3D-printed external light trap for solar cells

A New Type of Architecture of Dye-Sensitized Solar Cells as an Alternative Pathway to Outdoor Photovoltaics

The current investigation shows a possible new pathway for more efficient and cost-effective energy-harvesting photovoltaic devices. Our approach could permit all emerging technologies that are currently used for indoors and smart buildings to go a step forward and could be used for outdoor applications. The investigated architecture is a very promising geometry especially for Dye-Sensitized Solar Cells (DSSCs). It turns their main drawback, the lowering of their efficiency and lifetime when operating at high solar irradiation density, into an asset by increasing the total active area per horizontal unit area for light harvesting, while preserving the active elements from degradation and extending durable lifetime. The investigated architecture is based on a symmetric “U” type geometry, which is constructed by a highly reflective material on the inner surface. Solar irradiation is reflected internally at the bottom of the construction and splits towards two opposite sided solar cells; the two cells form a cavity where the solar light multiplies and is successively absorbed. Consequently, the vertically incoming irradiation is reduced when reaching the vertical internal sides on which the DSSCs are mounted. Thus, the solar cells operate at low light intensities, which provide significant lifetime extension and efficiency enhancement. Interestingly, the electrical energy per effective surface unit, which is produced by the two vertical DSSCs, is at least equal to that of a standalone, vertically irradiated cell. The advantage of the new architecture is that protects DSSCs from their degradation and deterioration, although the entire system operates under high illumination. This makes the cells more efficient outdoors, with a comparable performance to indoor conditions.

Additive Manufacturing: Unlocking the Evolution of Energy Materials

The global energy infrastructure is undergoing a drastic transformation towards renewable energy, posing huge challenges on the energy materials research, development and manufacturing. Additive manufacturing has shown its promise to change the way how future energy system can be designed and delivered. It offers capability in manufacturing complex 3D structures, with near-complete design freedom and high sustainability due to minimal use of materials and toxic chemicals. Recent literatures have reported that additive manufacturing could unlock the evolution of energy materials and chemistries with unprecedented performance in the way that could never be achieved by conventional manufacturing techniques. This comprehensive review will fill the gap in communicating on recent breakthroughs in additive manufacturing for energy material and device applications. It will underpin the discoveries on what 3D functional energy structures can be created without design constraints, which bespoke energy materials could be additively manufactured with customised solutions, and how the additively manufactured devices could be integrated into energy systems. This review will also highlight emerging and important applications in energy additive manufacturing, including fuel cells, batteries, hydrogen, solar cell as well as carbon capture and storage.

Spectral Response of Polycrystalline Silicon Photovoltaic Cells under Real-Use Conditions

The standard test conditions for photovoltaic modules are not capable of reproducing the environmental variations to which the modules are subjected under real operating conditions. The objective of this experimental work is to be an initial study on how the electric energy generation of photovoltaic cells varies according to the different wavelength ranges of the solar light spectrum under real operating conditions. Two modules were installed outdoors; color filters, which allow the passage of light at specific wavelengths, were installed on one of them. The amount of energy produced by the module with the filter was compared to the reference module, and the relative efficiency of each filter was defined. As a result, it was found that crystalline silicon modules do not respond uniformly to sunlight, being more sensitive to the red band (relative efficiency of 23.83%) and less sensitive to the green band (19.15%). The infrared contributes to a significant portion of energy production (relative efficiency of 13.56%), overcoming its negative effect of reducing energy generation capacity due to high photovoltaic cell temperature.

Exploration of external light trapping for photovoltaic modules

The reflection of incident sunlight by photovoltaic modules prevents them from reaching their theoretical energy conversion limit. We explore the effectiveness of a universal external light trap that can tackle this reflection loss. A unique feature of external light traps is their capability to simultaneously recycle various broadband sources of reflection on the module level, such as the reflection from the metal front grid, the front interfaces, the reflective backside of the cell, and the white back sheet. The reflected light is recycled in the space between the solar cell and a mirror above the solar cell. A concentrator funnels the light into this cage through a small aperture in the mirror. As a proof-of-principle experiment, a significant reflectance reduction of a bare crystalline silicon (c-Si) photodiode is demonstrated. In contrast to conventional light trapping methods, external light trapping does not induce any damage to the active solar cell material. Moreover, this is a universally applicable technology that enables the use of thin and planar solar cells of superior electrical quality that were so far hindered by limited optical absorption. We considered several trap designs and identified fabrication issues. A series of prototype millimeter-scale external metal light traps were milled and applied on an untextured c-Si photodiode, which is used as a model for future thin solar cells. We determined the concentrator transmittance and analyzed the effect of both the concentration factor and cage height on the absorptance and spatial intensity distribution on the surface of the solar cell. This relatively simple and comprehensive light management solution can be a promising candidate for highly efficient solar modules using thin c-Si solar cells.