RESUMEN
Ultra-high concentrator photovoltaic systems aim to enhance the conversion efficiency of sunlight and to reduce the cost of electricity. However, it is still necessary to develop optical systems with higher efficiencies and angular tolerances for them to become a reality. This Letter proposes a novel design that is able to achieve a geometric concentration of 4096×. The system consists of four concentrator units based on parabolic mirrors and optical guides that concentrate the sunlight onto a single cell. Additionally, a preliminary proof-of-concept module has been assembled for validation purposes. The novel design exceeds the optical efficiency of the existing systems, ≈84%, and offers almost double acceptance angles, ≈0.6∘.
RESUMEN
Soiling is the process whereby dirt, dust, and organic/inorganic contaminants deposit on the surface of a photovoltaic (PV) module. It causes significant economic losses and can have a substantial impact on the expansion of photovoltaic technologies for energy generation. The first step to address soiling adequately is monitoring, as soiling mitigation has to be tailored to the specific conditions of each PV system and no universally valid strategy exists. The main focus of this study is to assess the current state of the art in soiling monitoring, in order to help the community better understand the needs and the challenges in this area. The potentials and the limitations of each monitoring method are discussed thoroughly in the paper, with the support of original experimental data. An estimation of the future soiling monitoring market trends is also presented, with a forecasted need for tens of thousands of new soiling monitors every year.
RESUMEN
Ultra-High Concentrator Photovoltaic (UHCPV) designs with up to more than 6000× geometrical concentration and optical efficiency of 80% are demonstrated in this paper by means of ray tracing simulations. These are developed based on Cassegrain-Koehler concentrators [Opt. Lett.41(9), 1985 (2016)], with four pairs of paraboloid-hyperboloid mirrors and a central receiver composed of four Cartesian ovals of revolution. Designs at different geometrical concentrations are analyzed based on their aspect ratios (F-number). The most compact designs exhibit highest optical efficiencies. Moreover, a 3015× geometrical concentration one-cell prototype, made of aluminum and PMMA (poly(methyl methacrylate)), is fabricated and characterized indoors, achieving an effective concentration of 938 suns. This represents the CPV module with the highest geometrical concentration that has been experimentally investigated that could be found in the scientific literature.
RESUMEN
The accumulation of soiling on photovoltaic (PV) modules affects PV systems worldwide. Soiling consists of mineral dust, soot particles, aerosols, pollen, fungi and/or other contaminants that deposit on the surface of PV modules. Soiling absorbs, scatters, and reflects a fraction of the incoming sunlight, reducing the intensity that reaches the active part of the solar cell. Here, we report on the comparison of naturally accumulated soiling on coupons of PV glass soiled at seven locations worldwide. The spectral hemispherical transmittance was measured. It was found that natural soiling disproportionately impacts the blue and ultraviolet (UV) portions of the spectrum compared to the visible and infrared (IR). Also, the general shape of the transmittance spectra was similar at all the studied sites and could adequately be described by a modified form of the Ångström turbidity equation. In addition, the distribution of particles sizes was found to follow the IEST-STD-CC 1246E cleanliness standard. The fractional coverage of the glass surface by particles could be determined directly or indirectly and, as expected, has a linear correlation with the transmittance. It thus becomes feasible to estimate the optical consequences of the soiling of PV modules from the particle size distribution and the cleanliness value.
RESUMEN
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.
