As the rapid rise of large silicon wafer formats over the past year has demonstrated, advances in one area of photovoltaic systems often impose new demands on another. At present, anti-reflective coatings (ARCs) have been widely used in the module production of front glass panels. The use of this technology also presents a new challenge to the concept of series and multi-junction batteries. Series and multijunction cells absorb a larger range of the solar spectrum and produce a larger range of reflections, which means that anti-reflective coatings (ARCs) need to reduce reflections over a larger range. Scientists at politecnica Madrid are seeking a solution to this problem by studying the role of antireflective coatings in the III-V multi-junction battery concept, especially in niche applications such as satellite power supply and space exploration. All their work is published in the journal Solar Energy, on high and low refractive index laminations of broad wavelength anti-reflective coatings for multijunction solar cells.
In the paper, the team points out that the latest methods of improving antireflective coatings currently include :(1) adding additional layers to the coating; (2) Use complex nanostructures or plasmas to make coatings -- all of which add complexity and material consumption to the manufacturing process.
With this in mind, the scientists insisted on using a thin double layer of alternating high and low refractive index materials to make the anti-reflective coating. The team also developed an algorithm to calculate the optimal coating design for two different types of III-V solar cells and demonstrated that a combination of high and low refractive index coatings can significantly improve cell efficiency.
In the simulation experiments of various battery technologies, the efficiency of coating design by using the above methods has been improved by 1-5%. The team also pointed out several potential advantages for mass production of the "high and low refractive index lamination" technique over existing anti-reflective coating treatments for multi-junction solar cells, which is said to have been used by other industries to produce glass coatings that can be adapted for current pv manufacturing.
The advantage of HLIS ARC is that it uses only two materials, compared with a multi-layer anti-reflective coating with a gradient base (e.g. HLIS ARC reduces the need for new materials compared to three or four anti-reflective coatings, "the scientists concluded." This technical solution is very simple, and the fact that high and low refractive index laminates do not seem sensitive to small changes in base thickness makes them more promising for practical applications."