021). A winged solar biomass reactor for producing 5-hydroxymethylfurfural (5-HMF).
Solar Energy,
218, 455-468.
Abstract:
A winged solar biomass reactor for producing 5-hydroxymethylfurfural (5-HMF)
Biomass-derived alcohols such as 5-Hydroxymethylfurfural represent a promising intermediary energy and species carriers for hydrogen and value‐added chemical production. Solar-driven reforming of biomass to 5-HMF at the desired reaction condition (e.g. at ~150 °C and ~5 bars) offers a sustainable route, but the lack of a rooftop-based solar biomass reactor represents a substantial impediment. In this work, a unique, low-profile “winged” solar concentrator with an evacuated tube reactor was designed for the renewable production of 5-HMF. The viability of this design was examined in detail, using sucrose as the feedstock for 5-HMF production in the presence of sulfuric acid. The optical study indicated that the winged structure significantly increased the effective concentration ratio (by ~42%) and that the design has a broader acceptance angle (from 60° to 90°) compared to CPC alone. During outdoor experiments, the wings boosted the thermal efficiency from 18% to ~25% when operating at 150 °C, and achieved a maximum 5-HMF yield of ~21 mol % (under a solar irradiance of ~800 W/m2). In parallel, a transient computational fluid dynamics model was developed to further elucidate the heat and mass transfer phenomena inside the reactor and to investigate a broader range of operating conditions and reactor design parameters. The numerical and experimental results were in agreement that a specific energy consumption for 5-HMF production of ~23 kWh/kg was achievable and that a full-scale system (~3 L reactor volume, 2.1 m2 gross area) can produce ~0.45 kg of 5-HMF per day, with an average daily solar input of 5 kWh/m2.
Abstract.
Alzahrani M, Shanks K, Mallick TK (2021). Advances and limitations of increasing solar irradiance for concentrating photovoltaics thermal system.
Renewable and Sustainable Energy Reviews,
138Abstract:
Advances and limitations of increasing solar irradiance for concentrating photovoltaics thermal system
Concentrating photovoltaic-thermal (CPVT) technology harnesses solar energy by increasing the solar density upon cells using optical concentrators. CPVT systems are the focus of ongoing research and improvements to achieve the highest potential for energy harnessing and utilization. Increasing the concentration ratio for high energy generation raises many advances and limitations in the CPVT design. This article highlights the influence of the temperature with an increasing concentration ratio on CPVT components in terms of single-/multi-junction semiconductor materials, primary and secondary optical concentrator materials, and thermal receiver design. To achieve this, the theory of single- and multi-junction solar cell electrical characteristics (Voc,Isc,FF and η) is first explained to understand their dependence on the temperature and concentration ratio. An extensive literature review discussing the advantages, disadvantages, and potential of current CPVT research is given. This includes graphical and tabular summaries of many of the various CPVT design performances. In this review, it has been ascertained that higher concentration ratios raise the temperature at which the performance, operation and reliability of CPVT system are affected. Also, this review indicates that the temperature elevation of the CPVT components is significantly impacted by the optical configuration and their material types and reflectance. A thermal receiver is illustrated as three components: solar cell (heat source), heat spreader (substrates) and its different types, and cooling mechanism. In addition, the article addresses the thermomechanical stress created with intensified illumination, especially with secondary optics, where the optical materials and optical tolerance need to be carefully explored. The economic implications of a high concentration ratio level are briefly considered, addressing the reduction in system cost by enhancing the system efficiency. Suggestions are made throughout the review as to possible improvements in system performance.
Abstract.
Ahmed A, Shanks K, Sundaram S, Mallick T (2021). Energy and exergy analyses of new cooling schemes based on a serpentine configuration for a high concentrator photovoltaic system.
