From component to multi-junction solar cells for spectral monitoring

Abstract

Concentrator photovoltaic usually embeds multi-junction solar cells, which exhibit high spectral sensitivity due to the internal series connection of the sub-cells. The use of so-called isotype or component cells with the same spectral response as the corresponding sub-cell, is widely applied for characterizing the spectral content of the impinging irradiance. These isotype sensors can be substituted by the multi-junction cells themselves, which are inherently spectrally tuned to any evolution of the multi-junction technology. To convert a multi-junction cell in a spectral sensor, it is necessary to add bias light within the spectral response of all but one of the sub-cells to saturate the corresponding junctions, so the nonsaturated limits the current under any specified impinging spectrum. This paper shows indoor and outdoor side-by-side comparison of the so-called pseudo isotypes, based on a triple-junction solar cell, and genuine isotypes. The conditions to ensure an accurate spectral response, particularly for the bottom pseudo-isotype, are presented and discussed.

Integrated Micro‐Scale Concentrating Photovoltaics: A Scalable Path Toward High‐Efficiency, Low‐Cost Solar Power

“…[ 56 ] In addition, aligning cell‐optic at a micron scale is difficult. [ 57,58 ] For this case, internal tracking enabled by the small size of the optics offers an intermediate solution as the implementation of an actuated solar cell or optical plane increases the complexity of the module. [ 42 ]…”

“…The polymer is heated beyond the glassification temperature and structured with the mold. This can be used for PMMA lenses or elastomer on glass (EoG), which need an additional degasification step; [ 125 ] 3) compression‐/injection‐/overmolding is used for solid plastic/silicone lenses, limited in size. Overmolding is a subcategory of injection molding, adding structured material to existing parts.…”

“…Misalignment between cells and optics poses an even greater challenge in micro‐CPV. [ 58,114 ] The submillimeter size leads to low mechanical tolerances (10–100 μm) so high precision manufacturing and assembly processes are mandatory, a challenge which conventional CPV faces and only exacerbates in micro‐CPV. Self‐alignment processes have been proposed making use of surface tension of melted solder, achieving cell positioning accuracy within ± 10 μm.…”

“…Examples of synergies with other industries for micro-CPV. Telecommunications industry: RFID [163] Hot-embossing of plastics Potential uses for micro-CPV optics Medical industry: lab-on-chip devices [125] Very precise packaging technologies COI (chip-on-interposer) and large-area assembly Photonics industry [44] Waveguides Light-guiding optics such as the examples given in Table 1 Photonics industry [37,116] To summarize the current prototypes, in Table 7, we present an extension of Table 1, in which we defined certain parameters to facilitate comparison between the technologies: 1) integrated tracking span (T Span ): the incidence angle at which the optical efficiency drops to 90% of maximum efficiency. This is equivalent to the optical acceptance angle in the presence of tracking, resulting in expanded acceptance angles compared to static systems.…”