• Energy Research

Energy yield (EY) modelling is an indispensable tool to minimize payback time of emerging perovskite-based multi-junction photovoltaics (PV) but it relies on many assumptions about device architecture and environmental conditions. Here, we propose a comprehensive framework that enables rapid simulation of complex architectures of perovskite-based multi-junction PV and detailed calculation of their power output under realistic irradiation conditions in various climatic zones. Applying the framework to perovskite/silicon multi-junction solar modules, we showcase the impact of tracking on energy losses arising from spectral variations. Moreover, we demonstrate the strong dependency of the EY of bifacial multi-junction solar modules on the albedo.

Energy yield (EY) modelling is an indispensable tool to minimize payback time of emerging perovskite-based multi-junction photovoltaics (PV) but it relies on many assumptions about device architecture and environmental conditions. Here, we propose a comprehensive framework that enables rapid simulation of complex architectures of perovskite-based multi-junction PV and detailed calculation of their power output under realistic irradiation conditions in various climatic zones. Applying the framework to perovskite/silicon multi-junction solar modules, we showcase the impact of tracking on energy losses arising from spectral variations. Moreover, we demonstrate the strong dependency of the EY of bifacial multi-junction solar modules on the albedo.

Recent advances in solution processing of micrometer-thick perovskite solar cells over textured silicon bottom solar cells allowed a new promising approach for the fabrication of 2T perovskite/silicon tandem photovoltaics, combining optimal light management in the textured bottom cell with the ease of solution processing. Detailed simulations are needed to assess the performances of this morphology configuration (thick perovskite configuration). In this work, in-depth optical and energy yield (EY) simulations are performed to compare the thick perovskite configuration with other relevant morphology configurations for 2T perovskite/silicon tandem photovoltaics. Under standard test conditions, the total photogenerated current of the thick perovskite configuration is 1.3 mA cm−2 lower (−3.4% relative) than the one of the conformal perovskite on textured silicon configuration for non-encapsulated cells and only 0.8 mA cm−2 (−2.1% relative) for encapsulated cells. Under realistic outdoor conditions, EY modelling for a wide range of locations shows that, while conformal perovskite on textured silicon configuration remains the optimal configuration, thick perovskite configuration exhibits a mere ∼2.5% lower annual EY. Finally, intermediate scenarios are investigated with the angle of the perovskite front-side texture differing from the silicon texture and critical angles for efficient light management in these configurations are identified.

Recent advances in solution processing of micrometer-thick perovskite solar cells over textured silicon bottom solar cells allowed a new promising approach for the fabrication of 2T perovskite/silicon tandem photovoltaics, combining optimal light management in the textured bottom cell with the ease of solution processing. Detailed simulations are needed to assess the performances of this morphology configuration (thick perovskite configuration). In this work, in-depth optical and energy yield (EY) simulations are performed to compare the thick perovskite configuration with other relevant morphology configurations for 2T perovskite/silicon tandem photovoltaics. Under standard test conditions, the total photogenerated current of the thick perovskite configuration is 1.3 mA cm−2 lower (−3.4% relative) than the one of the conformal perovskite on textured silicon configuration for non-encapsulated cells and only 0.8 mA cm−2 (−2.1% relative) for encapsulated cells. Under realistic outdoor conditions, EY modelling for a wide range of locations shows that, while conformal perovskite on textured silicon configuration remains the optimal configuration, thick perovskite configuration exhibits a mere ∼2.5% lower annual EY. Finally, intermediate scenarios are investigated with the angle of the perovskite front-side texture differing from the silicon texture and critical angles for efficient light management in these configurations are identified.

