In this study, pure phase nanostructured strontium-doped lanthanum manganite, La0.75Sr0.25MnO3 (LSM), with a hexagonal structure was synthesized by sonochemical method. Then, XRD and SEM estimated the size of the LSM nanopowders. The results are exhibited that products synthesized in this method are compatible with particle size and morphology. Magnetic measurement was done by vibrating sample measurement (VSM) on LSM nanoparticles at room temperature. According to the results obtained from VSM displayed the saturation magnetization of LSM nanoparticles exhibited a maximum of 24.25 emu/g at room temperature. Then, the influence of LSM nanoparticle as an additive on the film morphology of CH3NH3PbI3 and the performance of perovskite solar cells was examined. We explore by using 5wt % of additive can increase the short current density (Jsc) from 14.45±0.55 to 18.29±0.38 mA/cm2 (~ 26.5 % enhancement) and power-conversion efficiency (PCE) from 8.33±0.40 to 12.41±0.35 (~ 49 % enhancement). Moreover, the morphology, and band gap of the new perovskite layer was improved.

The subject of this article is about the lifetime of solar devices consisting of number (n) of tubes. The solar energy devices, when they reach an aging stage, the tubes start to fail, the maintenance costs increase, and the production of the device decreases.The costs of solar energy device maintenance companies increase as the device gets old. Therefore, maintenance companies are looking for the age to replace the device with a new device. In this article, we searched for the best age to replace device (in aging stage) with a new device.By relying on strategy of balance the costs of tubes failure in unexpected time, we have determined the optimum time for preventive replacement of solar energy device. Then we studied the factors that influence the optimum time for preventive replacement of solar energy device.

The flat plate collector is the most famous and simplest type of solar collectors that is used as a water heater. In this study, a solar flat plate collector with triangular geometry and with zigzag and non-riser tubes was experimentally examined. To assess the collector, the ASHRAE standard was used in hot and dry climate conditions. The test site was located in southwestern Iran and was tested in the early months from March to June 2020. The measured parameters include the environmental and thermal parameters of the collector and the fluid, and the best data have been selected and presented. The results of the study showed that the collector had a suitable efficiency; the lowest recorded value was 32% and the highest was 58.9 %. Hence, It could be used as a solar water heating system in both domestic and industrial sectors. In the pressure drop testing, the results showed that in all flow rates used, the pressure drop in the collector was less than 0.1 bar. Also, the performance of the collector was presented based on environmental variables such as temperature and radiation, as well as fluid variables such as input temperature and flow rate.

The output power, energy, and exergy efficiencies of gas turbines significantly decrease by rising ambient temperatures during the warm weather periods. The utilization of evaporative inlet cooling in gas turbine cycles increases its performance, which is extremely useful when trying to meet the increasing electrical power demands and offsetting shortages during peak load times, especially in these warm periods. With this mind the present study focuses on the thermodynamics of a gas turbine equipped with wet compression system and integrated with air-film blade cooling, to address the importance gas turbine efficiency. The results of the investigated basic and modified cycles presents that for a turbine inlet temperature of 1400 oC, an ambient temperature of 45 oC, and a relative humidity of 15%, adding an evaporative cooler to a simple gas turbine cycle leads to an approximate 21% increase in specific work, from 331 to 273.7 kJ/kg air, compared to the simple cycle. The exergy analysis indicates that the highest exergy destruction occurs in the combustion chamber, owing to the large temperature differences and the highly irreversible exothermic chemical reactions.

In this article- we study devices that derive energy from natural process (sun, wind, winter, soil, etc.) and that are replenished constantly such as fans generating electric power and solar energy devices. However, all devices are exposed to damage over time resulting in the accumulation of the damage caused by climatic fluctuations (Every geographical area is characterized by bad weather characteristics that leave damage to the device; like wind, rain and humidity) that lead to the failure of the device. These devices receive energy directly from nature in order to supply it to other systems (mechanical, electrical, etc.). A failure of the device reduces electrical-mechanical production. The companies manufacture renewable energy devices and export them to other countries in various geographical locations. The devices are used to provide electrical current in these countries. These companies seek to develop long-term protection plans against the device failure. A failed device becomes ineligible even for recycling in these companies. Therefore, the cost of the device failure and forced replacement becomes too expensive for these companies. Because of this, companies tend to find the optimal time to replace the device shortly before failure to reduce the cost of failure. In this experiment we study a device that is subject to shocks and calculate the optimal time for preventive replacement of a said device. As an example a solar energy device exposed to shocks resulting from climate fluctuations. We place this device in three different geographical locations (desert, tropical, and temperate), and calculate the optimal time for preventive replacement of the device. Finally, the results from these three locations are compared.

