We have characterized antireflection (AR) moth-eye films placed on top of crystalline silicon photovoltaic (PV) modules by indoor and outdoor experiments and examined improvements in conversion efficiency. The effects of the ratio of diffuse solar irradiation to total solar irradiation (diffusion index) and incident angle on efficiency have been quantitatively analyzed. Using computer simulations, yearly efficiency improvements under different installation conditions have been projected. We have shown that the use of AR moth-eye films offers the best advantages. Further, vertical tilt angle installation leads to the highest efficiency improvement, whereas spectral matching with the PV modules influences the efficiency improvement.

Near-to-far-field radiative heat transfer between two macroscopic SiO2 plates—with and without microcavities—was observed using a highly precise and accurate optical gap-measurement method. The experiments, conducted near 300 K, measured heat transfer as a function of gap separation from 1.0 μm to 50 μm and also as a function of temperature differences between 4.1 and 19.5 K. The gap-dependent heat flux was in excellent agreement with theoretical predictions. Furthermore, the effects of microcavities on the plate surfaces were clearly observed and significant enhancement of near-field radiative heat transfer was confirmed between gold-coated microcavities with narrow vacuum separation.

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