Enikő Bándy

Low cost solar irradiation sensor and its thermal behaviour

This paper presents the working principle, design and thermal characterization of an irradiation sensor. The irradiation measurement device must have accuracy and a reliable construction under outdoor use conditions. The sensor is based on a photoelectric cell and incorporates a read-out circuit for providing steady short circuit conditions for the cell as well as for signal amplification. Thermal tests (HTS, LTOL) were accomplished in a climate chamber in the temperature range of -20 to 80^oC in steps of 10^oC. To determine the fundamentals of the thermal dependence of the sensor cell spectral response measurements under varying temperatures were performed. Measurements show that the self-made solar cells thermal dependence was 0.26%^oC^-^1, revealing higher temperature dependence than in the case of an industrial reference cell.

Fabrication and characterization of microscale heat sinks

In the field of thermal management, engineers are well aware of the challenges posed by the increasing level of dissipation. Among the many possible solutions to counter the threat of overheating, one is dealing with the usage of microscale heat exchangers, where the forced air or liquid cooling solution is integrated into the electronic package itself. As the System-on-Package integration is not a straightforward task, many fabrication steps have to be fully developed before a successful chip-level cooling system is ready to be used. In this paper, as one of these many steps, we present a refined manufacturing technology which gives the possibility to create the microscale heatsink integrated together with the electronic devices. With the refined manufacturing technology several channel patterns can be created easily. Nevertheless, only a simple channel pattern is presented now which is tested with the enhanced thermal characterization method developed for microchannel based cooling structures last year.

Thermal behaviour of new crystalline semitransparent solar cell structure

This paper presents the structure of a novel semitransparent solar cell and its thermal behaviour, which cell can be used for building integrated applications. The crystalline self-made test cells can be manufactured using basic semiconductor technological steps, arbitrary pattern of holes can be etched. We report on two alternative methods for thermal behaviour characterisation of the novel semitransparent solar cell compared to non-transparent solar cells. The first method is thermal dependence and High Temperature Store (HTS)-condition A testing and the second is application of conventional thermal imaging in combination with electrical current heating of the solar cell. I-V characteristic measurements at preset temperatures demonstrate that the new semitransparent sample despite the throughout holes can be as effective as the without hole solar cell. IR imaging results reveal the localised resistive heating zones or shunting in the test cells. This research examines the influence of the through-holes on the thermal properties of solar cells.