Efficiency Of Solar Power Plants Research Articles

Impact of variation of solar irradiance and temperature on the inverter output for grid connected photo voltaic (PV) system at different climate conditions

The main purpose of this paper is to observe the effect PV variation of solar temperature and irradiance on different conditions and on the inverter output for a grid-connected system. Majorly temperature& solar irradiation effects the performance of a grid connected inverter, also on the photo-voltaic (PV) electric system. Thesimulation basedstudy was carried out in order toevaluate the variation of inverter output with the variation of solar temperature and irradiance with the variation in climate. The analysis of Grid-connected inverter and their performance at various seasons and conditions is investigated. Solar power plantfor a year. In solar power plant efficiency of inverter is also considered to calculate overall losses so, the inverterefficiency and plant performance are considered in this paper using MAT Lab software. In summer season the inverter performed efficiency is decreased because of peak temperature value and slightly increased with the increase in irradiance.

An evaluation of the artificial neural network based on the estimation of daily average global solar radiation in the city of Surabaya

The estimation of the daily average global solar radiation is important since it increases the cost efficiency of solar power plant, especially in developing countries. Therefore, this study aims at developing a multi layer perceptron artificial neural network (ANN) to estimate the solar radiation in the city of Surabaya. To guide the study, seven (7) available meteorological parameters and the number of the month was applied as the input of network. The ANN was trained using five-years data of 2011-2015. Furthermore, the model was validated by calculating the mean average percentage error (MAPE) of the estimation for the years of 2016-2019. The results confirm that the aforementioned model is feasible to generate the estimation of daily average global solar radiation in Surabaya, indicated by MAPE of less than 15% for all testing years.

System for maintaining optimal temperature modes of solar power plants

Objectives: To ensure efficient operation of solar modules and temperature mode in accordance with standard test conditions range within 20-30◦C. Methods: A mathematical model was developed using the laws of photoelectricity, heat and mass transfer, which provides improvement in the efficiency of solar power plants. Findings: This study presents the theoretical analysis of different embodiment for systems of solar modules using physical and mathematical models. The main design and functional characteristics of solar modules were calculated: temperature and efficiency depending on internal parameters and ambient environment. Dependence between temperature and efficiency of solar modules for different values of air temperature, emissivity factor of solar cells, and efficiency of solar power plants, were determined and presented in the form of diagrams. It was found that solar modules have the highest heating temperature at solar irradiance of Еc=1200 W/m2, air temperature of Тa=50◦C, and that the solar modules have the lowest heating temperature at Тa=30◦C and e =0.8, with a decrease in the heating temperature from 111 to 38oС, the efficiency decreases at an air temperature of 50oС and at the emissivity factor of e =0.8 and 0.3 and makes from 4.2 to 10.3%. The dependences were calculated for different latitudes φ: 56o(Moscow), 45o(Krasnodar), 35.5o(Eslamshahr, Iran), 31.6o(Béchar, Algeria), 13.1o(Chennai, India). Solar modules with cooling devices were installed in the Istra district of the Moscow region and bench tests, to specific calculated parameters, were carried out under full-scale conditions. Conclusions: It was found that the efficiency of solar panels increased significantly due to the use of systems with heat-exchange tubes, and the losses, when using an antigravity heat exchanger for cooling photovoltaic cells, reduced by 6-7 times. Novelty: Usage of an anti-gravity heat exchanger to cool the photovoltaic cells, to maintain the optimal operating temperature prevent electrical distortion due to extreme temperatures. Keywords: Solar panels; air temperature; cooling; emissivity factor; solar irradiance; antigravity tubes; temperature loads; performance improvement

Improving the efficiency of the use of photovoltaic stations in the republic of Cuba

This article is devoted to the study of the reasons for the low efficiency of solar generators in the Republic of Cuba. The work provides one of the possible technical solutions to this problem. The introduction of new technological solutions requires an integrated approach that evaluates the possibility of applying more efficient technologies for capturing sunlight in specific climatic conditions of the country, as well as evaluating the economic benefits of a particular solution. Therefore, this article discusses the existing problem of low efficiency of solar power plants, due to the absence of any tracking systems for the sun. The paper presents ways to solve this problem. Also, the paper presents a model of a photovoltaic solar system generator developed in the Matlab Simulink software, which makes it possible to study the main electrical variables of the complex. The experience gained in the course of the study presented in this paper can be applied in similar studies in Russia.

