Vertically-Stacked Photovoltaic/Bypass Diode Module With Improved Shadow Performance

Abstract

This letter presents a vertically-stacked photovoltaic (PV)/bypass diode (BPD) module fabricated via localized substrate removal and flip-chip assembly with the aim of improving shadow performance under Gaussian laser illumination. The proposed scheme also prevents the direct illumination of BPDs to eliminate reverse current leakage. The proposed PV/BPD module achieved output voltage (electrical power) of 4.24V (1.6 mW) in a small form factor (4.84 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), as well as a linear shadow response with -0.118 mW electrical power loss per shaded PV cell. Under laser misalignment conditions (>0.4 mm shift), the electrical power generated by the PV/BPD module was 2~4 times higher than that of a PV module without BPD. The fact that the PV and BPD chips can both be fabricated using foundry bulk CMOS processes facilitates the integration of the proposed module with sensor circuits and/or (super)capacitors to form a compact self-powered system.