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Two emerging trends in multicrystalline silicon cell texturing are plasma texturing, and metal catalyzed chemical etching. Both processes roughen silicon surfaces in order to increase light absorption. These processes are attractive as they are applicable to diamond-wire sawn wafers. This work investigates the optical properties of these surfaces, and other conventionally textured surfaces like isotropic acidic and random pyramid textures, are investigated for cells in air and after encapsulation for a large range of angles of incidence. We find that the angular optical performance in air varies strongly with cell texture, but when embedded in a module structure these variations are significantly mitigated: the advantages of a high angular absorption of solar cells are not fully transferred to the module level. This is especially notable for plasma etched, black silicon cell structures which suffer comparatively from poorer index matching and light recycling inside a module structure. The losses caused explicitly by the module embedding (described in the cell to module ratio) are in the range of 1–5% for perpendicular incoming light, and increase to 6–15% at an angle of incidence of 70°. Based on these angular performances, we calculate the annual yield of the modules and find that it varies by less than 2% for the cell textures. Nevertheless, the annual optical yield for the black silicon cell structures are the highest, whereas the metal catalyzed chemical etching cell structures show the lowest performance. Further, we find that different annual distributions of the incoming light at the two investigated locations (Melbourne and Alice Springs) only impact the relative performance of the cell textures at high module tilt angles.

High accuracy of yield prediction is of utmost importance for commercial scale photovoltaic systems. One key parameter crucial to the prediction accuracy is the choice and availability of reliable solar radiation data. In this work we investigate the impact of two fundamentally different irradiance data sources on the calculation of the yearly yield and performance ratio for five locations in different climatic regions of Australia. We find an overestimation of the yield calculation of up to 9.3% for satellite-based climate irradiance data compared against one-minute ground-based irradiance data. The yield overestimation shows a general correlation with the number of cloudy days. We propose a linear correction of the yield calculation which allows to improve the prediction accuracy based on more broadly available satellite-based irradiance data.

Solar cells and modules are usually optimized separately under standard test conditions (STC). However, the actual performance under field exposure depends on module design, installation and environmental conditions. This work therefore presents a methodology to predict the annual yield of crystalline silicon solar modules for varying module configurations and environments using a time step simulation approach. We define and quantify 12 effects that affect the annual module performance, starting with solar cells in air under STC to a complete module under realistic conditions. We consider the interaction of optical, thermal and electrical effects in the module and combine it with an angular, spectral and time resolved light source. The model enables understanding the impact of the module environment, such as regions with high wind speeds or high diffuse light, on the annual output of a particular module type. We validate our model with measured power and temperature data for crystalline silicon heterojunction solar cell modules and find an agreement of the annual yield within 0.7%. We quantify the annual gains and losses for this module and identify that major losses are caused by elevated operating temperatures (2.3%) and reflection losses at the front glass (2.6%). Critically, the coupling gains at the cell surface increase significantly by 1.5% when considering angular light irradiance compared to normal incidence. Finally, we apply our Cell-to-Module-Yield method to a 72-cell mono-crystalline PERC module, where the main annual yield losses are caused by reflection at the front glass and ohmic losses in the connector ribbons.

Minimizing the optical and electrical losses from cell to module is essential for highly efficient PV modules. We use metal wrap through (MWT) solar cells with passivated rear surface to integrate them into a PV-module and minimize the cell to module losses. For this purpose, we analyze the optical properties of different encapsulation materials with respect to this specific cell type, i.e. the absorption losses in the encapsulants and coupling gains from refractive index. The best performing encapsulant shows a cell-to-module power loss of 0% for a 16-cell MWT module. The fill factor loss is 1.4% absolute. We reach a module efficiency of 17.4% on the aperture area implying a CTM-loss in efficiency of only 0.5% absolute.