The aim of the present work is to make maximum use of environmental potentials in order to save energy consumption and increase the quality of comfort in residential space through the design of buildings in accordance with the cold climate in Iran. Also, providing part of the heat needs of the building under study by solar energy is another way to reduce energy consumption. According to studies, and despite the fact that Iran has a high potential to use solar energy, so far no studies have been conducted on the climatic design of residential villas in cold climates with the approach of using solar water heaters. Also, the study of six different solar technologies to find the optimal system and also the one-year dynamic analysis of the optimal system are other innovations of the present work. In the present work, initially, with the help of the recommendations provided by Climate Consultant 5.5 software, a residential villa has been designed in accordance with the cold climate of Iran. Then, using TSOL 5.5 software, six systems based on solar heating and boiler have been examined to meet the thermal needs of the villa. After finding the optimal heating system, a one-year dynamic analysis was performed on it. By examining the climatic parameters, the strategies needed to ensure the comfort of the residents were implemented on a psychometric chart. The orientation of the building, the depression in the ground, etc. were among the suggestions to make the design of the villa compatible with the climate. The results of reviewing six solar heating systems showed that the solar system, including a hybrid tank with an internal heat exchanger, with the lowest number of collectors, had the highest heat efficiency and was able to provide 41.5% of the annual heat required by the villa.

Efficiency reduction of photovoltaic cells caused by increasing temperature, is an important issue that restricts their use in the middle of the day especially in summer. A new cost-effective method to increase the solar cell efficiency is presented to alleviate the problem. A combination of 40 fiberglass small cells are used in the form of a panel to perform the experimental tests. Water is used as absorbent of heat to reduce high temperature effects on the panel and the test results show that the panel efficiency is increased using the suggested method by amount of at least 16.8%. A 300W halogen lamp is regarded as the light source throughout the experiments.

Solar power is a great potential of renewable energy to replace fossil fuel in the future. In recent years, new installed solar energy accounts for a very large proportion of the total renewable energy supplied to the load. However, the state of connecting large solar farms will affect the national power system stability and voltage quality in the local power system. Therefore, assessing impacts of solar farms on the power system is necessary to determine voltage stability, the limited capacity of solar power at each power system and the reliability of the power grid before and after solar power is installed. This study uses ETAP software to evaluate impacts of planned solar farms on the local power system in Hau Giang province in 2025. The simulation results show that the power system is stable in terms of power flow after solar farms operation, in which the system loss is significantly reduced. The voltages of the power system are not disturbed when the solar farms are available according to results of transient stability analysis. Power system reliability improves significantly after operating solar farms for specific loads. It is shown that SAIDI, SAIFI and CAIDI before and after solar farms are installed are 5,8524 and 4,9847 hours/customer/year respectively, 0,4134 and 0,3955 times/customer/year respectively and 14,157 and 12,602 hours/customer respectively. The results show that when 07 solar farms with total capacity of 265MW are put into operation, the solar farms have a positive impact on the power grid of Hau Giang province.

In this research, a single-phase multilevel inverter with a reduced number of switches and driver circuits is introduced for analysis in photovoltaic systems. The proposed multilevel inverter consists of two parts, basic circuit, and H-bridge, which are responsible for generating voltage levels and symmetry of voltage levels (positive and negative), respectively. The proposed basic circuit in this paper consists of six unidirectional switches and three input sources and doesn’t use any capacitors or diodes, which reduces the volume and complexity of the control system. In this paper, the seven-level proposed structure is simulated in the MATLAB/Simulink software and the utilized modulation to generate the output voltage levels is level shifted pulse width modulation. Moreover, photovoltaic systems are exploited to supply the proposed inverter’s input sources, which work with perturb and observe algorithm at the maximum power point. In the simulation section, the voltage, current, power waveforms of the photovoltaic system, and the voltage of the proposed inverter input sources are demonstrated, and the voltage and current waveforms of the inverter for different conditions such as radiation and modulation index change are given. Finally, to show the merits and features of the proposed topology, the inverter is compared with some recent symmetrical structures in terms of the number of components and the rated voltage of the switches.

In this study, the thermal performance of a tank-in-tank solar combisystem is dynamically simulated to investigate the effect of various parameters such as collector type and area, storage tank volume, building specifications, heat exchange terminal units, and climatic conditions on system performance. The results showed that by increasing the collector area, tank volume and thickness of wall insulation, the solar fraction increases. It was also found that the use of floor heating instead of a radiator system improves the system performance. The solar fraction using the evacuated tube solar collector is 2.3% higher than that using flat plate solar collector. The annual solar fraction of 45.6%, 63.4%, 41.2%, 34%, 57.3%, and 88.1% is obtained in Hot-Dry (Tehran), Hot-Dry (Yazd), Cold-Dry (Tabriz), Moderate-Humid (Rasht), Hot-semi Humid (Abadan), and Hot-Humid (Bandar Abbas), respectively. The environmental analysis indicates that using the proposed solar combisystem could save 2241.3 m³ natural gas and offsetting 4731.5 kg less CO2 emissions during a year. The life cycle cost analysis shows that the payback time of the proposed system for the economic conditions of Iran is 7 years.