Journal of Solar Energy Research
Volume:8 Issue: 1, Winter 2023

Photovoltaic systems are one of the types of solar power generation systems. One of the main issues for the construction of a photovoltaic power plant is to determine the type of solar panel installation structure to produce the maximum energy of the photovoltaic system. Most photovoltaic panels used around the world are at a fixed angle. To increase power generation, we can use solar Trackers that guide the panels in the direction of the sun, and with this technique, we can make the most of photovoltaic systems. In this paper, a 20 kW photovoltaic power plant is simulated to compare the power generation of a system with a fixed-angle panel and a system with a two-axis solar tracker. The purpose of this study is to determine to what extent more effective but more expensive tracking systems can be a suitable standard in future PV power plants in the country, it is also discussed the application of these systems when the area and number of modules are limited and this is if These cases have not been seen in previous studies. Simulations for the city of Tehran in Iran have been done with PVsyst software. The total energy produced annually by photovoltaic systems with two-axis solar trackers was more than the energy produced by fixed-angle panels. Also, the economic analysis of the power plant has been done with RETScreen software, which shows that the efficiency and output power of the solar system with a two-axis tracker has increased compared to the fixed system. Using solar tracking systems is complex and expensive, but we can have the same amount of energy with fewer solar modules than with fixed systems. Therefore, systems with two-axis trackers are more practical when using the minimum installation area required.

The main challenge of photovoltaic (PV) systems is to extract the maximum power from the array, especially when it is partially shaded and subjected to variable weather conditions (sunshine and temperature). To address this challenge, this manuscript proposes a new method based on the Neuro-Fuzzy- Particle Swarm Optimization (NF-PSO) combination. The NF method is used here because it allows an automatic generation of fuzzy rules, and we inject the PSO meta-heuristic at the input of the Neuro-fuzzy to find an optimal gain allowing not only to convert the real input values into fuzzy quantities and to readjust the dynamics of the fuzzy rules by reducing the power losses (oscillations), this combination also provides a simple and robust MPPT scheme to manage efficiently the partial shading, and its convergence to the global maximum power point (GMPP) is independent of the initial conditions of the search process. To confirm the NF-PSO as a viable MPPT option a comprehensive evaluation is performed against two other methods, namely the cuckoo algorithm and the original Neuro-Fuzzy. The simulation results of the system confirmed the better performance of this method in terms of speed with a response time of 0.044s, efficiency with 99.94%, and especially in terms of oscillation reduction with practically a negligible oscillation rate compared to the NF and the Cuckoo algorithm.

Today, considering that the building sector accounts for approximately 30% of the total global energy consumption, the approach of the sustainable architecture model is more emphasized in this area. Windows, as one of the main building elements, play a crucial role in absorbing enough daylight to improve interior space quality and to reduce energy consumption. Therefore, this study aims to design the window optimally considering four window variables, including window-to-floor ratio (WFR), as well as the position and shape of windows in the north and south façades of residential areas in Isfahan City. Finally, the findings indicate the impact of each parameter on daylight and energy consumption by simulating it in the DesignBuilder software. For example, a window with 50% WFR and rectangular shape (ratio of 1:1.5) at the top position of the south façade has optimal conditions in terms of static daylight metrics; however, the same window position at the bottom and middle of the façade will not have acceptable conditions in terms of the metrics. Obviously, other scenarios are not exempt from this rule, and it is complicated to select an optimal model. Consequently, by considering several metrics and evaluating them, it can be claimed that a rectangular window with 40% WFR in the south façade with a ratio of 1:2 at the top position of the façade can provide the optimum model in terms of suitable daylight and energy saving for a residential space in Isfahan and the general requirements of daylighting of the National Building Regulations should be examined considering the proposed glazing to floor ratio and the climate of each region.

The upward increases in electricity consumption in the last decade and excessive use of electricity in these years have challenged the electricity industry and related industries. The blackout caused by this increase in consumption leads to losses for manufacturing companies and workshops. The location of Hormozgan province has created this mentality for researchers that due to high humidity and dust, it is not possible to use PV power plants. The possibility of installing a 4 MW PV power plant in Industrial Estate No 2, has been investigated, and the simulation results with PVSol, PVSyst, and RETScreen software have shown that the location is a suitable place to install the power plant, and there is a possibility of obtaining suitable energy and supporting the industrial estate. In the selected position, it is possible to get suitable solar energy for more than eight months of the year, and solar energy could be used for more than 10 hours a day. The output of the simulations also showed that the construction of the PV power plant in this location with a performance factor of 0.7 and an average output power of 3.2 MW would be good efficiency. Since the hours of solar energy production correspond to the electricity peak hours of consumption, the PV power plant can be used as a suitable alternative for producing stable electricity and preventing power outages during peak hours of production units and factories. The use and comparison between south-facing panels and delta wing and the use of these types of equipment in the hot and humid climatic conditions of Hormozgan province have been done for the first time in this research.

Generally, optimal fixed orientation of PV modules is supposed to be the one that receives maximum solar energy. To receive maximum energy, tilt angle is typically set on the latitude angle of the installation site and the module orients toward the south axis of earth. In other words, it is assumed that if the module orients toward the maximum point of solar energy absorption, maximum electrical energy is generated and maximum fossil fuel pollutants emitted from one sample thermal power plant to generate the equivalent electricity is saved. PV system orientation angle accuracy has the potential to avoid tonnes of GHG emissions without any investment, operation and maintenance costs. If the module is not placed in the proper orientation, the emitted pollutants of the sample plant would not be maximum. In this research, fuel type and efficiency of sample plants are considered as the prime factors in determining the optimal orientation.  The paper aims to show that the proper orientation for maximizing saved CO2 emissions of thermal power plants is not equal to the orientation of maximum radiation and the related tilt and azimuth angles are different.