Passive performance enhancement of parabolic trough solar concentrators using internal radiation heat shields

Boosting the optical and thermal efficiencies of parabolic trough concentrators is gaining renewal global interest for improving the overall concentrating solar power plant efficiency and reducing the specific costs of power generation. Using internal radiation heat shields in the annular space of the heat collection element is an attractive passive solution that is not well-addressed in the literature. This study is a first attempt to analyze and map both energetic and exergetic performances of parabolic trough concentrators in terms of the configuration of the radiation heat shield and the operating conditions of the concentrator. A 3D model based on Monte-Carlo ray tracing and computational fluid dynamics is developed, validated, and used to examine 420 combinations of design and operating parameters. The proposed design outperformed the conventional one in the whole spectrum of operating conditions, except for a narrow range of low operating temperatures and high flow rates. Floating radiation heat shields with small diameters and large shading angles enhanced the temperature uniformity of heat collection element and showed the highest enhancement ratios of both energy and exergy efficiencies, which were up to 15.4 and 14.4%, respectively. A radiation heat shield with a diameter of 75 mm and a shading angle of 150° was found the best performing configuration for most operating conditions. Increasing the shield’s emissivity (0.06) to that of the absorber tube (0.14) reduced the energy and exergy efficiencies by up to 33.75 and 29.06%, respectively. The effectiveness of the modified design was more pronounced at lower solar irradiance levels. The enhancements of energy and exergy efficiency decreased by 85.76 and 86.40% as the irradiance increased from 200 to 1000 W/m2. However, the modified design was still more efficient at all considered values of emissivity and solar irradiance.

Methods of calculating solar insolation for the assessment of energy efficiency of solar power plants

Methods of calculating solar insolation for the assessment of energy efficiency of solar power plants

Improving the Efficiency of Solar Power Plants

Introduction. An urgent scientific problem is to increase the efficiency of using solar energy in solar power plants (SES). The purpose of the article is to study methods for increasing the efficiency of solar power plants. Materials and Methods. Solar power plants based on modules with a two-sided working surface are considered. Most modern solar power plants use solar modules. The reflection of solar radiation from the earth’s surface provides an increase in the production of electrical energy by 20% compared with modules with a working surface on one side. It is possible to increase the efficiency of using solar energy by increasing the annual production of electric energy through the creation of equal conditions for the use of solar energy by the front and back surfaces of bilateral solar modules. Results. The article presents a solar power plant on a horizontal surface with a vertical arrangement of bilateral solar modules, a solar power station with a deviation of bilateral solar modules from a vertical position, and a solar power plant on the southern slope of the hill with an angle β of the slope to the horizon. The formulas for calculating the sizes of the solar energy reflectors in the meridian direction, the width of the solar energy reflectors, and the angle of inclination of the solar modules to the horizontal surface are given. The results of computer simulation of the parameters of a solar power plant operating in the vicinity of Luxor (Egypt) are presented. Discussion and Conclusion. It is shown that the power generation within the power range of 1 kW takes a peak value for vertically oriented two-sided solar modules with horizontal reflectors of sunlight at the installed capacity utilization factor of 0.45. At the same time, when the solar radiation becomes parallel to the plane of vertical solar modules, there is a decrease in the output of electricity. The proposed design allows equalizing and increasing the output of electricity during the maximum period of solar radiation. Vertically oriented modules are reliable and easy to use while saving space between modules.

Improving the energy efficiency of a solar power plant

The urgency of the work is due to the feasibility of increasing the energy efficiency of solar power plants through the use of solar energy concentrators. Ways to improve the energy efficiency of solar panels using a sys-tem of directional mirrors, flat Fresnel lenses, spherical concentrators and trackers have been investigated. It is established that the most optimal way to improve the energy efficiency of solar panels is to use inexpensive track-ers with a simple design. The analysis of known types of solar panels, which differ in materials from which their elements are made, and the coefficients of efficiency – dependence of energy produced by a photocell on the intensity of solar radiation per unit of its surface has been carried out, and the type of solar panels by the criterion “price-quality” has been selected. A tracker design has been developed to track the angle of inclination of solar panels to increase efficiency. The electricity generated by the proposed solar power plant was calculated using an online calculator. It is projected to reduce losses when generating electricity for a given power plant due to the use of a tracker compared to a fixed power system, with the same number of solar panels. In order to reduce the cost of the tracker, it is suggested to orientate it to the south at once, and to change the inclination angles twice a year (in early April and late August). The energy efficiency of the power plant is calculated in two stages. At the first stage the amount of electricity from solar panels per year when adjusting only the angle of inclination of the panels to the south is calculated. At the second stage energy efficiency of the power plant is calculated taking into account the increase of energy efficiency of the solar power plant when using the tracker system. The calculated electricity generation of the proposed solar power plant with tracker confirmed the efficiency and feasibility of using the designed tracker system. The application of the designed tracker system allows to increase the energy efficiency of solar panels by an average of 25%.

