Computer simulation of the influence of shading on a solar photovoltaic array

ABSTRACT

Partial shading has been identified as a major simulation programme. The PVSYST simulation software has been used to evaluate the behaviour of, or cause for, reducing the energy of photovoltaic systems. In the present work the influence of shading effects on a solar photovoltaic array has been analysed, emphasising different shading quantities and changing the string length with the computer system for different shading situations. The result shows that the maximum power point of shaded string is not greatly influenced by the quantity of shade on one cell of that string ranging from 793?W at 25% shading to 780?W at 99% shading. The power generated at the maximum power point is reduced from 1846?W to 1530?W, that is, 17.1% reduction, which is a larger loss than the system comprising 4 modules in series and two strings in parallel with a loss of 9.1%.     

Advanced sliding mode control for solar PV array with fast voltage tracking for MPP algorithm

ABSTRACT

This paper presents a photovoltaic (PV) system with a maximum power point tracking (MPPT) method. The main aim of this work is to collect the maximum power generated from a solar photovoltaic generator (PVG). This goal is accomplished by integrating a sliding mode controller (SMC) that drives a voltage source inverter (VSI) connected between the PVG and the load. The system is modelled and tested in MATLAB/SIMULINK. In simulation, the SMC gives a fast and accurate convergence to the MPP that is tracked by incremental conductance (INC) type MPPT algorithm. The consequence of the system is capable of tracking MPPs accurately and rapidly without steady-state oscillation and also its performance is satisfactory. The INC type MPPT algorithm is used to track MPPs because it exhibits a precise control under rapidly changing atmospheric conditions. As the solar energy gives the variable light energy at different times and is not constant, the SMC performance is calculated at variable irradiation points by using one slider gain for the variation of the insolation levels.     

Potential of renewable energy system utilisation at decentralised level in the state of Uttarakhand in India

ABSTRACT

Design and implementation of an effective dissemination programme for decentralised renewable energy system necessitate an accurate estimate of its utilisation potential. Hence, in this study, an attempt has been made to develop frameworks to estimate the utilisation potential of decentralised renewable energy systems in the state of Uttarakhand in India. Estimations imply large resource, technical and economic potentials of the domestic solar water heater, solar home system, solar lantern, family size biogas plant and improved biomass cookstove in Uttarakhand. With higher impact on the purchasing power of households, prevailing soft loan scheme has been found to be more appropriate than a capital subsidy for promoting the usage of decentralised renewable energy systems.     

太阳能光伏发电系统的技术发展

太阳能PV系统从军用到民用、从离网系统到并网系统已经走过了半个多世纪的历程,效率不断提高,技术日益完善,发电成本逐年下降。随着科技的发展,大规模利用PV技术进行太阳能发电已经蓬勃兴起,而大量分散型PV电源的入网又需要发展微网系统、智能电网系统和全球PV供电系统。     

A heat pipe photovoltaic/thermal (PV/T) hybrid system and its performance evaluation

Building-integrated photovoltaic/thermal (BIPV/T) system has been considered as an attractive technology for building integration. The main part of a BIPV/T system is PV/T collector. In order to solve the non-uniform cooling of solar PV cells and control the operating temperature of solar PV cells conveniently, a heat pipe photovoltaic/thermal (PV/T) hybrid system (collector) has been proposed and described by selecting a wick heat pipe to absorb isothermally the excessive heat from solar PV cells. A theoretical model in terms of heat transfer process analysis in PV module panel and introducing the effectiveness-number of transfer unit (?-NTU) method in heat exchanger design was developed to predict the overall thermal-electrical conversion performances of the heat pipe PV/T system. A detailed parametric investigation by varying relevant parameters, i.e., inlet water temperature, water mass flow rate, packing factor of solar cell and heat loss coefficient has been carried out on the basis of the first and second laws of thermodynamics. Results show that the overall thermal, electrical and exergy efficiencies of the heat pipe PV/T hybrid system corresponding to 63.65%, 8.45% and 10.26%, respectively can be achieved under the operating conditions presented in this paper. The varying range of operating temperature for solar cell on the absorber plate is less than 2.5 °C. The heat pipe PV/T hybrid system is viable and exhibits the potential and competitiveness over the other conventional BIPV/T systems.     

