The most important energy source of the world is the sun. Solar energy can be converted to electricity by using photovoltaic (PV) solar panels. It is known that maximum electrical efficiency of PV solar panels is around 15%-20%. Therefore, it is clear that PV solar panels are not very efficient. This is due to some reasons. One of the most important of these reasons is the increase in the temperature of the PV solar panel. Therefore, PV solar panels should be cooled by means of any cooling methods. For this reason, in this study, the effect of temperature on electrical efficiency of PV solar panels has been investigated experimentally. For this purpose, an experimental setup, containing two PV solar panels with and without cooling, was installed. In this experimental setup, unlike the general literature a flowing water film, which is on the panel, obtains the cooling. It has been determined that power output of the cooled solar panel is greater than without cooling one. A 11.143 W electrical power has been gained from the PV panel due to cooling obtained by flowing water film. The average power increase by means of designed cooling system is about 9.51%. As a result, it was specified that the cooled solar panel was approximately 13.69% more efficient than the uncooled one. In this experimental study, uncertainty analysis was also performed. The uncertainty of the maximum power and electrical efficiency are ± 0.16130% and ± 1.28366%, respectively.

Poisson’s ratio is important mechanical property of materials and structure. Material and Structure showing negative Poisson’s ratios are called Auxetic. Properties of the Auxetic structures are very important to design the new structure, especially mechanical properties of the Auxetic materials that have structurally and functionally mission. Many researchers made experimental and theoretical works apropos this matter. In this study, the newly designed Auxetic lattice structure Poisson’s ratio was checked over via exploiting finite element analysis. 14 different lattice structures with respect to inner lattice thickness configurations are investigated. All examined structures have a negative Poisson’s ratio. Inner lattice thickness is increased; negative Poisson’s ratio values are decreased (closes to -1.) in these examined lattice structures. 4x2 lattice orientation has lowest Poisson’s ratio than 4x4 Lattice structure Poisson’s ratio, 4x2 is more Auxetic. 4.9 mm inner lattice thickness and 4x2 lattice matrix examined example has lowest Poisson’s ratio that is -0,55. Beneficial to indicate the purview of the structure on the applied force, the stiffness values and the stiffness/mass values were examined. Their energy dissipation capabilities were analyzed.