The present study proposes modified solar-driven combined power and ejector refrigeration cycles (CPERCs) for low-temperature heat sources. The proposed cycles are constructed from a combination of simple organic Rankine cycle (ORC), ORC with an internal heat exchanger (IHE), a regenerative ORC, and a regenerative ORC with an IHE, with an ejector refrigeration cycle (ERC). The ejector is driven by the exhausts from the turbine to produce more power and refrigeration, simultaneously. The three modified ORCs are introduced to improve the performance of the energy systems. The first and second laws of thermodynamics have been applied to each cycle using R245fa and isobutene as working fluids. Also, solar energy is utilized as the main heat source of the energy system. Concerning each proposed cycle, the thermodynamic model has been validated by previous works. Using isobutene as a working fluid, the maximum thermal and exergetic efficiencies have been obtained at 50.46 and 58.08 %, respectively, which corresponded to regenerative combined power and ejector refrigeration cycle with an IHE. In general, the thermal efficiency of a system is improved by 7.54 and 5.76 % through this state-of-art modification using R245fa and isobutene as working fluids, respectively. This demonstrated that isobutene can be a good candidate for CPERCs based on the first and second laws of thermodynamics. Throughout these modifications, cooling capacity and net produced power of cycles are also increased, successively. In all proposed cycles, the generator has the highest exergy destruction ratio, falling into the range of (29.82-34.73) and (22.9-25.93) kW for R245fa and isobutene, respectively.

With regard to the sustainability of using carbon dioxide in supercritical processes, this study proposes a novel power/hydrogen cogeneration arrangement consisting of a recompression supercritical carbon dioxide gas turbine cycle and a solid oxide water electrolysis unit in integration with a high-temperature solar-based heliostat field. The steady operation of the system is also guaranteed by means of thermal energy storage tanks. On this path, a numerical multi-variable study and optimization of the entire system are conducted. Hence, four main parameters are viewed to study the sensitivity of the net power output, hydrogen output, energy and exergy efficiencies, and unit cost of products. Hence, a genetic algorithm is applied to investigate the optimum conditions of the entire system considering the maximum energy and exergy efficiencies and the minimum unit cost of products as objective functions. Looking at the results, the sensitivity of the outcomes is further affected by the increase in compressor 1 inlet pressure. Besides, the optimum energy efficiency is 26.81%, optimum exergy efficiency is 21.03%, and optimum unit cost of products is 18.79 $/GJ are attainable.

The most important loss mechanism in single junction solar cells is the inability to convert photons with energies below the bandgap to electricity. Due to quantum confinement, graphene-based quantum dots (QDs) provide a means to create an intermediate band (IB) in the bandgap of semiconductors to absorb sub-bandgap photons. In this work, we introduce a new type-I core/shell-graphene/Si QD for use in all Si-based intermediate band solar cells (IBSCs). Slater-Koster Tight-Binding method is exploited to compute the ground state and the band structure of the graphene/Si QD. The ground state is obtained 0.6 eV above the valance band (VB), which is suitable for creating IB between the conduction band and VB of Si. A superlattice (SL) of this QD is created and the mini-band formation in SL is investigated by varying the inter-dot spacing between QDs. A mini-band with roughly 0.3 eV bandgap is observed in the well-aligned and closely packed SL. This SL is embedded in the intrinsic region of the conventional Si-based solar cell. The mini-band in SL works as an IB in the solar cell and results in increased photon absorption. As a result, carrier generation rate improves from 1.48943×1028 m-3s-1 to 7.94192×1028 m-3s-1 and short circuit current density increases from 211.465 A/m2 to 364.19 A/m2.

Because of the commitment between the large-scale photovoltaic power plants and the main grid to cope with different low voltage conditions in the grid, Low Voltage Ride Through (LVRT) capability of such plants is necessary. Handling this situation is more challenging when the main grid is under unbalanced conditions.  In this paper, a new LVRT approach is proposed to reduce oscillations in this situation. To this end, the simultaneous positive, negative, and zero sequences control (PNZSC) method is proposed to provide a suitable reference current for eliminating oscillations of the active power, and similarly to reduce voltage oscillations of the DC side. The zero sequence control is achieved through proper inverter switching.Also, this method limits the inverter output current to the maximum rated value. A Dual Second Order Generalized Integrator - Frequency Locked Loop (DSOGI-FLL) is used for better synchronizing of the inverter to the grid, in asymmetric faults. Besides, an interleaved DC-DC converter and a Neutral Point Clamped (NPC) Inverter are used to reduce Total Harmonic Distortion (THD) and losses. The performance of the proposed approach is confirmed using simulation of different possible scenarios in MATLAB/Simulink environment.

Since Iran has an average of 256 sunny days a year, solar energy in Iran can be used on a large scale. There are many mathematical models for measuring radiation on the surface, but choosing the best model can help measurement accuracy. In this article, first, direct and diffused radiation in Shiraz, Isfahan, Kerman, and Yazd, which are the central cities of Iran, has been calculated. The calculation has been done using the NRI model in MATLAB software. The powers received from this bench are computed in each city and their maximum efficiency is shown. The mentioned solar bench was built with a fixed angle. By comparing the efficiency between the mentioned cities, we identified the city with the most suitable place for building this solar bench. In Kerman, we can receive the highest amount of power throughout the year by using the optimum angle which measured. Due to the location of this city, it was expected to have the highest amount. This article examines the technical methods of using solar systems in urban architecture, emphasizing integration methods. The proposed and implemented model of the solar tree has the options to adjust the optimal angle and beautify passages, parks, and recreation centers. All these features make it useful to charge electronic equipment such as mobile phones, tablets, and electric bicycles through clean solar energy.