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RICE experts ensure greater reliability of concentrated photovoltaic receivers

Scientists from the Regional Innovation Centre of Electrical engineering (RICE) at the Faculty of Electrical Engineering (FEL) have developed a new technology for creating advanced solar radiation receivers to use in concentrated photovoltaic systems. The experts have ensuree their higher performance, reliability and lifetime.

"At RICE, we are developing ceramic modules with a chip, the solar receiver itself, which are the core of the whole system," says Jan Řeboun of the innovation centre (RICE, UWB), which is involved in the international project ASES headed by the French company ERYMA. It deals with the production of camera and sensor security systems, for example for nuclear power plants, water reservoirs and similar facilities, often located in remote areas, for the supply of which it is necessary to provide an independent source of sustained power supply provided by renewable sources. In addition to UWB, three other entities are part of the consortium - the Spanish research institute TECNALIA, the BSQ company in Madrid and the Czech company ELCERAM to produce the ceramic modules.

Concentrated photovoltaics replaces the large-area silicon chip used in common solar cells with a 7x7-millimeter galia and arsenic-based chip placed only locally under a 25x25 cm optical lens that concentrates solar radiation for 820 times. Thanks to the solar radiation monitor, the panel with concentrated photovoltaics turns towards the sun, and the radiation always falls on the lens. The acceptor angle is further increased by the secondary optics, which reflects the sun's radiation so that it is directed exactly to the receiver. It is placed between the module and the main lens. "Silicon is a strategic and quite expensive material. Its replacement with optics brings both material and cost savings, " Jan Řeboun points out one of the advantages of concentrated photovoltaics. Another advantage is that it achieves double the efficiency compared to conventional photovoltaics, which, according to Jan Řeboun, is caused by using more sophisticated chips containing three photodiodes, each collecting a different spectrum of light. However, direct solar radiation is a precondition for efficient use of concentrated photovoltaics. The system is therefore particularly suited to areas with a large number of sunny days.

„Náš přínos je v nové technologii výroby modulů – jak samotného jádra, tak jeho montáže na keramickou destičku. Protože v systémech koncentrované fotovoltaiky se do jednoho malého místa soustředí velké množství energie, museli jsme zajistit dokonalé elektrické propojení čipu s destičkou a jeho vynikající chlazení,“ vysvětluje Jan Řeboun. Stabilitu systému dosáhli vědci tak, že destičku, na níž je umístěn čip, potisknou měděnou pastou a vypálí v inertní atmosféře. Měď je přitom pouze na místech, kde je žádoucí, a v tloušťce, která je zapotřebí k odvodu tepla. „Spojení je daleko pevnější a stabilnější než dosud používané technologie, a to i při velkých změnách teplot,“ vysvětluje Jan Řeboun, proč systém vyvinutý v RICE zvyšuje efektivitu a spolehlivost fotovoltaických čipů.

"Our contribution is in the new module manufacturing technology - both the core itself and its mounting on a ceramic plate. Because concentrated solar photovoltaic systems concentrate a lot of energy in one small place, we had to ensure a perfect electrical connection of the chip and the plate and its excellent cooling, "explains Jan Řeboun. Stability of the system has been achieved by scientists by printing a copper paste on the plate with the chip and burning in the inert atmosphere. Copper is only in places where it is desirable and in the thickness that is needed to remove the heat. "The connection is far more firmer and stable than the technology used, even at high temperature changes," explains Jan Řeboun why the RICE-developed system increases the efficiency and reliability of photovoltaic chips.

Since the end of February , the entire RICE solar receiver panel is placed on the roof of the Faculty of Electrical Engineering, University of West Bohemia, for testing. Testing also takes place with other members of the consortium. Testing at UWB will last at least until the end of May.