Comparison of Ribbon Light Management Designs for Photovoltaic Modules
Yang Li1, Ning Song1, Pei-Chieh Hsiao1, Mreedula Mungra1, Zi Ouyang1, Ingrid Haedrich2, Marco Ernst2, Bonna Newman3, Mark Jansen3, Chen Zhu4, Jun Lv4,5,1, Alison Lennon1
1UNSW Sydney, Sydney, Australia
/2Australian National University, Canberra, Australia
/3ECN part of TNO, Amsterdam, Netherlands
/4LONGi Solar Technology Co., Ltd., Xi’an, China
/5Electronic information engineering college of Sanjiang University, Nanjing, China

As solar cell efficiency approaches its theoretical limit, it is becoming increasingly challenging to further enhance the light management for cells. As a result, there has been increasing interest in improving the light management of solar modules to further enhance module power and electricity yield. Recently, several light management designs for interconnection ribbons have been proposed to reduce the optical loss arising from the front busbar shading.
In this work, examples of light scattering film (LSF), light scattering ribbon (LSR) and light diverting ribbon (LDR) currently available on the market are analysed and compared. The LSF and LSR scatter the incident light to the front surface of the glass, from where it is internally reflected back to the solar cell surface. While LDR works by redirecting the incident light to the cell surface directly.
With a new methodology based on the Angular Matrix Framework, the angular current gain and annual yield gain are simulated to compare the performance of modules with different ribbon designs. First, all three designs get similar current enhancement of 2.5% for normal incident light, which then declines as incident angle increases. Annual yield gain is also simulated and compared for installations at different latitudes considering realistic working conditions with varying incident angle, spectrum and direct/diffuse components. However, the annual yield gain of LDR doubles that of well aligned LSF and LSR due to its wider effective angular range for incident light, which is determined by the diverting working principle of LDR rather than the internal reflection of LSF and LSR. Finally, an angular correcting parameter of current is suggested for manufacturers to provide to help their clients estimate more accurately the performance of modules with advanced light management structures in real, outdoor operating conditions.