Concentrating photovoltaic (CPV) systems are a key step in expanding the use of solar energy. Solar cells can operate at increased efficiencies under higher solar concentration and replacing solar cells with optical devices to capture light is an effective method of decreasing the cost of a system without compromising the amount of solar energy absorbed. However, CPV systems are still in a stage of development where new designs, methods and materials are still being created in order to reach a low levelled cost of energy comparable to standard silicon based PV systems. This article outlines the different types of concentration photovoltaic systems, their various design advantages and limitations, and noticeable trends. This will include comparisons on materials used, optical efficiency and optical tolerance (acceptance angle). As well as reviewing the recent development in the most commonly used and most established designs such as the Fresnel lens and parabolic trough/dish, novel optics and materials are also suggested. The aim of this review is to provide the reader with an understanding of the many types of solar concentrators and their reported advantages and disadvantages. This review should aid the development of solar concentrator optics by highlighting the successful trends and emphasising the importance of novel designs and materials in need of further research. There is a vast opportunity for solar concentrator designs to expand into other scientific fields and take advantage of these developed resources. Solar concentrator technologies have many layers and factors to be considered when designing. This review attempts to simplify and categorise these layers and stresses the significance of comparing as many of the applicable factors as possible when choosing the right design for an application. From this review, it has been ascertained that higher concentration levels are being achieved and will likely continue to increase as high performance high concentration designs are developed. Fresnel lenses have been identified as having a greater optical tolerance than reflective parabolic concentrators but more complex homogenisers are being developed for both system types which improve multiple performance factors. Trends towards higher performance solar concentrator designs include the use of micro-patterned structures and attention to detailed design such as tailoring secondary optics to primary optics and vice-versa. There is still a vast potential for what materials and surface structures could be utilised for solar concentrator designs especially if inspiration is taken from biological structures already proven to manipulate light in nature.

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Optics for concentrating photovoltaics: Trends, limits and opportunities for materials and design

Hydrogen from solar energy, a clean energy carrier from a sustainable source of energy

Performance enhancement of a Building-Integrated Concentrating Photovoltaic system using phase change material

Compound parabolic concentrator (CPC) has been gaining ever-increasing attention from academic researchers and industrial developers owing to its stationary feature for solar energy collection with a higher efficiency. As a low concentration concentrator with a larger acceptance angle and without a tracking requirement, it is an attractive solution to improve the system performance and reduce the cost of photovoltaic (PV) system, solar thermal system, daylighting and lighting systems, etc. This study will present a comprehensive and up-to-date review of its design principles for miscellaneous configurations, applications, performance predictions and technological advances. Numerous technically focused studies since 2000 will be introduced and summarized. Finally, the outlook focusing on CPC designs and improvements will be proposed.

/pdf/a-review-on-the-recent-research-progress-in-the-compound-qs7zwmq1i2.pdf

A review on the recent research progress in the compound parabolic concentrator (CPC) for solar energy applications

Potential of building integrated and attached/applied photovoltaic (BIPV/BAPV) for adaptive less energy-hungry building’s skin: A comprehensive review

Due to the dramatic advances in commercial multi-junction solar cells with 40% conversion efficiency, solar concentrator capable of delivering flux levels of hundreds to thousands of suns at high collective efficiency is the key factor for the success of novel Concentrator Photovoltaic (CPV) system. This paper would review and survey the progress in the last 30 years including the optical design and development in the optics of solar concentrators for the CPV system. The detailed architectural design and optical principle of solar concentrators are presented to show various innovative and creative ideas of harnessing solar energy.

Design and development in optics of concentrator photovoltaic system

A novel on-axis general sun-tracking formula has been integrated in the algorithm of an open-loop sun-tracking system in order to track the sun accurately and cost effectively. Sun-tracking errors due to installation defects of the 25 m2 prototype solar concentrator have been analyzed from recorded solar images with the use of a CCD camera. With the recorded data, misaligned angles from ideal azimuth-elevation axes have been determined and corrected by a straightforward changing of the parameters' values in the general formula of the tracking algorithm to improve the tracking accuracy to 2.99 mrad, which falls below the encoder resolution limit of 4.13 mrad.

Integration of an On-Axis General Sun-Tracking Formula in the Algorithm of an Open-Loop Sun-Tracking System

A method to study the solar flux distributions of the solar images reflected by mirrors with different dielectric thicknesses is proposed in this paper. An optical scanner, also known as a flux mapping system, capable of acquiring the flux distribution pattern of a light source in a two-dimensional flat surface, has been designed and constructed. The optical scanner can measure the profile of flux distribution at reasonably high resolution with fewer photo-sensors with a fast scanning speed of several seconds. The real time measurement results of solar images projected by mirrors with dielectric thicknesses, i.e., 3 mm, 4 mm, 5 mm and 6 mm, have been performed to analyze their surface qualities.

Study of image quality of mirror via solar flux distribution measurement using a high speed optical scanner

Solar concentrating device plays an important role by making use of optical technology in the design, which can be either reflector or lens to deliver high flux of sunlight onto the Concentrator Photovoltaic (CPV) module receiver ranging from hundreds to thousand suns. To be more competitive compared with fossil fuel, the current CPV systems using Fresnel lens and Parabolic dish as solar concentrator that are widely deployed in United States, Australia and Europe are facing great challenge to produce uniformly focused sunlight on the solar cells as to reduce the cost of electrical power generation. The concept of non-imaging optics is not new, but it has not fully explored by the researchers over the world especially in solving the problem of high concentration solar energy, which application is only limited to be a secondary focusing device or low concentration device using Compound Parabolic Concentrator. With the current advancement in the computer processing power, we has successfully invented the non-imaging dish concentrator (NIDC) using numerical simulation method to replace the current parabolic dish as primary focusing device with high solar concentration ratio (more than 400 suns) and large collective area (from 25 to 125 m2). In this paper, we disclose our research and development on dense array CPV system based on non-imaging optics. The geometry of the NIDC is determined using a special computational method. In addition, an array of secondary concentrators, namely crossed compound parabolic concentrators, is also proposed to further focus the concentrated sunlight by the NIDC onto active area of solar cells of the concentrator photovoltaic receiver. The invention maximizes the absorption of concentrated sunlight for the electric power generation system.

Sing-Liong Lau

Papers

Design and development in optics of concentrator photovoltaic system

Integration of an On-Axis General Sun-Tracking Formula in the Algorithm of an Open-Loop Sun-Tracking System

Study of image quality of mirror via solar flux distribution measurement using a high speed optical scanner

Dense-array concentrator photovoltaic system using non-imaging dish concentrator and crossed compound parabolic concentrator