Energy and Exergy Analyses of an Existing Solar-Assisted Combined Cycle Power Plant

Solar-assisted combined cycle power plants (CCPPs) feature the advantages of renewable clean energy with efficient CCPPs. These power plants integrate a solar field with a CCPP. This integration increases the efficiency of solar power plants while decreasing the CO2 emissions of the CCPPs. In this paper, energy and exergy analyses were performed for an existing solar-assisted CCPP. The overall thermal efficiency and the exergetic efficiency of each component in the power plant were calculated for different solar field capacities. Also, a parametric study of the power plant was performed. The analysis indicated that the exergetic efficiency of the power plant components has its lowest value in the solar field while the condenser has the lowest exergetic efficiency in the combined cycle regime of operation. Further, a parametric study revealed that the thermal efficiency and the exergetic efficiency of the power plant as a whole decrease with increasing ambient temperature and have their highest values in the combined cycle regime of operation. Owing to these results, an investigation into the sources of exergy destruction in the solar field was conducted.

Principles of Building Systems with Concentrated Solar Energy

Design methods and mathematical models for calculating the characteristics of solar module concentrators with specified optical energy parameters have been developed and investigated. These parameters increase the efficiency of solar power plants operating both in a stationary mode and with a tracking system. Modules with parabolic concentrators, linear and cylindrical photodetectors were used in stationary and solar-tracking arrays. The basic structural and functional parameters of solar modules, the concentration and distribution of concentrated solar radiation over the focal spot width depending on the parametric angle based on the lower and upper parabolas were calculated using physical and mathematical models and derived universal analytical expressions. The given characteristics show possible variants of the dependence of the geometric concentration on the parametric angle of the concentrator for different values of the parameters of the universal analytical equation. The dependences of the geometric concentration on the parametric angle of parabolic concentrators are calculated for different values of the structural parameters: the profile of the module of two conjugate compound concentrators; the concentration distribution along the receiver from the upper and lower concentrators and the module as a whole; and the distribution of illumination along the lateral surface of a cylindrical solar radiation receiver. It is shown that the ratio of the experimental concentrations to the calculated characteristics agrees with the optical efficiency of the modules. The above calculation methods based on the principles of constructing systems with concentrated solar energy allow a comparative analysis of the parameters and the choice of the design of various types of concentrators for the solar modules being developed.

Sun tracking system for photovoltaic batteries in climatic conditions of the Republic of Cuba

Annotation. Today, the efficiency of solar power plants in the Republic of Cuba is low, despite the high level of technology development in this area. The article presents the results of the analysis of the potential of solar energy in the territory of the Republic of Cuba. This paper presents the results of experimental studies, the purpose of which is to increase the efficiency of using photovoltaic stations. The developed two-axis sun tracking system is described. This tracking system increases the conversion efficiency of solar energy into electrical energy in photovoltaic modules.

Efficiency of solar power plants in Bashkortostan

Efficiency of solar power plants in Bashkortostan

Method for Calculating the Capacity of Solar Power Plants and its Implementation in LabVIEW Environment

The paper presents the method for calculating the capacity of an autonomous solar power plant and its components. This method allows considering a load variation during the day as well as specifying the required capacity of the battery and excluding an unjustified overestimation of the power plant component capacities along with the increase in efficiency of the autonomous solar power plant. Formula for determining the required battery capacity of an autonomous solar power plant could be easily generalized for any number of changes in the load schedule steps. Virtual instruments (calculators) for calculating the capacity of an autonomous solar power plant and its components have been developed on the basis of this method in LabVIEW environment. These calculators may have a rather high visibility, ease of use and low memory requirements along with less computing time spent on calculations. The first calculator may allow recalculating capacities of loads on the power plant main supply bus as well as determining the energy consumption of loads per day. The second calculator may be used for determining the required capacity and number of batteries as well as the capacity of the charger, inverters, main supply bus and solar modules along with the solar power plant efficiency.

