Spectral effects on the energy harvesting efficiency of 2- and 4-terminal tandem photovoltaics

TL;DR

This study examines how spectral variations and top cell bandgap influence the energy yield of 2T and 4T perovskite/silicon tandem solar cells under real outdoor conditions, revealing that spectral deviations have minimal impact on efficiency.

Contribution

The paper introduces a spectral binning method for efficient environmental data analysis and compares the energy harvesting efficiency of 2T and 4T tandem devices considering spectral effects and realistic losses.

Findings

Spectral deviations reduce energy yield by only 2% for current-matched devices.

2T devices can match or outperform 4T devices when realistic losses are included.

Bandgap deviations over 0.1 eV decrease efficiency by more than 5% for 2T tandems.

Abstract

In this work, we investigate how a varying spectral irradiance and top cell bandgap affect the energy yield of 2T and 4T perovskite//silicon tandem solar cells under outdoor operating conditions. For the comparison, we first validate an optoelectronic model employing a 1-year outdoor data set for a 4T mechanical stacked GaAs on Silicon tandem device. We then use our verified model to simulate perovskite//silicon tandem devices with a varying perovskite top cell bandgap for a location in Golden, Colorado, USA. We introduce a spectral binning method to efficiently reduce and improve the visualization of the 1-min-resolved environmental data while maintaining the simulation accuracy. Our findings reveal that, for a device that is current-matched under standard testing conditions, the annual spectral deviation reduces the energy harvesting efficiency by only 2%$_\mathrm{rel}$. When additional realistic losses for the 4T are taken into account, 2T devices are shown to have an energy-harvesting efficiency that is at parity or higher. Deviations in the top cell bandgap of more than 0.1 eV from current matching result in a reduced energy-harvesting efficiency of more than 5%$_\mathrm{rel}$ for the 2T tandem device.