Dense-array Concentrator Photovoltaic System Research Articles

Multi-physics effects on the performance of Dense-array Concentrator Photovoltaic System

Abstract In this paper, the multi-physics effects on the performance of dense array concentrator photovoltaic (DA-CPV) system are investigated in detail by considering CPV module connections, non-uniform illumination, and temperature distribution. It is observed that the optimized module configuration can significantly reduce the overall cells temperature and then improve the efficiency and stability. We also analyze the effects of temperature uniformity on output performance. When the illumination, configuration and mean temperature are certain, the temperature distribution can affect the output performance of the DA-CPV system. In the case of non-uniform illumination, the maximum power of the module will be achieved with an inverse Gaussian temperature distribution, instead of uniform temperature. Through this comprehensive understanding the temperature effects of the DA-CPV module, a suitable cooling system can be designed to reduce power loss.

Sun-tracking Method for Correcting Self-weight Induced Optical Misalignment in Dense-array Concentrator Photovoltaic System

Abstract To overcome self-weight induced optical misalignment has always been a great challenge in optimizing electrical performance of dense-array concentrator photovoltaic (CPV) system. In this article, the correction of elevation angle in the sun-tracking algorithm of non-imaging dish concentrator is proposed for recovering the deviated solar flux distribution caused by the structural deflection induced optical misalignment. Numerical simulation via ray-tracing technique has been employed to analyze the concentrated flux distribution and the simulated result has shown that the proposed method is proficient to restore the deviated solar flux distribution back to the center of the receiver for any elevation angle in the dense-array CPV system.

Prototype of Dense-array Concentrator Photovoltaic System Using Non-imaging Dish Concentrators and Cross Compound Parabolic Concentrator

Abstract The paper presents a novel dense-array concentrator photovoltaic prototype system consisted of primary non-imaging dish concentrator and secondary concentrator (an array of crossed compound parabolic lenses). The secondary optics has a geometrical concentration ratio of 5.998 but the average measured concentration ratio is only 4.07 suns. The losses are mainly attributed to both the Fresnel reflection at the interfaces and absorption of the dielectric material. The preliminary measured power conversion efficiency of the system is 17% due to significant optical loss incurred by the secondary concentrator.

Rectifying structural deflection effect of large solar concentrator via correction of sun-tracking angle in the concentrator photovoltaic system

The influence of self-weight structural deflection of large solar concentrator has caused significant impact to the quality of concentrated solar flux. The resulted negative outcomes from structural deflection, including image distortion and pointing error, can deteriorate the electrical power generated by dense-array concentrator photovoltaic (CPV) module located at the target of large solar concentrator. In this article, a novel corrective measure for sun-tracking angle is proposed to rectify the structural deflection effect on the large solar concentrator and hence to optimize the electrical output power of dense-array CPV module. The methodology of the proposed corrective measure has been formulated and discussed in details using numerical simulation via ray-tracing technique. The simulated result has shown that the proposed method is proficient to recover the deviated and distorted solar flux distribution in the receiver without affecting the maximum solar concentration ratio and hence to reduce the electrical power loss. For the overall gain, the maximum output power has been increased from 3562W to 4030W and the electrical power loss has been reduced from 12.4% to 0.8% at elevation angle of 60° in the dense-array CPV system.

Influence of self-weight on electrical power conversion of dense-array concentrator photovoltaic system

New methodology of analyzing the influence of self-weight structural deflection towards the power conversion loss of dense-array concentrator photovoltaic (CPV) system has been formulated. As a case study, a three-dimensional mechanical model has been created based on the 23-m2 non-imaging dish concentrator (NIDC) prototype in which self-weight mechanical deflection and the consequent effect to the optical performance have been carried out at various elevation angles to determine the solar flux distributions. Finally, the overall power conversion of dense-array solar cells by taking into account of solar flux distribution has been simulated. For elevation angle of 60°, the energy variation and solar concentration ratio variation of solar flux distribution are 3.2% and 43% respectively as compared to ideal circumstance without self-weight deflection. The resulted maximum power conversion loss is 12.4%. The influence of self-weight on NIDC has significant impact to both the image distortion and pointing error of the solar flux distribution, which is one of major reasons to deteriorate the electrical power conversion of the CPV system.

Performance study of crossed compound parabolic concentrator as secondary optics in non-imaging dish concentrator for the application of dense-array concentrator photovoltaic system

Optical and electrical analyses of non-imaging dish concentrator (NIDC) with secondary concentrator for the application in dense-array concentrator photovoltaic (CPV) system are presented. Array of crossed compound parabolic concentrator (CCPC) lenses is selected as secondary concentrator due to high acceptance angle, larger entrance aperture to provide more space for high flexibility of inter-connection among CPV cells, and square exit aperture matching well with commercial CPV cell. Electrical performance of integrated CPV cells with CCPC lenses (CPV+CCPC) assembly module is analyzed for different pointing errors: 0°, 0.1°, 0.2°, 0.3° & 0.4°, and the results are compared to that of dense-array CPV (DACPV) module. It was found that overall electrical performance of CPV+CCPC assembly module is better than that of DACPV module despite using 77% less CPV cells than that of DACPV module.

Performance optimization of dense-array concentrator photovoltaic system considering effects of circumsolar radiation and slope error.

This paper presents an approach to optimize the electrical performance of dense-array concentrator photovoltaic system comprised of non-imaging dish concentrator by considering the circumsolar radiation and slope error effects. Based on the simulated flux distribution, a systematic methodology to optimize the layout configuration of solar cells interconnection circuit in dense array concentrator photovoltaic module has been proposed by minimizing the current mismatch caused by non-uniformity of concentrated sunlight. An optimized layout of interconnection solar cells circuit with minimum electrical power loss of 6.5% can be achieved by minimizing the effects of both circumsolar radiation and slope error.

Optical characterization of nonimaging dish concentrator for the application of dense-array concentrator photovoltaic system

Optimization of the design of a nonimaging dish concentrator (NIDC) for a dense-array concentrator photovoltaic system is presented. A new algorithm has been developed to determine configuration of facet mirrors in a NIDC. Analytical formulas were derived to analyze the optical performance of a NIDC and then compared with a simulated result obtained from a numerical method. Comprehensive analysis of optical performance via analytical method has been carried out based on facet dimension and focal distance of the concentrator with a total reflective area of 120 m2. The result shows that a facet dimension of 49.8 cm, focal distance of 8 m, and solar concentration ratio of 411.8 suns is the most optimized design for the lowest cost-per-output power, which is US$1.93 per watt.

Study of automotive radiator cooling system for dense-array concentration photovoltaic system

An automotive radiator is proposed for the heat rejection of the dense-array concentrator photovoltaic (CPV) system. Theoretical modeling on the integration of automotive radiator into the cooling system with a specially designed cooling block has been carried out in details. To verify the feasibility of new proposal, the automotive radiator cooling system has been constructed and tested to effectively lower down the temperature of CPV module in a non-imaging planar concentrator prototype with total reflective area of 4.16m2 at solar concentration ratio of 377suns. During the on-site measurement, it has been observed that the conversion efficiency of CPV module has successfully improved from 22.39% to 26.85% when the CPV cell temperature is reduced from 59.4°C to 37.1°C.