Modelling and simulation of single- and triple-junction solar cells using MATLAB/SIMULINK

The main objective of this paper is to determine the single- and triple-junction solar cells’ I–V and P–V curves, define maximum voltage, current, and power. The paper demonstrates and analyses different environmental conditions that affect the solar cells, such as temperature and irradiance. The performance of single- and triple-junction solar cells is evaluated by analysing the fill factor. In this work, the analysis of single- and triple-junction solar cells is carried out through software simulation. Different conditions demonstrated to observe the results of this variation in both single- and triple-junction cells, such as observing the solar cell behaviour under variation of temperature between 15°C (288.315?K) and 45°C (318.15?K) for the single-junction cell and between 268.15?K (?5°C) and 348.15?K (75°C) for the triple-junction cell to observe the effect of temperature on open circuit voltage, the variation of different levels of irradiance to observe its effect on open circuit voltage and current density on both cell types, and cell performance evaluation using the fill factor concept. Practical results used in this paper are obtained from Clyde Space’s laboratories. Tests of Clyde Space were done using halide lamps to simulate the irradiation conditions with irradiance of half sun which is equivalent to 0.05?W?cm^?2. The operation was done under temperature of 40°C which is equivalent to 313.15?K.     

Controlling power output of solar chimney power plant according to demand

ABSTRACT

The solar chimney power plant (SCPP) is a simple solar thermal power plant that is capable of converting solar energy into thermal energy in the solar collector. In the second stage, the generated thermal energy is converted into kinetic energy in the chimney and ultimately into electric energy using a combination of a wind turbine and a generator. The numerical simulations were performed for the geometry of the prototype in Manzanares, Spain. Using computational ?uid dynamics (CFD) techniques; we have simulated a two-dimensional axisymmetric model of a SCPP with the RNG k-ε turbulence. In this model, the discrete ordinates (DO) radiation model was implemented to solve the radiative transfer equation, using a two-band radiation model. The main objective of this work is to explore dynamic control over plant power output. We have presented a technique to control the power output of the solar chimney power plant, in order to deliver power according to specified demand patterns. In order to present this, the reference plant model was modified to include a secondary and tertiary collector roof under the existing main collector. In terms of base load electricity generation, the inclusion of a secondary and tertiary collector roof produces good control over plant output.     

Solar space power: an overview

ABSTRACT

Degradation of environment due to toxic emissions and global warming has motivated scientists to look for alternative green energy resources such as space solar power. Terrestrial solar power (TSP) is not reliable as it is limited by weather condition and seasonal sunlight illumination variations while Space Solar Power (SSP) has the advantages of high energy density and efficiency as well as continuity and stability. This paper presents the concepts of space-based solar power, along with the various technologies and recent research involved in this field.A comparison of SSP and TSP is also presented based on various parameters. This technology would prove to be a very promising energy source for sustainable development in the near future.     

A nodal thermal model for photovoltaic systems: Impact on building temperature fields and elements of validation for tropical and humid climatic conditions

This article deals with both an experimental study and a numerical model of the thermal behaviour of a building whose roof is equipped with photovoltaic panels (PV panels). The aim of this study is to show the impact of the PV panels in terms of level of insulation or solar protection for the building. Contrary to existing models, the one presented here will allow us to determine both the temperature field of the building and the electric production of the PV array. Moreover, an experimental study has been conducted in La Reunion Island, where the climate is tropical and humid, with a strong solar radiation. In such conditions, it is important to minimise the thermal load through the roof of the building. The thermal model is integrated in a building simulation code and is able to predict the thermal impact of PV panels installed on buildings in several configurations and also their production of electricity. Basically, the PV panel is considered as a complex wall within which coupled heat transfer occurs. Conduction, convection and radiation heat transfer equations are solved simultaneously to simulate the global thermal behaviour of the building envelope including the PV panels; this is an approach we call ‘integrated modelling’ of PV panels. The experimental study is used to give elements of validation for the numerical model and a sensitivity analysis has been run to put in evidence the governing parameters. It has been shown that the radiative properties of the PV panel have a great impact on the temperature field of the tested building and the determination of these parameters has to be taken with care.     

