Increasing light capture in silicon solar cells with encapsulants incorporating air prisms to reduce metallic contact losses

Abstract

Silicon solar cells are the most widely deployed modules owing to their low-cost manufacture, large market, and suitable efficiencies for residential and commercial use. Methods to increase their solar energy collection must be easily integrated into module fabrication. We perform a theoretical and experimental study on the light collection properties of an encapsulant that incorporates a periodic array of air prisms, which overlay the metallic front contacts of silicon solar cells. We show that the light collection efficiency induced by the encapsulant depends on both the shape of the prisms and angle of incidence of incoming light. We elucidate the changes in collection efficiency in terms of the ray paths and reflection mechanisms in the encapsulant. We fabricated the encapsulant from a commercial silicone and studied the change in the external quantum efficiency (EQE) on an encapsulated, standard silicon solar cell. We observe efficiency enhancements, as compared to a uniform encapsulant, over the visible to near infrared region for a range of incident angles. This work demonstrates exactly how a periodic air prism architecture increases light collection, and how it may be designed to maximize light collection over the widest range of incident angles.

Finding 10% hidden electricity in crystalline Si solar cells using PDMS coating and three‐dimensional cell arrays

“…Although the encapsulation film shows some optical gain due to internal reflection of scattered light from the surface of the textured solar cells, it causes a large amount of optical loss by cutting off short wavelength light. Furthermore, by absorption of high energy short wavelength light, it suffers from a browning effect during long operation periods . In addition, the flat panel structures are only designed for standard characterization conditions, which do not fully reflect actual operation conditions, especially when they are used in urban applications.…”

“…Furthermore, by absorption of high energy short wavelength light, it suffers from a browning effect during long operation periods. 17,18,[25][26][27][28][29][30][31] In addition, the flat panel structures are only designed for standard characterization conditions, which do not fully reflect actual operation conditions, especially when they are used in urban applications. We suggest a new concept to overcome these limitations.…”

Omni-direction PERC solar cells harnessing periodic locally focused light incident through patterned PDMS encapsulation

“…Control over the microscopic light intensity within the solar cell device can allow control over the generation rate and excess charge carrier concentration. Recently, silicone-based encapsulation methods have been proposed as they overcome the efficiency losses that result from conventional encapsulation materials [16][17][18][19][20][21][22] such as ethylene vinyl acetate (EVA)-glass or EVApolymer lms that attenuate short-wavelength light. [23][24][25][26] Optical geometries that modify the light distribution across solar cells can be easily patterned into the encapsulating material during casting.…”

Microchannel contacting of crystalline silicon solar cells

“…However, these approaches still suffer from relatively modest aspect-ratios and are only effective on certain surfaces. One interesting approach to contact formation, with limited development within the field of c-Si PV 10 – 13 , is the use of microchannels as a template to define the contacts. Within the broader scientific community microchannels have been widely utilized, most prominently in the fabrication of biomedical and lab-on-a-chip type microfluidic devices 14 – 17 .…”