Micro-concentrators for a microsystems-enabled photovoltaic system

The reflection of incident sunlight prevents photovoltaic modules from reaching their full energy conversion potential. Recently, we demonstrated significant absorption enhancement in various solar cells by external light trapping, using 3D-printed and milled light traps. In order to facilitate direct module integration, we introduce an external light trapping design concept tackling the reflection issues at the module level. In this module design, a lens array on the module cover glass funnels the incident sunlight through small apertures in a reflective coating at the backside of the cover glass. This adapted cover glass can be applied on a conventional module design. The reflector and the solar cells together form an optical cavity, in which most reflected light is recycled by directing the reflected light back to the solar cell. A unique feature of this light trapping module is its capability to simultaneously recycle the broadband reflection from the metal front grid, the front interfaces, the reflective backside of the cell, and the white back sheet. Moreover, it allows separate integration and contacting of low and high bandgap solar cells for highly efficient hybrid tandem modules that have no current matching related losses. We show five module designs for improved light management combined with additional features such as color and image display. We discuss the optimal harvesting of the diffuse and direct component of the sunlight. The outlook of highly efficient, colored, and even image displaying modules makes this technology an interesting candidate for a new class of photovoltaic modules.

Section: Commonly Available Lensesmentioning

confidence: 99%

Concepts for external light trapping and its utilization in colored and image displaying photovoltaic modules

Dijk

Groep

Veldhuizen

et al. 2017

“…The SMT approach used in this study is one possible solution to this problem. (ii) High accuracy is required for the concentrator shape and alignment . This is especially true for higher concentration ratios, especially with a miniature Fresnel lens, in which prism edge must be sufficiently sharp to maintain concentration performance for a very small cell.…”

Section: Fabrication and Experimentsmentioning

confidence: 99%

Maximization of conversion efficiency based on global normal irradiance using hybrid concentrator photovoltaic architecture

Yamada

Hirai

2016

Maximization of module conversion efficiency based on global normal irradiance (GNI) rather than direct normal irradiance (DNI) was experimentally demonstrated using a hybrid concentrator photovoltaic (CPV) architecture in which a low-cost solar cell (a bifacial crystalline silicon cell) was integrated with a high-efficiency concentrator solar cell (III-V triple-junction cell) to harvest diffuse sunlight. The results of outdoor experiments showed that the low-cost cell enhanced the generated power by factors of 1.39 and 1.63 for high-DNI and midrange-DNI conditions, respectively, and that the resultant GNI-based module efficiencies were 32.7% and 25.6%, respectively.

“…Because the relative location of the light source (the Sun) changes with the rotation and revolution of the Earth, solar tracking systems are employed to align these optical concentrators and solar cells toward the Sun by precisely controlling the angle of the CPV panels, based on GPS or vision sensors . However, conventional solar trackers tend to be bulky and heavy, requiring dedicated installation or resistance to wind loading , and to address these issues, relatively thin and light planar‐type concentrators or waveguide systems have been developed to collect incident light onto the solar cells, usually with a compromise in the acceptance angle of light. More recent developments include a folded optical path , tracking integration , seasonal waveguide tracking , a kirigami structure , flexible structure or bio‐inspired structure for planar‐type concentrators.…”

Section: Main Textmentioning

confidence: 99%

Automated dual‐axis planar solar tracker with controllable vertical displacement for concentrating solar microcell arrays

Lim

Kwak

Song

et al. 2016

Concentrator photovoltaics are able to maintain power output for extended hours while reducing the quantity of expensive high performance compound semiconductor solar materials. One of the limitations in concentrator photovoltaics is the bulky and heavy form factors of solar tracking systems which usually require dedicated installation locations and resistance to wind loading. This paper describes a planar solar tracker that requires only micro or millimeter scale lateral and vertical displacements of a microlens array to maintain both the optimum lateral locations and focal lengths at various incident angles of light, using dual-axis actuations. Experimental results for lateral solar tracker were obtained under a solar simulator considering the effects of the rotation and revolution of the Earth, and under the Sun on a rooftop with the actual system, to demonstrate the concept and practical performance.