Techno-economic analysis of 1 MWp grid connected solar PV plant in Malaysia

Most of the public and private technical universities in Malaysia have considerably abundant free areas, which could be a better place for equipping the renewable energy harvesters. The main objective of this paper is to analyse the feasibility of developing a solar PV plant at two different campuses of Universiti Malaysia Pahang (UMP). This paper proposes 1 MW solar PV power plant at the Pekan Campus (Rural Campus), and Gambang (Suburban Campus) of UMP located in the east coast state of Pahang, which is biggest among other states in Peninsular Malaysia. The technical viability of the proposed crystalline technology based PV plant with open rack or free stand mounting position is analysed using PVGIS (Photovoltaic Geographical Information Systems) and PV Watts’s software. The economic and environmental aspects of the proposed plant are also analysed based on standard parameters. The proposed plant of 1?MWp Solar PV plant can generate around 1390?MWh, of electricity per annum with a GHG emission reduction of 818.71 tCO₂ per annum. The PV power plant can contribute in meeting 5% of total energy requirements of the campus. The technical performance obtained through PVGIS is quite comparable with the PV Watts results.     

Modeling and analysis of solar photovoltaic-electrolyzer-fuel cell hybrid power system integrated with a floriculture greenhouse

This paper presents the modeling and analysis of a greenhouse-integrated power system consisting of solar photovoltaic panels, electrolyzer bank and Polymer Electrolyte Membrane (PEM) fuel cell stacks. Electric power is generated in an array of solar photovoltaic modules. Excess energy after meeting the requirements of the greenhouse during peak sunshine hours, is supplied to an electrolyzer bank to generate hydrogen gas, which is consumed by the PEM fuel cell stack to support the power requirement during the energy deficit hours. The predicted performance of the integrated system is presented for different climatic conditions, for a given location (Kolkata) in the Indian subcontinent. The study reveals that 51 solar photovoltaic modules each of 75W_p along with a 3.3 kW electrolyzer and 2 PEM fuel cell stacks, each of 480 W, can support the energy requirement of a 90 m² floriculture greenhouse with fan-pad ventilated system. The study shows that this integrated power system provides a viable option for powering stand-alone greenhouses in a self-sustained manner.     

TDK甲府工厂300kW太阳能光伏发电系统工程案例介绍

日本的太阳能光伏产业在国际上一直处于领先地位,本文通过介绍日本TDK甲府工厂项目,让业界了解日本公共产业用太阳能光伏发电系统的设置成本、发电量、经济收益、社会影响等。日本TDK甲府工厂300kW太阳能光伏发电系统作为与日本NEDO的合作项目,在经济和社会影响等方面都产生了较好的效果。     

Reactive power pricing in power markets: a comprehensive review

ABSTRACT

Reactive power is one of the main characteristics that play a major role in power systems. When reactive flow is inadequate, the power system is confronted with voltage collapse and more than enough reactive power production follows the circulation in the network and consequently the occupation of power lines. On the other hand, power market evolves from centralised and vertically integrated structure to a competitive environment. The reactive power market is different from energy market and like others such as spinning reserve, frequency control and power system stabiliser is taken in the category of the ancillary service market. This paper reviews various mechanisms for pricing of reactive power in both levels of transmission and distribution (T&D) system. Additionally, the cost paid for reactive power service in the presence of distributed energy resources is analysed because of their high penetration in the power system, especially in distribution level.     

A novel fault ride-through technique for grid-connected Photo Voltaic energy systems

In this article, a novel fault ride-through technique has been implanted with a double control loop method. This method is implemented with voltage-source converters, where the active and reactive power could be easily done with the voltage control loop and inherent current control loop. The proposed system has been implemented to grid-connected photovoltaic systems, and the results have been explored and compared with the existing techniques. An additional control strategy is implemented successfully for satisfactory performance of the system during low irradiance periods, and the system is made capable to provide Q-support to the grid according to the system operators request with the help of Q-set point.     

Optimal sizing of building integrated hybrid PV/diesel generator system for zero load rejection for Malaysia

In this research, an optimisation for building integrated hybrid PV/diesel generator system for zero load rejection for Malaysia is performed. The optimisation is performed considering a loss-of-load probability (LLP) less than 0.01. However, the daily averages of solar energy for Malaysia and a mathematical model of a hybrid PV/diesel generator system are used in this optimisation. The optimisation presented in this paper aims to calculate the optimum capacities of a PV array and diesel generator, which investigate the minimum system cost. An optimisation problem in terms of system units’ cost is solved graphically in this study. Moreover, the optimised system is compared to other energy source choices to highlight its feasibility. The recommended configuration of a PV/diesel system located in Malaysia is C_A = 1.2, C_DG = 0.3, while the optimum C_B is 0.1. The results of the optimisation show that a PV/diesel generator choice is more feasible compared to a standalone PV system or diesel generator system because it reduces the system cost by 35%.     