Nature’s evolution provides a multitude of answers to scientific and key technological challenges such as the light harvesting. In this work, we investigate the optical properties of the unique texture of viola petals for the purpose of improved light harvesting in photovoltaics. We find that crystalline silicon solar cells encapsulated with a transparent coating show a 6% improvement in power conversion efficiency if the viola petal texture is replicated onto the front surface. This gain is based on a broadband enhancement in current generation that originates from the exceptional optical properties of the viola surface texture, combining micro- and nanotexture. The microcones of this hierarchical texture demonstrate strong and broadband light incoupling effects as well as retro-reflection capabilities, and the nanowrinkles further decrease the reflection losses. Using rigorous optical simulation, we analyze and explain the working principle ruling the light harvesting properties of this dual-scale texture.

Nature’s evolution provides a multitude of answers to scientific and key technological challenges such as the light harvesting. In this work, we investigate the optical properties of the unique texture of viola petals for the purpose of improved light harvesting in photovoltaics. We find that crystalline silicon solar cells encapsulated with a transparent coating show a 6% improvement in power conversion efficiency if the viola petal texture is replicated onto the front surface. This gain is based on a broadband enhancement in current generation that originates from the exceptional optical properties of the viola surface texture, combining micro- and nanotexture. The microcones of this hierarchical texture demonstrate strong and broadband light incoupling effects as well as retro-reflection capabilities, and the nanowrinkles further decrease the reflection losses. Using rigorous optical simulation, we analyze and explain the working principle ruling the light harvesting properties of this dual-scale texture.

AbstractMicron‐scale textures at the front surface of solar modules have been reported to improve the current generation by both enhancing light in‐coupling as well as by reducing light out‐coupling via back‐reflection, similar to the retroreflective effect. Whereas the general working principle and advantages of these textures have been described previously, here, the interplay of the reflection properties of different substrates with the enhancement effects is analyzed for textures of conical geometry. The study takes into consideration the incident light of arbitrary angle of incidence as well as the overall energy yield. Supported by optical simulations, periodic micro‐cone textures were optimized and prototyped based on direct laser writing and a scalable replication process. Micron‐scale textures with cones of various aspect ratios were examined on mono‐crystalline silicon (c‐Si) solar cells; an optimum aspect ratio of 0.73 was identified. This moderate aspect ratio is suitable for large‐scale replication, while showing near‐zero surface reflection and excellent light trapping. An increase in energy yield of up to 8% was calculated for the case of micro‐cone textures at the front surface of commercial alkaline‐etched c‐Si solar cells. Moreover, the excellent optical properties of the micro‐cone textures were highlighted by improving the power conversion efficiency (PCE) of a Cu(In,Ga)Se2 (CIGS) thin‐film solar cells from 20.2% to 20.9%. A comparable PCE improvement has been achieved by conventional MgF2 antireflection coatings, but the angular stability and in turn the energy yield of the micro‐cone textures is much higher.

AbstractMicron‐scale textures at the front surface of solar modules have been reported to improve the current generation by both enhancing light in‐coupling as well as by reducing light out‐coupling via back‐reflection, similar to the retroreflective effect. Whereas the general working principle and advantages of these textures have been described previously, here, the interplay of the reflection properties of different substrates with the enhancement effects is analyzed for textures of conical geometry. The study takes into consideration the incident light of arbitrary angle of incidence as well as the overall energy yield. Supported by optical simulations, periodic micro‐cone textures were optimized and prototyped based on direct laser writing and a scalable replication process. Micron‐scale textures with cones of various aspect ratios were examined on mono‐crystalline silicon (c‐Si) solar cells; an optimum aspect ratio of 0.73 was identified. This moderate aspect ratio is suitable for large‐scale replication, while showing near‐zero surface reflection and excellent light trapping. An increase in energy yield of up to 8% was calculated for the case of micro‐cone textures at the front surface of commercial alkaline‐etched c‐Si solar cells. Moreover, the excellent optical properties of the micro‐cone textures were highlighted by improving the power conversion efficiency (PCE) of a Cu(In,Ga)Se2 (CIGS) thin‐film solar cells from 20.2% to 20.9%. A comparable PCE improvement has been achieved by conventional MgF2 antireflection coatings, but the angular stability and in turn the energy yield of the micro‐cone textures is much higher.