Juan P. Ferrer-Rodríguez

Optical design of a 4-off-axis-unit Cassegrain ultra-high concentrator photovoltaics module with a central receiver.

Ultra-high concentrator photovoltaics (UHCPV), with concentrations higher than 1000 suns, have been pointed out by different authors as having great potential for being a cost-effective PV technology. This Letter presents a UHCPV Cassegrain-based optical design in which the sunrays are concentrated and sent from four different and independent paraboloid-hyperboloid pairs optical units onto a single central receiver. The optical design proposed has the main advantage of the achievement of ultra-high concentration ratios using relative small mirrors with similar performance values of efficiency, acceptance angle, and irradiance uniformity to other designs.

Energy yield assessment of a high concentration photovoltaic receiver based on simulated spectra from typical meteorological year datasets

The performance of High Concentration Photovoltaic (HCPV) receivers is influenced by changes in the solar spectrum and operating solar cell temperature (Tcell). Since the solar spectrum is affected by the variation of air mass (AM), aerosol optical depth (AOD) and precipitable water (PW), it is important to investigate their impact on the performance of HCPV receivers. It is also known that the direct normal irradiance (DNI) and ambient temperature (Tamb) are dominant factors that can influence the operating Tcell. In this study, Class I data from the NREL’s typical meteorological year (TMY3) database are used in order to predict the energy yield (Eyield) of a HCPV receiver in two USA sites with relatively high annual direct normal irradiation; Las Vegas, NV and Tucson, AZ. The results show that, although the annual average Tcell in Tucson is higher by 1.8°C and the number of “sunny hours” are 20 less than Las Vegas, the Eyield is still higher by 1.6%. The annual spectral losses in Las Vegas and Tucson we...

Indoor characterization and comparison with optical modelling of four Fresnel-based High-CPV units equipped with secondary optics

Numerous works analyze the refractive secondary optical elements (SOEs) in their application to HCPV modules, since the improvement in their optical tolerances, specifically, in the acceptance angle. Comparative theoretical and some experimental works are already published about this matter. However, this work also provide the validation of an optical modelling previously published, in which key features of the HCPV units were taken into account. Specially, that modelling considered wavelength-dependent properties in the light-matter interaction, like in the optical polychromatic efficiency of the solar cell (through its spectral response), or in the light absorption coefficient of the PMMA material. Then, four SOEs are manufactured and utilized to assemble different HCPV units to be characterized under controlled conditions in a CPV Solar Simulator. The four SOEs are: (i) SILO-Pyramid (SIngle-Lens-Opical elment), (ii) DCCPC (dielectric-cross compound-parabolic-concentrator), (iii) RTP (refractive truncated pyramid) and (iv) Trumpet. The correspondent HCPV units are characterized at 1000 W/m2 and at spectral conditions SMR = 1 under normal alignment respect to the simulated light and also at different tilted orientations. This last allows to measure the acceptance angle of each HCPV unit. These values are compared to those simulated by ray tracing. The results show measured acceptance angle values are in general similar to the simulated ones, with a deviation lower than 8%, except for the case of the SILO-Pyramid unit.

Design and characterization of refractive secondary optical elements for a point-focus Fresnel lens-based high CPV system

Point-focus Fresnel lens-based High Concentrator Photovoltaic (HCPV) systems are usually equipped with refractive secondary optical elements (SOE) in order to improve their performance. Two basic SOE designs are optically modeled and simulated in this work: Domed-Kaleidoscope (D-K) with breaking-symmetry top and SILO (SIngle-Lens-Optical element). Wavelength-dependent optical material properties like refractive index and absorption coefficient, as well as the spectral response of a typical triple-junction (TJ) solar cell, are included in the ray tracing simulations. Moreover, using a CPV Solar Simulator “Helios 3198”, both HCPV units are experimentally characterized. The acceptance angle characteristics of both HCPV units, obtained through optical simulations and through indoor characterization, are compared. The acceptance angle characteristic is better for the HCPV unit with the D-K SOE both in simulations and in experimental measurements, showing concordance between simulation and experiment. However, ...

Investigating the optical performance of Cassegrainian systems at ultra-high concentrations

A Cassegrainian optical design reaching ultra-high concentration fluxes (more than 1000 suns) is presented. The system is based on the use of four independent off-axis pairs of parabolic-hyperbolic reflectors that concentrate sunrays onto a central receiver (TOE, tertiary optical element) which works as a Kohler integrator. This design reaches an effective concentration ratio simulated of 1682 suns while using relative small mirrors. The acceptance angle characteristic is analyzed in terms of both the detailed ray tracing on the TOE and the irradiance pattern on the solar cell for a misalignment situation near to the acceptance angle of the design, which is 0.61°.

Global Annual Final AC Yield Comparison between HCPV and c-Si PV

A worldwide comparison of the annual yield between conventional c-Si photovoltaic (PV) technology and high concentrated photovoltaic (HCPV) technology is presented. The idea of this paper is to find the most appropriate locations for HCPV systems in terms of the annual energy produced when comparing to fixed tilt PV systems and two-axis oriented PY systems. For estimating the annual energy generation, the method of the Performance Ratio is used. For some locations with high annual direct normal irradiation values, which are distributed around the world, HCPV systems are found to be more advantageous than fixed tilt PV systems. World maps showing this comparison are presented.

Thin photovoltaic modules at ultra high concentration

A new design concept of high concentration photovoltaic (HCPV) module is studied both by ray-tracing simulation and by building a prototype. This set-up is based on the idea of concentrating sunlight from different optical units to a single commercial multi-junction solar cell, which is located in a different plane than that of the primary optics (e.g. Fresnel lenses). A two-optical-unit set-up, as a first approach, is built and measured with the solar simulator “Helios 3198”. These results are compared to the measurement results of the single-unit of one Fresnel lens and the same solar cell. The feasibility of this new design has been confirmed theoretically and practically.