Annual energy yield of mono- and bifacial silicon heterojunction solar modules with high-index dielectric nanodisk arrays as anti-reflective and light trapping structures

Abstract

While various nanophotonic structures applicable to relatively thin crystalline silicon-based solar cells were proposed to ensure effective light in-coupling and light trapping in the absorber, it is of great importance to evaluate their performance on the solar module level under realistic irradiation conditions. Here, we analyze the annual energy yield of relatively thin (crystalline silicon (c-Si) wafer thickness between 5 μm and 80 μm) heterojunction (HJT) solar module architectures when optimized anti-reflective and light trapping titanium dioxide (TiO2) nanodisk square arrays are applied on the front and rear cell interfaces, respectively. Our numerical study shows that upon reducing c-Si wafer thickness down to 5 μm, the relative increase of the annual energy yield can go up to 23.3 %rel and 43.0 %rel for mono- and bifacial solar modules, respectively, when compared to the reference modules with flat optimized anti-reflective coatings of HJT solar cells.

Antireflective Huygens’ Metasurface with Correlated Disorder Made from High-Index Disks Implemented into Silicon Heterojunction Solar Cells

“…However, the effect of encapsulation of the solar cell in a module tends to annihilate the advantage of the double ARC, while this is not the case for an optimized disk structure. 34 Additionally, the total current density for the periodic simulation in Table 2 and the corresponding discussion suggest that even higher current is possible to reach with the disk structure by further reducing the structure factor for small q.…”

“…We, therefore, refer to the recent work of Slivina et al for a detailed numerical analyses for similar but periodic light-trapping structures. 34 Otherwise, the most prominent deviation of about 4% abs is found around 650 nm and may be the result of slight differences between the model parameters of the FEM simulation and the real disks. For instance, the surface roughness on top of the disks (Figure 2, left) is not included in the simulation.…”

“…Another benchmark would be a double ARC stack, consisting of a MgF 2 layer on top of the ITO layer (each with optimized thickness), for which we estimate a current density increase of 1.5 mA/cm 2 (+4.7% rel ) compared to the standard flat ARC , (see SI, Figure S7 for reflectance and details). However, the effect of encapsulation of the solar cell in a module tends to annihilate the advantage of the double ARC, while this is not the case for an optimized disk structure . Additionally, the total current density for the periodic simulation in Table and the corresponding discussion suggest that even higher current is possible to reach with the disk structure by further reducing the structure factor for small q .…”

“…However, the structure was not optimized for light trapping and, given the relatively thick wafers, the experimental setup is not well suited for such an investigation. We, therefore, refer to the recent work of Slivina et al for a detailed numerical analyses for similar but periodic light-trapping structures . Otherwise, the most prominent deviation of about 4% abs is found around 650 nm and may be the result of slight differences between the model parameters of the FEM simulation and the real disks.…”

“…However, we note that through our fabrication process the disks can be applied to any surface, in principle irrespective of topography or material. Moreover, a structure composed of dielectric disks can potentially be integrated into the solar module, which was numerically shown in ref 34. The design of the disks is inspired by the concept of helicity preservation which, as we will show, also works in conjunction with a disk pattern of correlated disorder in the long wavelength limit.…”