Sun-tracking optical element realized using thermally activated transparency-switching material

Apostoleris, Harry; Stefancich, Marco; Lilliu, Samuele; Chiesa, Matteo

doi:10.1364/oe.23.00a930

Cited by 10 publications

(3 citation statements)

References 15 publications

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“…In the ideal case, a capture η of 25.7% is obtained. Another type of secondary optics such as a compound parabolic concentrator (CPC) [56], covered with the same switchable material [57,58], has been investigated instead of employing light guides. Theoretically, an η opt of 95% can be achieved with an angular range of ±23 • and an approximate concentration of 31 suns.…”

Section: Hybrid Tracking Systemmentioning

confidence: 99%

Tracking-Integrated CPV Technology: State-of-the-Art and Classification

et al. 2023

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Concentrator photovoltaic (CPV) technology offers an alternative to conventional photovoltaic systems, focusing on the concentration of solar radiation through the optics of the system onto smaller and more efficient solar cells. CPV technology captures direct radiation and requires precise module orientation. Traditional CPV systems use robust and heavy solar trackers to achieve the necessary alignment, but these trackers add to the installation and operating costs. To address this challenge, tracking-integrated CPV systems have been developed, eliminating the need for conventional trackers. These systems incorporate tracking mechanisms into the CPV module itself. This review presents a detailed classification of existing designs in the literature and provides an overview of this type of system with different approaches to integrated tracking including tracking concentrator elements, using external trackers, or employing internal trackers (the most researched). These approaches enable the automatic adjustment of the CPV system components to follow the movement of the Sun. The various tracking-integrated systems have different designs and performance characteristics. Significant progress has been made in developing tracking-integrated CPV systems with the aim to make CPV technology more competitive and expand its applications in markets where traditional CPV has been excluded.

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Section: Hybrid Tracking Systemmentioning

confidence: 99%

Tracking-Integrated CPV Technology: State-of-the-Art and Classification

et al. 2023

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“…Various tracking integration schemes have been proposed and demonstrated for over a decade [19][20][21][22][23][24][25], mostly on experimental scales but with some recent commercial activity.…”

Section: Micro-concentrators and Micro-trackingmentioning

confidence: 99%

The CPV “Toolbox”: New Approaches to Maximizing Solar Resource Utilization with Application-Oriented Concentrator Photovoltaics

2021

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As the scaling of silicon PV cells and module manufacturing has driven solar energy penetration up and costs down, concentrator photovoltaic technologies, originally conceived as a cost-saving measure, have largely been left behind. The loss of market share by CPV is being locked in even as solar energy development encounters significant obstacles related to space constraints in many parts of the world. The inherently higher collection efficiency enabled by the use of concentrators could substantially alleviate these challenges, but the revival of CPV for this purpose requires substantial reinvention of the technology to actually capture the theoretically possible efficiency gains, and to do so at market-friendly costs. This article will discuss recent progress in key areas central to this reinvention, including miniaturization of cells and optics to produce compact, lightweight “micro-CPV” systems; hybridization of CPV with thermal, illumination and other applications to make use of unused energy streams such as diffuse light and waste heat; and the integration of sun-tracking into the CPV module architecture to enable greater light collection and more flexible deployment, including integration into built structures. Applications showing particular promise include thermal applications such as water heating, industrial processes and desalination; agricultural photovoltaics; building-integrated photovoltaics with dynamic daylighting capabilities; and chemical processes including photocatalysis and hydrogen production. By appropriately tailoring systems to the available solar resource and local energy demand, we demonstrate how CPV can finally achieve real-world efficiencies, or solar resource utilization factors, far higher than those of standard silicon-based PV systems. This makes the argument for sustained development of novel CPV designs that can be applied to the real-world settings where this efficiency boost will be most beneficial.

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“…In fact, most works focus on the mechanical and TES properties of the resulting blends, and the leakage of the PCM is prevented with the addition of a micro- or nanofiller or by using a microencapsulated PCM, which causes loss of transparency above the melting temperature of the PCM [ 35 , 36 , 37 ]. Conversely, other authors successfully prepared PCM/PDMS blends with interchangeable transmittance, thus demonstrating the feasibility of this approach [ 38 , 39 , 40 , 41 ]. For example, Shi et al [ 41 ] prepared PDMS/paraffin films with interchangeable transmittance at 60 °C.…”

Section: Introductionmentioning

confidence: 98%

Thermotropic Optical Response of Silicone–Paraffin Flexible Blends

et al. 2022

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Organic phase change materials, e.g., paraffins, are attracting increasing attention in thermal energy storage (TES) and thermal management applications. However, they also manifest interesting optical properties such as thermotropism, as they can switch from optically opaque to transparent reversibly and promptly at the melting temperature. This work aims at exploiting this feature to produce flexible silicone-based blends with thermotropic properties for applications in glazed windows or thermal sensors. Blends are produced by adding paraffin (Tm = 44 °C, up to 10 phr) to a silicone bicomponent mixture, and, for the first time, cetyltrimethylammonium bromide (CTAB) is also added to promote paraffin dispersion and avoid its exudation. CTAB is proven effective in preventing paraffin exudation both in the solid and in the liquid state when added in a fraction above 3 phr with respect to paraffin. Rheological results show that paraffin decreases the complex viscosity, but neither paraffin nor CTAB modifies the curing behavior of silicone, which indicates uniform processability across the investigated compositions. On the other hand, paraffin causes a decrease in the stress and strain at break at 60 °C, and this effect is amplified by CTAB, which acts as a defect and stress concentrator. Conversely, at room temperature, solid paraffin only slightly impairs the mechanical properties, while CTAB increases both the elastic modulus and tensile strength, as also highlighted with ANOVA. Finally, optical transmittance results suggest that the maximum transmittance difference below and above the melting temperature (65–70 percentage points) is reached for paraffin amounts of 3 to 5 phr and a CTAB amount of max. 0.15 phr.

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Sun-tracking optical element realized using thermally activated transparency-switching material

Cited by 10 publications

References 15 publications

Tracking-Integrated CPV Technology: State-of-the-Art and Classification

Tracking-Integrated CPV Technology: State-of-the-Art and Classification

The CPV “Toolbox”: New Approaches to Maximizing Solar Resource Utilization with Application-Oriented Concentrator Photovoltaics

Thermotropic Optical Response of Silicone–Paraffin Flexible Blends

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