Applied Thermal Engineering,
199Abstract:
Energy and exergy analyses of new cooling schemes based on a serpentine configuration for a high concentrator photovoltaic system
High concentrator photovoltaic is expected to play an increasingly important role in electrical energy production. Controlling multijunction solar cell temperature within the recommended conditions is a key challenge that limits the functionality of this growing technology making the identification of an efficient cooling method an essential requirement. Hence, in this research, new heat sink configurations based on a serpentine design are studied and compared with the straight channel arrangement. To assess the performance of the high concentrator photovoltaic, a 3D model is built for the multijunction cell and heat sink and impact of the heat sink configuration, mass flow rate, and concentration ratio are investigated. The results include solar cell temperature distribution, thermal resistance, pumping power, thermal and electrical energy and exergy efficiencies. The study shows that the straight channel is not recommended for concentration above 1000×, whereas the centre inlet serpentine design can maintain a uniform temperature distribution for the system for concentration up to 2000×. Temperature non-uniformity varies between 18 °C and 5 °C. The highest overall energy and exergy efficiencies reached 78% and 35.2% respectively at concentration of 2000×. The results prove the effectiveness of implementing a serpentine design as a new cooling scheme for the system.
Abstract.
Li J, Zhang W, He B, Xie L, Hao X, Mallick T, Shanks K, Chen M, Li Z (2021). Experimental study on the comprehensive performance of building curtain wall integrated compound parabolic concentrating photovoltaic.
Energy,
227Abstract:
Experimental study on the comprehensive performance of building curtain wall integrated compound parabolic concentrating photovoltaic
A novel concentrating photovoltaic curtain wall (CPV-CW) system integrated with building has been designed, tested and analyzed, and its application potential is determined and improvement suggestions are proposed. It can effectively improve the efficiency of photovoltaic (PV) module and provide a more uniform indoor lighting environment. The concentrator is constructed with truncated stationary asymmetric compound paraboloid. and cyclic olefin copolymer (COC) with high transmittance is selected as its structural material. A model building combined with CPV-CW system curtain wall has been designed and applied to the outdoor experiments. It was tested on its electricity generation efficiency, the internal lighting environment, and thermal insulation ability. According to the real time results, under the clear weather conditions, the transmittance of the CPV-CW system reaches 9.1%. The highest CPV-CW system generation efficiency, 26.5%, could be found in winter, followed by the autumn and summer separately. In addition, CPV-CW system can create a more uniform indoor light environment and meet the requirements of building insulation. Based on the analysis, the CPV-CW system has a broad application prospect for building integrated with concentrating photovoltaic.
Abstract.
Alzahrani M, Roy A, Shanks K, Sundaram S, Mallick TK (2021). Graphene as a pre-illumination cooling approach for a concentrator photovoltaic (CPV) system. Solar Energy Materials and Solar Cells, 222, 110922-110922.
Pickering T, Shanks K, Sundaram S (2021). Modelling technique and analysis of porous anti-reflective coatings for reducing wide angle reflectance of thin-film solar cells.
Journal of Optics,
23(2), 025901-025901.
Abstract:
Modelling technique and analysis of porous anti-reflective coatings for reducing wide angle reflectance of thin-film solar cells
Abstract
. Bio-inspired anti-reflective (AR) coatings with porous graded refractive index structures are known to considerably reduce the reflectance of light at optical interfaces, however, research is lacking for thin-film cell application. Ray Tracing software coupled with the Effective Medium Theory were used to simulate the reflectance of nanostructured coatings placed above a thin-film system. The most optimal coating was paraboloid-shaped, with 300 nm nipple heights and spacings of 15%. The non-zero refractive index ‘step’ aids light trapping and energy absorption. This coating reduced reflectance in the λ = 300–800 nm range by an average of 2.665% and 11.36% at 0∘ and 80∘ incident light, respectively, whilst increasing annual energy output by 4.39% and 5.39% for standard UK roof and vertical window tilts, respectively. Significant wide angle reflectance capabilities are demonstrated at specifically λ = 300 nm and 80∘ incident light, with a reflectance reduction of 19.192%. There are now many promising manufacturing techniques for these porous nanostructures, such as AR or wavelength filtering coatings for photovoltaics. Further understanding of the exact parameters needed to replicate these nanostructures must be explored to proceed.
Abstract.