Выбор параметров и анализ эффективности применения систем слежения за Солнцем

Актуальность. Эффективным способом повышения производительности фотоэлектрических станций является применение систем слежения за положением Солнца. Ярко-выраженная зависимость величины солнечного излучения, поступающего на приемную поверхность солнечных батарей, от географического положения электростанции и климатических условий обуславливает значительные различия в характеристиках солнечной радиации для разных регионов России. Соответственно, существенно могут различаться и параметры следящих систем, обеспечивающих максимальную производительность солнечной электростанции. Опыт практического применения солнечных трекеров в России небольшой, и актуальной является задача выбора параметров следящей системы, обеспечивающих максимальную технико-экономическую эффективность фотоэлектрической станции в заданном районе ее эксплуатации. Цель исследования: выбор параметров и оценка эффективности применения солнечных систем слежения в высоких северных широтах Методы исследования: математическое и компьютерное моделирование с использованием программной среды MatLab/Simulink. Результаты. Рассмотрена классификация и основные компоненты солнечных следящих систем, выполнен анализ их основных технических характеристик. Даны рекомендации по выбору параметров следящих систем для эксплуатации в высоких северных широтах. Разработана имитационная модель фотоэлектрической станции с системой слежения за положением Солнца, обеспечивающая моделирование ее энергетических характеристик с учетом реальных условий эксплуатации. Рассмотрен практический пример выбора параметров и оценки эффективности применения солнечных систем слежения для фотоэлектрической станции, территориально расположенной в г. Томске.

Effect of spatial resolution of heliostat surface characterization on its concentrated heat flux distribution

The optical characteristics of solar concentrators are key factors influencing the overall efficiency of solar power plants. For instance, heliostats need to be evaluated prior to installation and during its operation lifetime. This guarantees that the optical and thermal performance of these systems is close to design. One methodology that has gained importance due to its potential capabilities has been the Fringe Reflection Technique. This technique uses the reflection of a series of regular stripes to obtain the local slope deviations from a specular surface. Coupled to a ray tracing analysis, these slopes can be used to identify the distortion in concentrated solar spots. The enormous amount of data needed to carry out this analysis difficult its implementation at large scale. In this work, a study for determining the optimal number of sample points for heliostat surface characterization is realized. It has been found that, depending on the level of errors, the number SPFS required to reach convergence in the flux distribution profiles and intercept factors is variable. However, for the wide range of parameters considered in all cases 48 SPFS where enough to reach convergences to 1%. This is equivalent to one point per every 2.5 cm of facet side length. For values of slope and canting errors up to 2 mrad, half this density is sufficient.

Assessing Solar Power Plant Efficiency Degradation Resulting from Heating

Assessing Solar Power Plant Efficiency Degradation Resulting from Heating

Towards the intrahour forecasting of direct normal irradiance using sky-imaging data

Increasing power plant efficiency through improved operation is key in the development of Concentrating Solar Power (CSP) technologies. To this end, one of the most challenging topics remains accurately forecasting the solar resource at a short-term horizon. Indeed, in CSP plants, production is directly impacted by both the availability and variability of the solar resource and, more specifically, by Direct Normal Irradiance (DNI). The present paper deals with a new approach to the intrahour forecasting (the forecast horizon Δtf is up to 30min ahead) of DNI, taking advantage of the fact that this quantity can be split into two terms, i.e. clear-sky DNI and the clear sky index. Clear-sky DNI is forecasted from DNI measurements, using an empirical model (Ineichen and Perez, 2002) combined with a persistence of atmospheric turbidity. Moreover, in the framework of the CSPIMP (Concentrating Solar Power plant efficiency IMProvement) research project, PROMES-CNRS has developed a sky imager able to provide High Dynamic Range (HDR) images. So, regarding the clear-sky index, it is forecasted from sky-imaging data, using an Adaptive Network-based Fuzzy Inference System (ANFIS). A hybrid algorithm that takes inspiration from the classification algorithm proposed by Ghonima et al. (2012) when clear-sky anisotropy is known and from the hybrid thresholding algorithm proposed by Li et al. (2011) in the opposite case has been developed to the detection of clouds. Performance is evaluated via a comparative study in which persistence models – either a persistence of DNI or a persistence of the clear-sky index – are included. Preliminary results highlight that the proposed approach has the potential to outperform these models (both persistence models achieve similar performance) in terms of forecasting accuracy: over the test data used, RMSE (the Root Mean Square Error) is reduced of about 20Wm−2, with Δtf=15min, and 40Wm−2, with Δtf=30min.

