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J. Sol. Energy Eng. 2018;140(6):061001-061001-5. doi:10.1115/1.4039747.

This research document presents a new insulation material for solar thermal collectors. Tests were carried out in the laboratory, on an active solar energy demonstration system (ET 200), illuminated with a halogen lamp instead of sun. In this paper, the polystyrene used as insulation in the ET 200 flat plate solar collector was replaced by the cheaper natural material based on clay and straw. The polystyrene in the experimental device is placed under the absorber plate and along the edges of the casing containing the components of the solar collector. In this work, only the polystyrene of the four similar edges was replaced by the composite material. The use of the clay and straw as insulation material instead of polystyrene increased temperature difference (T2 − T1) between the inlet and the outlet of the absorber by 0.9±0.14 °C (p < 0.05); thus, increasing the useful power transmitted to water in the solar collector. Compared to polystyrene, tank water was well heated using the proposed material (p < 0.05). This latter also improved the performance of the solar collector by 5.77%. So, it is recommended to use the cheapest nonpolluting material based on clay and straw instead of synthetic insulation to improve the performance of the solar collector.

Commentary by Dr. Valentin Fuster
J. Sol. Energy Eng. 2018;140(6):061002-061002-7. doi:10.1115/1.4039776.

A street lamp with automatic solar tracking system can control the adjusting mechanism of azimuth and altitude so that the solar panel may adapt itself to the sunlight to improve the photoelectric conversion efficiency. In this work, we demonstrated the design of the adjusting mechanism of azimuth and altitude and verified the wind resistance. The method was realized by capturing the incident direction of sunlight using the photodiode array. The signal of the photodiode array can be processed by LM339N and then was sent to the single chip, which can deal with the signal to the motor of the adjusting mechanism of azimuth and the linear actuator of the adjusting mechanism of altitude, respectively. The hall sensors, embedded in the adjusting mechanism, are utilized to fulfill the feedback of the motion position to the single chip. These results clearly reveal the potential of the system in application.

J. Sol. Energy Eng. 2018;140(6):061003-061003-11. doi:10.1115/1.4039777.

This work is concerned with an experimental design for generating power from thermoelectric generator (TEG) and linear Fresnel lens collector with one-axis solar tracking system. Main purpose of this experimental design is to measure the performance of the TEG with linear Fresnel lens collector. This work also aims to create a mathematical model by using adaptive neuro fuzzy inference system (ANFIS) model so that the electrical production estimates of the constructed system can be made for a given data set. For this reason, two individual systems, selective surface adapted for achieving medium temperature scale and nonselective surface for low temperatures, were constructed. There are two different coolant systems, which are passive and active, to create effective open circuit voltage values. Experimental results show that the maximum open circuit voltages were obtained as 0.442 V and 1.413 V for experimental system with selective surface adapted, as 0.341 V and 0.942 V with nonselective surface adapted when the received radiated power on Fresnel lens was measured nearly 625 W/m2 on average in the noon time. Experimental values were collected for the selective surface adapted system on 11th and 12th of September, 2017 and for nonselective surface on 13th of September, 2017, respectively, in Samsun/Turkey with location 41°14′N and 36°26′E. The collected data such as solar irradiation, wind speed, ambiance temperature, and open circuit voltage were used for (ANFIS) modeling. Obtained result shows that experimental calculations and modeling are consistent with each other.

Commentary by Dr. Valentin Fuster

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