Spectrum-splitting photovoltaics: Holographic spectrum splitting in eight-junction, ultra-high efficiency module

Escarra, Matthew D.; Darbe, Sunita; Warmann, Emily C.; Atwater, Harry A.

doi:10.1109/pvsc.2013.6744503

Cited by 17 publications

(10 citation statements)

References 6 publications

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“…This approach was used to develop specific implementations of spectrum splitting with practically achievable cells and optics. These designs are being developed as prototypes and are detailed in other publications .…”

Section: Resultsmentioning

confidence: 99%

Design of photovoltaics for modules with 50% efficiency

Warmann

Flowers

Lloyd

et al. 2017

Energy Science & Engineering

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A wide variety of photovoltaic cell technologies have shown dramatic performance improvements over the past decade, yet the prospect of a practical module capable of 50% efficiency remains remote. Experimentally achieved singlecell devices have achieved a record efficiency of 28.8% [1], which is close to the theoretical limit of 33.8% for such devices [2]. However, the single-cell limit is far below the fundamental efficiency limit for solar energy conversion of 74.0% for global illumination and 92.8% for direct [2] because a single pn junction can only efficiently convert photons with energy close to the value of its energy bandgap. The best single junction cell will lose more than 40% of the energy in the incident light to transmission of subbandgap photons and thermalization of carriers with photon energy in excess of the bandgap [3]. Spectrum splitting, which divides the solar spectrum into spectral bands of different energy and directs the bands onto multiple subcells with bandgap values matched to the energy of their photon allocation, is a necessary feature of any photovoltaic design capable of achieving >33.8% efficiency. The use of multiple subcells to increase conversion efficiency is well known. In these designs, the subcells are grown monolithically in a stacked configuration and are electrically in series. The incident spectrum is divided among the subcells by sequential absorption, with the top subcells absorbing and converting high energy photons

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Section: Resultsmentioning

confidence: 99%

Design of photovoltaics for modules with 50% efficiency

Warmann

Flowers

Lloyd

et al. 2017

Energy Science & Engineering

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“…Thus, we incorporate eight subcells as four dual junctions and use a compound parabolic concentrator (CPC) for external concentration. We introduced this design concept, which uses a higher number of subcells than any previous effort, in prior work, where we also showed that larger numbers of subcells are necessary to achieve very high‐efficiency photovoltaics. In this work, we present the detailed study of the potential for holographic spectrum splitting with stacked gratings and a larger number of subcells.…”

Section: Introductionmentioning

confidence: 99%

Simulation and partial prototyping of an eight‐junction holographic spectrum‐splitting photovoltaic module

Darbe

Escarra

Warmann

et al. 2019

Energy Science & Engineering

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Spectrum‐splitting photovoltaics incorporate optical elements to separate sunlight into frequency bands, which can be targeted at solar cells with bandgaps optimized for each sub‐band. Here, we present the design of a holographic diffraction grating‐based spectrum‐splitting photovoltaic module integrating eight III‐V compound semiconductor cells as four dual‐junction tandems. Four stacks of simple sinusoidal volume phase holographic diffraction gratings each simultaneously split and concentrate sunlight onto cells with bandgaps spanning the solar spectrum. The high‐efficiency cells get an additional performance boost from concentration incorporated using a single or a compound trough concentrator, providing up to 380X total concentration. Cell bandgap optimization incorporated an experimentally derived bandgap‐dependent external radiative efficiency function. Simulations show 33.2% module conversion efficiency is achievable. One grating stack is experimentally fabricated and characterized.

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“…By utilizing III-V triple junction solar cells in the tCPV module, with lowest bandgap around 1.4 eV, ultraviolet (UV) and visible light is directly absorbed and converted to electricity, while infrared (IR) light will pass through the cells and module to be captured by a solar thermal receiver and stored as heat. This spectrum splitting approach is angle insensitive and very high efficiency relative to other spectrum splitting approaches [6,31]. The tCPV module can be kept below 110°C, where cells optimally perform, while the cavity thermal receiver can heat the heat transfer fluid (HTF) to greater than 570°C.…”

Section: Introductionmentioning

confidence: 99%

A transmissive, spectrum-splitting concentrating photovoltaic module for hybrid photovoltaic-solar thermal energy conversion

Riggs

et al. 2016

Solar Energy

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A spectrum splitting, transmissive concentrating photovoltaic (tCPV) module is proposed and designed for a hybrid photovoltaic-solar thermal (PV/T) system. By utilizing III-V triple junction solar cells with bandgaps of 2.1eV/1.7eV/1.4eV, ultraviolet (UV) and visible light will be absorbed and converted to electricity, while infrared (IR) light will pass through and be captured by a solar thermal receiver and stored as heat. The stored thermal energy may be dispatched as electricity or process heat, as needed. According to the numerical analysis, the tCPV module can perform with overall power conversion efficiency exceeding 43.5% for above bandgap (in-band) light under a standard AM1.5D solar spectrum, under an average concentration ratio of 400 suns. Passive and active cooling methods, keeping cells below 110°C, are also investigated and discussed, indicating that a transparent active cooling design could improve the CPV module efficiency by around 1% (absolute), relative to a passive design, by reducing the maximum cell working temperature by around 16°C.

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Spectrum-splitting photovoltaics: Holographic spectrum splitting in eight-junction, ultra-high efficiency module

Cited by 17 publications

References 6 publications

Design of photovoltaics for modules with 50% efficiency

Design of photovoltaics for modules with 50% efficiency

Simulation and partial prototyping of an eight‐junction holographic spectrum‐splitting photovoltaic module

A transmissive, spectrum-splitting concentrating photovoltaic module for hybrid photovoltaic-solar thermal energy conversion

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