Thermodynamic Optimization of Supercritical CO2 Brayton Power Cycles Coupled to Line-Focusing Solar Fields

An opportunity for increasing the parabolic solar power plant efficiency is substituting the actual subcritical Rankine power cycles with the innovative s-CO2 Brayton cycles. In this paper, three configurations are assessed: the recompression cycle (RC), the partial cooling with recompression cycle (PCRC), and the recompression with main compression intercooling cycle (RCMCI), with one reheating stage. The thermodynamic parameters are optimized with three algorithms: SUBPLEX, UOBYQA, and NEWUOA, and the results validated with thermoflow Software. The parabolic troughs and linear Fresnel solar collectors are studied with different heat transfer fluids (HTFs): Solar Salt, HITEC XL, Therminol-VP1, Syltherm 800, and Therminol 75. The dual-loop solar field (SF), combining thermal oil and molten salt (MS) in the same solar plant, is also analyzed. The plant power output and plant energy efficiency are translated into SF aperture area and cost at design point. From the point of view of the plant efficiency and SF cost, the PTC and LF solar collector with Solar Salt as HTF coupled to a s-CO2 Brayton RCMCI cycle is selected as the optimum design solution and compared with the actual PTC Rankine solar plant performance at design point. The total recuperator conductance (UA) plays an important role in optimizing the plant performance, limited by the minimum heat exchangers (HX) pinch point. The UA increment could compensate the HX pressure drop and the compressor inlet temperature (CIT) increment, both impacting very negatively in the s-CO2 plant performance.

Influence of receiver surface spectral selectivity on the solar-to-electric efficiency of a solar tower power plant

The spectral selectivity results in increasing the absorption of the incident solar flux and decreasing the radiative losses due to emission of heated walls. This study investigates the influence of the spectral selectivity on power generation efficiency of a central receiver solar concentrating system (solar power tower). A parametric study is conducted to quantify the potential efficiency gain that may result from spectral selectivity with the solar absorption, the cutoff wavelength, the infrared emissivity, the wall temperature and the receiver geometry (plane or cavity) as parameters. The model used to compute the receiver efficiency is based on a Monte Carlo ray-tracing algorithm for the radiative losses, the Clausing model for the convective losses and the Chambadal–Novikov–Curzon–Ahlborn approach for thermodynamic efficiency. The two tested receiver geometries are a plane receiver and a cubic cavity having the same cross section area of the aperture. State-of-the-art (metal alloys) and promising ceramic materials were studied such as SiC, ZrB2, ZrC and TaC. In the latter cases the native measured optical properties of carbides are considered. Finally, an intrinsic spectrally selective material such as TaC demonstrates promising results with global facility efficiency close to the maximum when solar absorptivity is enhanced by microstructuration, for example. As a conclusion, it is shown that spectral selectivity may result in an increase of overall solar power plant efficiency by about 6% (or 28% in relative value) with current state-of-the-art.

An Analysis of the Effect of Molten Salt Thermal Storage on Parabolic Trough Concentrated Solar Power Plant Efficiency

In the development of renewable energy sources, there has been a trend toward increasing and stabilising the power output of Concentrated Solar Power Plants (CSPPs) during times of reduced solar resource through the use of Thermal Energy Storage Devices (TESDs). This study investigates whether the use of a molten salt TESD decreases the efficiency of a parabolic trough CSPP due to additional system energy losses despite prolonging the operational time of the CSPP. A theoretical analysis of a simplified CSPP was made to determine if a TESD would impact the efficiency of the CSPP. This was followed up by a survey of currently active parabolic trough CSPPs both with and without molten salt TESDs. The theoretical analysis illustrated that a TESD would have no effect on the efficiency of a CSPP. However, the survey revealed that the use of a TESD improved the efficiency of a CSPP. The results of the study don't support the theoretical analysis or the hypothesis suggesting that a property has been overlooked. This property is most likely to be that generators tend to operate best within a certain temperature range, and in a CSPP the optimum temperature range cannot be maintained. This results in a generator being selected capable of operating for the longest period with the lowest amount of excess solar energy. When a TESD is implemented, the excess solar energy is stored for later use, prolonging the generator's running time and increasing the useable energy. The realisation of the ability of a TESD to increase the efficiency of a CSPP as well as extending its operating time shows a promising area of development in CSPP technology and increasing its application in electricity generation.