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A research group from Canada has optimized the performance of concentrator photovoltaic modules using so-called surface mounting technology for thermal management. The prototype CPV module uses four non-interconnected germanium III-V cells, a Fresnel lens, and a transparent glass printed circuit board.
Scientists from the University of Sherbrooke (Canada) have manufactured a prototype of a concentrator photovoltaic (CPV) module based on the so-called surface mount technology (SMT), a technique that is commonly used to mount electronic components on the surface of a printed circuit board (PCB).
The proposed SMT design does not use any bonding wire for cell emitter connection and aims to increase heat dissipation in the CPV panel, which in turn reduces its operating temperature and increases its performance.
“SMT, which uses a conductive solder paste for interconnection, has the advantage of being less expensive and faster for large-scale production, and SMT equipment takes up less space than cable-based wiring equipment,” they explained. . “We have developed and employed the SMT process, which integrates mounting flexibility and improved solar cell alignment, to assemble solar cells larger than one millimeter in size.”
The prototype 4-cell CPV module uses a Fresnel lens to focus light onto cells soldered to a clear glass printed circuit board and protected by layers of lamination. The emitter contacts are soldered via conductive solder joints to a glass printed circuit board, which incorporates metal tracks for the unsoldered areas. A transparent filler fills the gap between the solar cell and the printed circuit board to prevent reflections at the module bottom plate interfaces.
“The filler fillets protect the sides of the solar cell to avoid short circuits and contribute to the thermomechanical stability of the assembly,” states the research team. “The back side of the assembly is laminated with an EVA encapsulant and a Tedlar protective sheet to preserve the solar cells from the environment.”
The four cells used in the device are not interconnected with each other and are triple-junction germanium III-V solar cells, each with an active surface area of ??8,751 mm2. The cost of solar cells based on composites of element III-V materials, named after the groups of the periodic table to which they belong, has confined the devices to niche applications, such as drones and satellites. These are applications where low weight and high efficiency are more pressing concerns than costs.
The scientists mounted the 4-cell SMT CPV module on a 2-axis solar tracker on the Helios platform at the University of Sherbrooke.
The group performed a series of electrical and temperature measurements of the system under real operating conditions and also carried out a series of simulations based on finite element modeling (FEM), which is a numerical technique used to perform finite element analysis. (AEF) of physical phenomena.
Through their analysis and experiments, the scholars discovered that the dimensions of the metal tape on the back of each cell and the metal coverage ratio of the printed circuit board are key factors for the thermal management of the CPV module, while The other components have a negligible impact on the module temperature.
“The temperature of the solar cell can be maintained below 80 C over a wide range of dimensions of the metal strip behind the solar cell, for both 0% and 100% PCB metal coverage,” they further explained. . “However, this dimensional range is much wider when the metal coverage ratio is 100% than when the PCB metal coverage ratio is 0%.” The simulation also showed that the temperature of solar cells can reach 54 C with copper tape and 57 C with aluminum tape.
The system is described in the article “ Finite element modeling and experimental validation of concentrator photovoltaic module based on surface Mount technology ,” published in Solar Energy Materials and Solar. Cells . “These results demonstrate that, in addition to simplifying the assembly process, the use of SMT for the manufacture of CPV modules can improve heat dissipation both through the metal layer of the glass printed circuit board and through the contact of the face. later,” the researchers conclude. “This opens the door to simpler CPV modules, higher performance CPV modules and higher concentration ratios.” |