Alzahrani M, Ahmed A, Shanks K, Sundaram S, Mallick T (2021). Optical component analysis for ultrahigh concentrated photovoltaic system (UHCPV). Solar Energy, 227, 321-333.
Ahmed A, Zhang G, Shanks K, Sundaram S, Ding Y, Mallick T (2021). Performance evaluation of single multi-junction solar cell for high concentrator photovoltaics using minichannel heat sink with nanofluids.
Applied Thermal Engineering,
182Abstract:
Performance evaluation of single multi-junction solar cell for high concentrator photovoltaics using minichannel heat sink with nanofluids
High concentrated photovoltaic systems (HCPV) have demonstrated the potential to achieve high conversion power over conventional photovoltaic panels (PV) especially for areas with high solar irradiance. However, the multi-junction (MJ) solar cells may be subjected to damage if the temperature exceeds 110 °C as recommended by the manufacturer. Hence, in this paper, the overall performance of a 1cm2 MJ solar cell with a mini-channel heat sink subjected to high concentration ratio (500×to2000×) is investigated to find improved method of reducing the cell temperature. The impact of using water, Al2O3/water, and SiO2/water on the effectiveness of heat transfer, temperature distribution on the MJ solar cell, and performance evaluation criteria are studied. Also, the evaluation of the HCPVT system performance is presented. A 3D computational modelling is performed and the experimental measurements for the thermal conductivity are constructed for the different fluids and entered in the simulation. Nanofluids maintain the maximum solar cell temperature at 95.25 °C and 67.1 °C at Reynolds number (Re) of 8.25 and 82.5 respectively and a concentration ratio of 2000×. The overall efficiency of the system increases by 3.82% at Re of 8.25 and a concentration ratio of 500× by using SiO2/water at 5%.
Abstract.
Khalid M, Shanks K, Ghosh A, Tahir A, Sundaram S, Mallick TK (2021). Temperature regulation of concentrating photovoltaic window using argon gas and polymer dispersed liquid crystal films.
Renewable Energy,
164, 96-108.
Abstract:
Temperature regulation of concentrating photovoltaic window using argon gas and polymer dispersed liquid crystal films
Low concentrating photovoltaic (LCPV) system has been studied extensively, which showed excellent potential for the building integration application. However, such a system suffers from higher operating temperatures due to the concentrated light exposed into the solar cell. In this work, two different methods have been used to regulate the operating temperature of the solar cell without the interference of any other external mechanism. Two concepts were used to study the operating temperature of the solar cells are: i) use of Argon gas within the concentrator element, ii) incorporation of polymer-dispersed liquid crystal films (PDLC) on top of the module. In both cases, the power was improved by 37 mW–47 mW when temperature was reduced by 10 °C and 4 °C for the Argon gas-filled module and PDLC integrated module, respectively. In addition, the temperature effect of the PDLC integrated module showed a unique nature of reduction of the short circuit current due to the orientation of the liquid crystal particle, which increased at a higher temperature. The current study, therefore, shows the greater potential of improving the operating efficiency and reduction of solar cell temperature, without the need for additional pumping power such as needed for photovoltaic thermal application.
Abstract.
2020
Sun Y, Liu D, Flor JF, Shank K, Baig H, Wilson R, Liu H, Sundaram S, Mallick TK, Wu Y, et al (2020). Analysis of the daylight performance of window integrated photovoltaics systems.
Renewable Energy,
145, 153-163.
