Potential of Si Tandem Solar Cells for PV-Powered Vehicle Applications

PV-powered vehicle applications are very attractive for reducing CO₂ emission and creation of new market [1]. Development of high-efficiency (&gt; 30%) and low-cost solar cell modules is very important. Although Toyota Prius and Nissan eNV 200 demonstration cars installed with Sharp’s high-efficiency III-V 3-junction solar cell modules with an efficiency of more than 30% have demonstrated longer driving range of 26km/day average compared to 16km/day average for Sono Motors Sion installed with Si back contact solar cell modules with an efficiency of 21.5%, cost reduction of MJ solar cells is necessary for PV-powered vehicle applications. Development of Si tandem solar cells [2] is very promising for cost reduction.<br/>This paper compares analytical results for PV-powered installed with various solar cell modules and actual driving distance of the Toyota Prius demonstration car and Sono Motors Sion. In addition, analytical results for driving distance of PV-powered vehicles installed with various candidate Si tandem solar cells and multi-junction solar cells are shown in this paper.<br/>Solar cell module efficiency impact on driving distance of PV-powered vehicles was calculated. In the calculations, 4kWh/m²/day as solar irradiance, 3m²as module installation area and the charging system efficiency of 73.9% composing of cell temperature correction, maximum power point tracking, DC/DC conversion, and DC charging were assumed. Table 1 shows estimated potential and actual data for driving distance DD of vehicles powered by current solar cell modules. Good agreement between calculated and actual data shows validity of analytical procedure as shown Table 1. Table 2 shows estimated potential of driving distance DD of vehicles powered by candidate Si tandem solar cells including our results and multi-junction solar cells. The III-V 3-junction and Si 3-junction tandem solar cell modules with an efficiency of more than 35% are shown to have potential of driving distance of more than 30 km/day average and more than 50 km/day on a clear day as shown in Table 2.<br/><br/><b>Table 1</b>. Estimated potential and actual data for driving distance DD of vehicles powered by current solar cell modules<br/>Modules Efficiency (%) Estimated DD (km/day) Actual DD(km/day)<br/>III-V 3-J 32.65 27.0<br/>III-V 3-J (Prius) 30.9 25.6 25.6<br/>GaAs 25.1 20.8<br/>Si 24.4 20.2<br/>Si (Sion) 20 16.6 16<br/>CIGS 19.2 15.9<br/>Perovskite 17.9 14.8<br/><br/><b>Table 2</b>. Estimated potential of driving distance DD of vehicles powered by candidate solar cells<br/>Solar cells Efficiency (%) Estimated DD (km/day)<br/>III-V 3-J 39.5 32.8<br/>III-V/Si 3-J 35.9 29.8<br/>III-V/Si 3-J (our study) 34.0 28,2<br/>III-V/Si 2-J 32.8 27.9<br/>III-V/CiGS 3-J 29.3 24.3<br/>Perovskite/Si 2-J 29.8 24.7<br/>Perovskite/perovskite 2-J 28.0 23.2<br/>Perovskite/CIGS 2-J 24.2 20.1<br/><br/>Several losses such as non-radiative recombination, optical and resistance in Si tandem solar cells are discussed in this paper.<br/><br/><b>References</b><br/>[1] M. Yamaguchi et al., <i>Prog. Photovolt. </i><b>29,</b> 684 (2021).<br/>[2] M. Yamaguchi et al., <i>J. Phys. D: Appl. Phys</i>. <b>51</b>, 133002 (2018).<br/>[3] M. Yamaguchi et al., <i>J. Mater. Res. </i> <b>32</b>, 3445 (2017).