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Hybrid concentrator photovoltaic (CPV) architectures that combine CPV modules with low-cost solar cells have the advantage of functioning well in modest direct normal irradiance (DNI) regions as well as high-DNI regions, where these architectures allow for higher performance in a limited space. For higher performance of a hybrid CPV module, we optimized the secondary optical element (SOE) using raytracing software and conducted experimental measurements that consider the effective wavelength range. Our experiments with the optimized SOE (θ = 30°, h = 15 mm) demonstrated a maximum output power on the triple-junction cell and polycrystalline silicon cell of 212.8 W/m2 and 5.14 W/m2, respectively. [ABSTRACT FROM AUTHOR]

Hybrid concentrator photovoltaic (CPV) architectures that combine CPV modules with low-cost solar cells have the advantage of functioning well in modest direct normal irradiance (DNI) regions as well as high-DNI regions, where these architectures allow for higher performance in a limited space. For higher performance of a hybrid CPV module, we optimized the secondary optical element (SOE) using raytracing software and conducted experimental measurements that consider the effective wavelength range. Our experiments with the optimized SOE (θ = 30°, h = 15 mm) demonstrated a maximum output power on the triple-junction cell and polycrystalline silicon cell of 212.8 W/m2 and 5.14 W/m2, respectively.

The goal of this presented study was to determine the optimum parameters of secondary optical elements (SOEs) for concentrated photovoltaic (CPV) units with flat Fresnel lenses. Three types of SOEs are under consideration in the design process, including kaleidoscope with equal optical path design (KOD), kaleidoscope with flat top surface (KFTS), and open-truncated tetrahedral pyramid with specular walls (SP). The function of using a SOE with a Fresnel lens in a CPV unit is to achieve high optical efficiency, low sensitivity to the sun tracking error, and improved uniformity of irradiance distribution on the solar cell. Ray tracing technique was developed to simulate the optical characteristics of the CPV unit with various design parameters of each type of SOE. Finally, an optimum KOD-type SOE was determined by parametric design process. The resulting optical performance of the CPV unit with the optimum SOE was evaluated in both single-wavelength and broadband simulation of solar spectrum.

Lattice-matched monolithic triple-junction Concentrator Photovoltaic cells (InGa (0.495) P/GaIn (0.012) As/Ge) were electrically and thermally interfaced to two Thermoelectric Peltier module designs. An electrical and thermal model of the hybrid receivers was modelled in COMSOL Multiphysics software v5.3 to optimize cell cooling whilst increasing photon energy conversion efficiency. The receivers were measured for current–voltage characteristics with the cell only (with sylguard encapsulant), under single secondary optical element at x2.5 optical concentration, and under Fresnel lens primary optical element concentration between x313 and x480. Measurements were taken in solar simulators at Cardiff and Jaén Universities, and on-sun with dual-axis tracking at Jaén University. The hybrid receivers were electrically, thermally and theoretically investigated. The electrical performance data for the cells under variable irradiance and cell temperature conditions were measured using the integrated thermoelectric module as both a temperature sensor and as a solid-state heat pump. The performance of six hybrid devices were evaluated within two 3-receiver strings under primary optical concentration with measured acceptance angles of 1.00° and 0.89°, similar to commercially sourced Concentrator Photovoltaic modules. A six-parameter one-diode equivalent electrical model was developed for the multi-junction cells under both primary and secondary optical concentration. This was applied to extract six model parameters with the experimental current–voltage curves of type A receiver at 1, 3 and 500 concentration ratios. Standard test conditions (1000 W/m 2 , 25 °C and Air Mass 1.5 Global spectrum) were assumed based on trust-region-reflective least squares algorithm in MATLAB. The model fitted the experimental current–voltage curves satisfactorily with a mean error of 4.44%. The combined primary and secondary optical intensity gain coefficient is as high as 0.92, in comparison with 0.50–0.86 for crossed compound parabolic concentrators. The determined values of diode reverse saturation current, combined series resistance and shunt resistance were similar to those of monocrystalline PV cell/modules in our previous publications. The model may be applicable to performance prediction of multi-junction CPV cells in the future. [ABSTRACT FROM AUTHOR]

The closed‐loop integrated cooler (CLIC) is a novel technique deployed on experimental apparatus to accurately measure, monitor and control the temperature of optoelectronic devices. Demonstrated here within a concentrator photovoltaic–thermoelectric (CPV–TE) hybrid device, the thermoelectric module was used as a solid‐state sensor and heat pump in order to control the operational temperature for a triple‐junction solar cell. The technique was used to achieve stable, reproducible and repeatable standard test conditions of 25°C cell temperature, with 1000 W/m2 irradiance and AM1.5G spectrum. During testing with secondary optical element (SOE) optics in a solar simulator, the CLIC enabled accurate temperature control of the CPV cell. This would otherwise be unfeasible due to the spectral, reflective and diffusive effects of the SOE optics. The CLIC was used to obtain temporal and spatial constant temperature of the CPV‐TE hybrid receiver during current–voltage measurement. This method highlights the future potential of the CLIC for accurate temperature control of optoelectronic devices both during testing and in future semiconductor device applications where temperature control is essential to performance or lifetime. [ABSTRACT FROM AUTHOR]