Abstract:
Analysis of the daylight performance of window integrated photovoltaics systems
Integrating photovoltaics into windows provides the possibility of including an additional function of energy production to a conventional building fenestration component. There is no doubt that electrical power can be generated on-site. However, the effect of PV windows on the indoor luminous environment of the space served by them has not been comprehensively researched. This paper investigated the daylight performance of integrating four types of photovoltaics (semi-transparent thin film Cadmium telluride (CdTe) solar cells with 10% and 50% transparency, crystalline silicon solar cells with and without crossed compound parabolic concentrators (CCPC)) to a window of a typical south-facing office under different Window-to-Wall Ratios (WWRs). Annual useful daylight illuminance (UDI), daylight uniformity ratio (UR) and daylight glare probability (DGP) have been analysed based on dynamic simulation using RADIANCE. The simulation results show that windows integrated with crystalline silicon cells and CCPC optics have the potential to provide best daylight availability when compared with standard double glazed windows and other tested PV window prototypes, if it is applied to rooms with large WWRs (e.g. 60% or 75% WWR) at high latitudes (e.g. city of Harbin). Its application also improves the uniformity of daylight spatial distribution and eliminates the risk of glare. Semi-transparent CdTe PV window with 10% transparency can also improve the percentage of working hours that fall into UDI 500–2000lux range, however, it will result in the most sharp illuminance contrasts within the room. Applying all of these tested PV windows can effectively reduce the possibility of glare.
Abstract.
Gadkari D, Shanks KS, Philipp HT, Tate MW, Thom-Levy J, Gruner SM (2020). Characterization of an architecture for front-end pixel binning in an integrating pixel array detector. Journal of Instrumentation, 15(11), T11002-T11002.
Ahmed A, Alzahrani M, Shanks K, Sundaram S, Mallick TK (2020). Effect of using an infrared filter on the performance of a silicon solar cell for an ultra-high concentrator photovoltaic system.
Materials Letters,
277Abstract:
Effect of using an infrared filter on the performance of a silicon solar cell for an ultra-high concentrator photovoltaic system
It is well known that increasing the concentration ratio of concentrator photovoltaics has a positive impact on the power output of the system but can reduce the solar cells performance due to the heightened temperatures. In this paper, we introduce the impact of using an infrared (IR) filter on the performance of a silicon solar cell as a preliminary investigation for an ultra-high concentrator photovoltaic system. The investigation is carried out in terms of the optical characterization of the Fresnel lens and the IR filter. Besides, the performance of the system has been introduced in this paper. The results show that although the IR filter protects the solar cell from damage near the tabbing wire, it reduces the experimental power output of the cell by 46.08% due to the low transmittance of the filter while the cell efficiency increased by 183.3%.
Abstract.
Alzahrani M, Baig H, Shanks K, Mallick T (2020). Estimation of the performance limits of a concentrator solar cell coupled with a micro heat sink based on a finite element simulation. Applied Thermal Engineering, 176, 115315-115315.
Al Siyabi I, Shanks K, Mallick T, Sundaram S (2020). Indoor and outdoor characterization of concentrating photovoltaic attached to multi-layered microchannel heat sink. Solar Energy, 202, 55-72.
Alzahrani M, Ahmed A, Shanks K, Sundaram S, Mallick T (2020). Optical losses and durability of flawed Fresnel lenses for concentrated photovoltaic application. Materials Letters, 275, 128145-128145.
Ahmed A, Shanks K, Sundaram S, Mallick TK (2020). Theoretical Investigation of the Temperature Limits of an Actively Cooled High Concentration Photovoltaic System.
Energies,
13(8), 1902-1902.
Abstract:
Theoretical Investigation of the Temperature Limits of an Actively Cooled High Concentration Photovoltaic System
Concentrator photovoltaics have several advantages over flat plate systems. However, the increase in solar concentration usually leads to an increase in the solar cell temperature, which decreases the performance of the system. Therefore, in this paper, we investigate the performance and temperature limits of a high concentration photovoltaic Thermal system (HCPVT) based on a 1 cm2 multi-junction solar cell subjected to a concentration ratio from 500× to 2000× by using three different types of cooling fluids (water, ethylene glycol and water mixture (60:40), and syltherm oil 800). The results show that, for this configuration, the maximum volumetric temperature of the solar cell did not exceed the manufacturer’s recommended limit for the tested fluids. At 2000× the lowest solar cell temperature obtained by using water was 93.5 °C, while it reached as high as 109 °C by using syltherm oil 800, which is almost equal to the maximum operating limit provided by the manufacturer (110 °C). Overall, the best performance in terms of temperature distribution, thermal, and electrical efficiency was achieved by using water, while the highest outlet temperature was obtained by using syltherm oil 800.
Abstract.