Comments on “Analytical expression for electrical efficiency of PV/T hybrid air collector” by S. Dubey,G.S. Sandhu,and G.N. Tiwari

In this short communication, a theoretical attempt has been made and the analytical expression developed by Dubey, Sandhu, and Tiwari [2009. “Analytical Expression for Electrical Efficiency of PV/T Hybrid air Collector.” Applied Energy 86: 697–705.] for temperature-dependent electrical efficiency of air type PV/T collector has been corrected. The analyses have indicated that their efficiency expression only considers the effects of solar intensity. However, it is unequivocal from the governing equations that the ambient temperature is another variable that should be in the efficiency expression as an initial condition of the energy balance equation of flowing air. Although they asserted that the electrical efficiency of the system has been evaluated with respect to the variations in solar intensity and ambient temperature for a typical day in the month of April 2008 for New Delhi condition, the results clearly show that the ambient temperature has not been taken into account in their study. Their expression not including a term for ambient temperature proves our statement. In the present work, the corrected version of the efficiency expression is given.     

Solar energy performance analysis of basin-type solar still under the effect of vacuum pressure

ABSTRACT

This paper deals with a solar still for distilled water, using the heat of the sun to evaporate, cool and then collect the water. They are used in areas where drinking water is unavailable, so that clean water is obtained from dirty water or from plants by exposing them to sunlight; vacuum pressure is delivered to still-type solar. The reason for selecting vacuum pressure is that during the monsoon and cloudy days, solar intensity will not be high as it leads to evaporation at lower temperature saline water under the soar still. The basin area for the production of 5 litres per day of fresh water is determined as 1.44?m²and the solar still basin area of 1.44?m² and 21.5° tilt angle are designed. Solar energy be may used full to alternate in electrical power and to purify water in future. Finally, the performance was analysed for the solar still with a vacuum pressure at 0.6 bar. The outcome of the theoretical analysis shows that adoption of 0.6 bar pressure inside the solar still improves the average performance by 30%. In order to overcome this problem, vacuum could be applied for the better performance of the solar still during the low solar intensity periods.     

道路照明领域中太阳能供电应用

在道路照明领域中,太阳能供电是一种新颖绿色环保的节能措施。本文在分析确定路灯光源的基础上,通过对市电和蓄电池电互相切换来选用稳定可靠地控制系统及此配电方式所适用地区。     

Optimum configuration and design of a photovoltaic–diesel–battery hybrid energy system for a facility in University of Port Harcourt,Nigeria

Optimum configuration, using a hybrid optimisation model for electric renewable software, and design of a photovoltaic (PV)–diesel–battery hybrid energy system has been proposed to power a facility in the University of Port Harcourt, which is located in the suburb of Port Harcourt city, Nigeria. The configuration of the optimum hybrid system is selected based on top-ranked system configuration, according to the net present cost. An optimal system design delivers the best components alongside appropriate operating strategies to provide the most efficient, reliable cost-effective system possible. The system investigated reduces CO₂ emissions by 36.3%/year. This will reduce costs imposed on CO₂ emissions by future environmental legislation. The system has a better potential for providing the energy needs of the facility considered in this paper compared with a stand-alone PV–battery system as capital costs are reduced by 55%. Reliability was improved as the diesel generator can provide power as and when it is needed.     

Potential for a Danish power system using wind energy generators,solar cells and storage

Some overall properties of a power system in a northern climate based mainly upon renewable energy are studied.

The power system consists of wind energy generators and solar cells in combination with a storage system and a back-up system. The type of power plants constituting the back-up system are not specified. The back-up system could be used to generate power only when the rest of the system is unable to cover the load. The predicted performance of the solar/wind power system is calculated on the basis of hourly meteorological data measured in Denmark during the years 1959 to 1972.

It has been established from this data that to maximise the fraction of annual load covered by solar and wind energy the ratio of solar to wind production capacity is approximately 40% solar to 60% wind. With only small changes in the energy provision, however, the ratio could be varied between 20:80 and 60:40.

The saving in energy resulting from provision of various storage capacities has been studied. This saving will be negligible if less than half of the annual load is covered by the solar/wind power system. For a solar/wind power system with a production capacity of 1.25 times the annual load the marginal energy saving effect of a storage system is reduced by a factor of 10 when the storage capacity is increased from 0 to 24 hours. The marginal costs of producing the electricity rise steeply when more than about 80–90% of the load is to be covered on the basis of renewable energy. Finally it is shown that when 80% of the load is covered by renewable energy the storage capacity should not exceed 40 hours.