Multi-junction solar cells can be economically viable for terrestrial applications when operated under concentrated illuminations. The optimal design of concentrator optics in high concentration photovoltaics (HCPV) systems is crucial for achieving high energy conversion. At a high geometric concentration, chromatic aberration of the primary lens can restrict the optical efficiency and acceptance angle. In order to correct chromatic aberration, multi-material, multi-element refractive elements, hybrid refractive/diffractive elements, or multi-element refractive and diffractive systems can be designed. In this paper, the effect of introducing a diffractive surface in the optical path is analyzed. An example two-stage refractive and diffractive optical system is shown to have an optical efficiency of up to 0.87, and an acceptance angle of up to ±0.55° with a 1600× geometric concentration ratio, which is a significant improvement compared to a single-stage concentrator system with a single material. This optical design can be mass-produced with conventional fabrication methods, thus providing a low-cost alternative to other approaches, and the design approach can be generalized to many other solar concentrator systems with different cell sizes and geometric concentration ratios.

A lattice-matched monolithic triple-junction Concentrator Photovoltaic cell (InGa (0.495) P/GaIn (0.012) As/Ge) was electrically and thermally interfaced to a Thermoelectric Peltier module. A single optical design secondary lens was bonded to the CPV-TE receiver. The hybrid SILO-CPV-TE solar energy harvesting device was electrically, thermally and theoretically investigated. The electrical performance data for the cell under variable irradiance and cell temperature conditions were measured using the integrated thermoelectric module as both a temperature sensor and as a solid-state heat pump. The cell was electrically characterised under standard test conditions (1000 W/m 2 irradiance, 25°C temperature and AM1.5G spectrum) for comparison with literature data. Transient multiphysics simulations in ANSYS CFX 15.0 were carried out to calculate cell temperatures and to determine the short circuit current and temperature coefficient in a scaling law. The optimization was used to determine 15 model parameters for the component sub-cells within the triple-junction cell at STC with a MATLAB scaling law. The root-mean-square error in electrical currents between measurement and simulations was 0.66%. [ABSTRACT FROM AUTHOR]

• Novel CPV/T system with liquid spherical lens as secondary optical element. • Secondary optical element and spectral beam splitting filter are merged into one. • Irradiation unavailable to solar cell is used for heating electrolyte. • A solar-to-hydrogen efficiency of 22.7% is achievable in experiments. How to efficiently convert solar radiation into energy sources for easy storage and consumption is an urgent issue. Although concentrated photovoltaics can achieve high efficiency, it places higher demands on the optical system and heat management. Herein, a new design is presented where a liquid spherical lens acts as a secondary optical element of the concentrating solar system, refracting the light beam while participating in spectral beam splitting. The radiation energy unavailable for solar cells is harvested by the liquid spherical lens through spectral beam splitting which serves to raise the temperature of the electrolyte. Compared with the conventional concentrated photovoltaic coupled electrolytic hydrogen production system, the addition of a liquid spherical lens improves the solar cell heat dissipation while increasing the operating temperature of the electrolyzer, achieving higher solar-to-hydrogen efficiency. The system with this design obtains a solar-to-electricity efficiency of 31.7% as verified by indoor experiments. The solar-to-hydrogen efficiency of the system achieved an average value of 22.1% and a benchmark maximum value of 22.7% during 7 h of continuous operation. The solar-to-hydrogen efficiency is improved by at least 10% compared to the design that separates the secondary optics from the spectral beam-splitting filter. Compared with existing systems employing commercial CPV modules, the efficiency is improved by at least 6% benefiting from the rational distribution of the spectrum by the liquid spherical lens. [ABSTRACT FROM AUTHOR]

Multi-junction solar cells can be economically viable for terrestrial applications when operated under concentrated illuminations. The optimal design of concentrator optics in high concentration photovoltaics (HCPV) systems is crucial for achieving high energy conversion. At a high geometric concentration, chromatic aberration of the primary lens can restrict the optical efficiency and acceptance angle. In order to correct chromatic aberration, multi-material, multi-element refractive elements, hybrid refractive/diffractive elements, or multi-element refractive and diffractive systems can be designed. In this paper, the effect of introducing a diffractive surface in the optical path is analyzed. An example two-stage refractive and diffractive optical system is shown to have an optical efficiency of up to 0.87, and an acceptance angle of up to ±0.55° with a 1600× geometric concentration ratio, which is a significant improvement compared to a single-stage concentrator system with a single material. This optical design can be mass-produced with conventional fabrication methods, thus providing a low-cost alternative to other approaches, and the design approach can be generalized to many other solar concentrator systems with different cell sizes and geometric concentration ratios. [ABSTRACT FROM AUTHOR]