2019
Shanks K, Knowles A, Brierley A, Baig H, Orr H, Sun Y, Wu Y, Sundaram S, Mallick T (2019). An experimental analysis of the optical, thermal and power to weight performance of plastic and glass optics with AR coatings for embedded CPV windows.
Solar Energy Materials and Solar Cells,
200Abstract:
An experimental analysis of the optical, thermal and power to weight performance of plastic and glass optics with AR coatings for embedded CPV windows
A low concentrator photovoltaic is presented and the optical losses within a double glazed window assembly are described. The use of plastic instead of glass is analyzed for its reduced weight and hence greater power to weight ratios. Although the transmittance of glass is higher, the power to weight ratio of the plastic devices was almost double that of the glass counterparts and even higher than the original non concentrating silicon cell. The plastic Topas material was found to be the best performing material overall. Crystal Clear, a plastic resin, had a higher average transmittance but had a lower optical efficiency due to the cold cast manufacturing process in comparison to injection moulding of the other materials. This proves the importance of considering both the materials and their associated manufacturing quality. External quantum efficiencies, optical properties, silicon cell temperatures and performance is analyzed for concentrating photovoltaic devices made of varying optical materials. The measurement methods for optical analysis are given in an attempt to separate the optical losses experimentally. The Silicon cells were found to gain higher temperatures due to the insulating plastic optics in comparison to glass but these effects are eliminated during vertical window orientation where instead the encapsulate dominates the insulation of the cell. The results presented here prove plastic optics to be a worthwhile alternative to glass for use in low concentration photovoltaic systems and have the significant effect of reversing the weight disadvantage concentrator photovoltaic technology has compared to standard flat plate solar panels.
Abstract.
Al Siyabi I, Shanks K, Khanna S, Mallick TK, Sundaram S (2019). Evaluation of concentrating photovoltaic performance under different homogeniser materials.
Materials Letters,
241, 219-222.
Abstract:
Evaluation of concentrating photovoltaic performance under different homogeniser materials
In concentrating photovoltaic (CPV), increasing the incoming sunlight to the solar cell influences the performance of the solar cells. The optical efficiency of the CPV components is a key factor to improve the electrical efficiency. Two types of homogeniser materials (K9 glass and crystal resin) were investigated in the CPV application. The results show a higher power generation of the CPV module when using K9 glass homogeniser compared to the crystal resin homogeniser by 27% due to the high transmittance value of the K9 glass material. In addition, the K9 glass material shows an excellent resistance to the heat produced by the concentrated sunlight compared to the crystal resin material.
Abstract.
Sun Y, Shanks K, Baig H, Zhang W, Hao X, Li Y, He B, Wilson R, Liu H, Sundaram S, et al (2019). Integrated CdTe PV glazing into windows: Energy and daylight performance for different window-to-wall ratio.
Abstract:
Integrated CdTe PV glazing into windows: Energy and daylight performance for different window-to-wall ratio
Abstract.
Spalding A, Shanks K, Bennie J, Potter U, Ffrench-Constant R (2019). Optical Modelling and Phylogenetic Analysis Provide Clues to the Likely Function of Corneal Nipple Arrays in Butterflies and Moths.
Insects,
10(9).
Abstract:
Optical Modelling and Phylogenetic Analysis Provide Clues to the Likely Function of Corneal Nipple Arrays in Butterflies and Moths.
The lenses in compound eyes of butterflies and moths contain an array of nipple-shaped protuberances, or corneal nipples. Previous work has suggested that these nipples increase light transmittance and reduce the eye glare of moths that are inactive during the day. This work builds on but goes further than earlier analyses suggesting a functional role for these structures including, for the first time, an explanation of why moths are attracted to UV light. Using a phylogenetic approach and 3D optical modelling, we show empirically that these arrays have been independently lost from different groups of moths and butterflies and vary within families. We find differences in the shape of nipples between nocturnal and diurnal species, and that anti-glow reflectance levels are different at different wave-lengths, a result thereby contradicting the currently accepted theory of eye glow for predator avoidance. We find that there is reduced reflectance, and hence greater photon absorption, at UV light, which is probably a reason why moths are attracted to UV. We note that the effective refractive index at the end of the nipples is very close to the refractive index of water, allowing almost all the species with nipples to see without distortion when the eye is partially or completely wet and providing the potential to keep eyes dry. These observations provide a functional explanation for these arrays. of special interest is the finding that their repeated and independent loss across lepidopteran phylogeny is inconsistent with the explanation that they are being lost in the 'higher', more active butterflies.
Abstract.
Author URL.
Shanks K, Knowles A, Brierly A, Baig H, Sun Y, Wu Y, Mallick T (2019). Prototype optical modelling procedure and outdoor characterization of an embedded polyolefin crossed compound parabolic concentrator for integrated photovoltaic windows.
Abstract:
Prototype optical modelling procedure and outdoor characterization of an embedded polyolefin crossed compound parabolic concentrator for integrated photovoltaic windows
Abstract.
Shanks K, Baig H, Knowles A, Brierley A, Orr H, Patel J, Foster N, Ball S, Sun Y, Wu Y, et al (2019). The Assembly of Embedded Systems for Integrated Photovoltaic windows in Rural Buildings (E-IPB).
Abstract:
The Assembly of Embedded Systems for Integrated Photovoltaic windows in Rural Buildings (E-IPB)
Abstract.
2018
Sundaram S, Shanks K, Upadhyaya H (2018). 18 Thin Film Photovoltaics. In (Ed) A Comprehensive Guide to Solar Energy Systems, 361-370.
Shanks K, Ferrer-Rodriguez JP, Fernàndez EF, Almonacid F, Pérez-Higueras P, Senthilarasu S, Mallick T (2018). A >3000 suns high concentrator photovoltaic design based on multiple Fresnel lens primaries focusing to one central solar cell.
Solar Energy,
169, 457-467.
Abstract:
A >3000 suns high concentrator photovoltaic design based on multiple Fresnel lens primaries focusing to one central solar cell
A high concentrator photovoltaic design is proposed of 5800x geometrical concentration ratio based on multiple primary Fresnel lenses focusing to one central solar cell. The final stage optic is of a novel design, made of a high refractive index (n = ∼1.76), to accept light from four different directions but very easily manufactured. The high geometrical concentration of 5800x was chosen in anticipation of the losses accompanied due to alignment difficulties. Two scenarios are however simulated, one with state of the art optics (achromatic Fresnel lenses and 98% reflective mirrors) and one of standard, relatively cheap optics. An optical efficiency of ∼75% is achieved in simulations if high quality optics are utilised, which gives an optical concentration ratio of just over 4300x. Simulating standard optical constraints with less accurate optics results in an optical efficiency of ∼55% which translates to an optical concentration ratio of ∼3000x. In this way the quality of the optics can be chosen depending on the trade of between cost and efficiency with room for future advanced optics to be incorporated at a later date. The optical efficiency of each component is simulated as well as experimentally measured to ensure the accuracy of the simulations. A theoretical acceptance angle of 0.4° was achieved in ray trace simulations for this design which is considered good for such a high concentration level. The need for achromatic Fresnel lenses is apparent from this study to reach optimum performance and concentration but even 55% optical efficiency results in a >3000x concentration not yet experimentally tested. The solar cells irradiance distribution of the design is also presented along with performance and rough cost comparisons to other systems in the literature. The cost of the optics compared to more complex shaped optics is also given.
Abstract.
Sun Y, Shanks K, Baig H, Zhang W, Hao X, Li Y, He B, Wilson R, Liu H, Sundaram S, et al (2018). Integrated semi-transparent cadmium telluride photovoltaic glazing into windows: Energy and daylight performance for different architecture designs.
Applied Energy,
231, 972-984.
Abstract:
Integrated semi-transparent cadmium telluride photovoltaic glazing into windows: Energy and daylight performance for different architecture designs
When integrating photovoltaics into building windows, the photovoltaic glazing modules inhibit the function that glass performs, with the additional function of energy production. Semi-transparent Photovoltaic (STPV) glazing will absorb part of the solar radiation incident on the window surface to generate electrical power. In turn, this affects the overall solar energy and natural daylight penetrating into the indoor space. Various factors determine the building energy performance and indoor comfort level as a result of adopting STPV glazing. The factors regarding window design alone (window size, PV glazing coverage ratio and PV glazing placing position) require rigorous study. In this paper, an innovate model (combined optical, electrical and energy model) was developed to comprehensively evaluate the performance of an office equipped with STPV window and firstly analyse the effect of window design on overall energy efficiency. A double-glazing unit integrated with thin film CdTe solar cells with 10% transparency was electrically characterised by Sandia Array Performance Model (SAPM). The annual energy performance of a typical office served by window integrated STPV glazing was investigated through EnergyPlus simulation for various window designs under five typical climatic conditions in China (using weather files of Harbin, Beijing, Shanghai, Guangzhou and Kunming for representation). The optical performance (defined by a Bidirectional Scattering Distribution Function) of this STPV glazing was also obtained using a ray-tracing technique. Then, the annual daylight performance of the porotype office was assessed using RADIANCE. We found that when compared to a conventional double-glazed system, the application of PV window can result in considerable energy saving if the office has a relatively large window-to-wall ratio (i.e. ≥ 45%), while the position of placing STPV glazing has significant influence on the lighting energy consumption. In the specific climates under test, the optimal design scenario of applying window integrated PV can result in a reduction in energy consumption of up to 73%. The simulation results also show that this PV window offers better daylight performance than conventional double glazing and effectively reduces the possibility of glare.
Abstract.
2017
Shanks K, Baig H, Singh NP, Senthilarasu S, Reddy KS, Mallick TK (2017). Prototype fabrication and experimental investigation of a conjugate refractive reflective homogeniser in a cassegrain concentrator.
Solar Energy,
142, 97-108.
Abstract:
Prototype fabrication and experimental investigation of a conjugate refractive reflective homogeniser in a cassegrain concentrator
The conjugate refractive reflective homogeniser (CRRH) is experimentally tested within a cassegrain concentrator of geometrical concentration ratio 500× and its power output compared to the theoretical predictions of a 7.76% increase. I–V traces are taken at various angles of incidence and experimental results showed a maximum of 4.5% increase in power output using the CRRH instead of its purely refractive counterpart. The CRRH utilises both total internal reflection (TIR) within its core refractive medium (sylguard) and an outer reflective film (with an air gap between) to direct more rays towards the receiver. The reflective film captures scattered refracted light which is caused by non-ideal surface finishes of the refractive medium. The CRRH prototype utilises a 3D printed support which is thermally tested, withstanding temperatures of up to 60 °C but deforming at >100 °C. A maximum temperature of 226.3 °C was reached within the closed system at the focal spot of the concentrated light. The material properties are presented, in particular the transmittance of sylguard 184 is shown to be dependent on thickness but not significantly on temperature. Utilising both TIR and standard reflection can be applied to other geometries other than the homogeniser presented here. This could be a simple but effective method to increase the power of many concentrator photovoltaics.
Abstract.
Shanks K, Senthilarasu S, Mallick T (2017). Reliability investigation for a built ultrahigh concentrator prototype.
Abstract:
Reliability investigation for a built ultrahigh concentrator prototype
Abstract.
Siyabi IA, Shanks K, Mallick T, Sundaram S (2017). Thermal analysis of a multi-layer microchannel heat sink for cooling concentrator photovoltaic (CPV) cells.
Abstract:
Thermal analysis of a multi-layer microchannel heat sink for cooling concentrator photovoltaic (CPV) cells
Abstract.
2016
Shanks K, Senthilarasu S, Mallick TK (2016). Optics for concentrating photovoltaics: Trends, limits and opportunities for materials and design. Renewable and Sustainable Energy Reviews, 60, 394-407.
Shanks K, Sarmah N, Ferrer-Rodriguez JP, Senthilarasu S, Reddy KS, Fernández EF, Mallick TK (2016). Theoretical Investigation Considering Manufacturing Errors of a High Concentrating Photovoltaic of Cassegrain design and it’s Experimental Validation.
Solar Energy,
131, 235-245.
Abstract:
Theoretical Investigation Considering Manufacturing Errors of a High Concentrating Photovoltaic of Cassegrain design and it’s Experimental Validation
A compact high concentrating photovoltaic module based on cassegrain optics is presented; consisting of a primary parabolic reflector, secondary inverse parabolic reflector and a third stage homogeniser. The effect of parabolic curvatures, reflector separation distance and the homogeniser’s height and width on the acceptance angle has been investigated for optimization. Simulated optical efficiencies of 84.82 – 81.89 % over a range of ±1 degree tracking error and 55.49% at a tracking error of ±1.5 degrees were obtained. The final singular module measures 169mm in height and 230mm in width (not including structural components such as cover glass).The primary reflector dish has a focal length of 200mm and is afocal with the secondary inverse reflector which has a focal length of 70mm. The transparent homogenising optic has a height of 70mm, an entry aperture of 30 x 30mm and an output aperture of 10 x 10mm to match the solar cell. This study includes an analysis of the optical efficiency, acceptance angle, irradiance distribution and component errors for this type of concentrator. In particular material stability and the surface error of the homogeniser proved to be detrimental in theoretical and experimental testing – reducing the optical efficiency to ~40%. This study proves the importance of material choice and simulating optical surface quality, not simply assuming ideal conditions. In the experimental testing, the acceptance angle followed simulation results as did the optical efficiency of the primary and secondary reflectors. The optical efficiency of the system against increasing solar misalignment angles is given for the theoretical and experimental work carried out.
Abstract.
2015
Shanks K, Senthilarasu S, Mallick TK (2015). High-concentration optics for photovoltaic applications.
Green Energy and Technology,
190, 85-113.
Abstract:
High-concentration optics for photovoltaic applications
The concept of a high-concentration optical system is introduced detailing the various design types and focusing only on those aimed at photovoltaic (PV) applications. This will include point focus, line focus, imaging, nonimaging, and the classical cassegrain set-up. The theory of high-concentration optics is explained in terms of idealised concepts and maximum limits for each concentrator type and combination. The optical system is broken down into the different stages and materials possible in a high-concentration configuration. The physics of reflective and refractive optics are described, and their associated errors, advantages and a brief overview of past milestones, and recent research trends in the area of high-concentration PVs are presented. Current primary and secondary optics are geometrically explained covering Fresnel, parabolic, heliostat, compound parabolic, hyperboloid, v-trough, and dome-shaped optics. This chapter also covers examples of new secondary optics, such as the three-dimensional crossed-compound parabolic concentrator and the square elliptical hyperboloid concentrator. The aim of this chapter is to provide the basic optical behaviour of high-concentration designs aimed at PV applications considering their geometry, materials, and reliability.
Abstract.
Mallick TK, Micheli L, Banerjee S, Shanks K, Lokeswaran S, Baig H, Calabria F, Sarmah N, Walker M, Theristis M, et al (2015). Status and perspective of concentrating photovoltaic systems: the results of the BioCPV project and opportunities for a sustainable energy supply to rural areas.
Abstract:
Status and perspective of concentrating photovoltaic systems: the results of the BioCPV project and opportunities for a sustainable energy supply to rural areas
Abstract.
Shanks K, Baig H, Mallick TK (2015). The Conjugate Refractive-Reflective Homogeniser in a 500x Cassegrain Concentrator: Design and Limits. PVSAT-11. 15th - 17th Apr 2015.
Perez-Higueras P, Pablo Ferrer-Rodriguez J, Shanks K, Almonacid F, Fernandez EF (2015). Thin Photovoltaic Modules at Ultra High Concentration.
Author URL.
Ffrench-Constant RH (2015). White butterflies as solar photovoltaic concentrators. Scientific Reports, 5
2014
Shanks K, Sarmah N, Reddy KS, Mallick T (2014). The Design of a Parabolic Reflector System with High Tracking Tolerance for High Solar Concentration.
Author URL.
