Photovoltaic Solar Collectors Research Articles

CFD Prediction of dust deposition and installation parametric optimisation for soiling mitigation in non-tracking solar PV modules

ABSTRACT The influence of installation parameters on dust accumulation behaviour for ground mounted solar photovoltaic collectors were investigated by computational fluid dynamics simulation. The effect of wind direction relative to the direction of the incident solar radiation on the photovoltaic module was also studied. The shear stress transport k − ω turbulence model and the discrete phase model were respectively adopted for wind flow simulation and dust deposition prediction. Installation parameter optimisation for minimum soiling and maximum energy generation was carried out using response surface methodology. Tilt angle was found to have a greater effect on dust deposition compared to orientation. A predictive model was developed for dust deposition and had a coefficient of determination, mean absolute percentage error and residual mean square error values of 0.983, 5.4 particles and 1.29 MWh/year respectively. The optimal installation configuration for a selected location was determined and it was found to produce 3.5% more energy than a system installed using tilt as the latitude angle and facing north in the same location. When wind flows from behind the solar photovoltaic module, there is 16% more energy generated than when wind flow is directly in front of the solar photovoltaic module at the optimal installation configuration.

Enhanced electrical performance in a solar photovoltaic module using V-trough concentrators

The electrical performance of a novel solar photovoltaic collector fabricated by lamination of silicon PV cells onto a copper metal sheet using EVA as the bond material and adding a single water channel underneath was further improved by using V-trough booster reflector mirrors. From the ray-tracing analysis, it was observed that under fixed tilt of 13°, the one-mirror arrangement even though of less concentration provides uniform illumination for seven months, whereas the two-mirror arrangement does not provide uniform illumination in any month except June. The non-uniform illumination on the solar photovoltaic collector due to different incidence angles throughout the day, can be minimized by increasing the length of the reflector mirrors by 2.82 times the length of the modified PV module. Experimental results show that due to the fixed tilt of the V-trough concentrator and the reflection losses on the glazing, the increase in electrical power was realized only for a duration of 90–120 min around solar noon in one-mirror arrangement and for about 60 min around solar noon in the two-mirror arrangement. The higher power output observed for the fixed tilt V-trough concentrator during peak noon conditions is favourable for peak noon demand such as air-conditioning, irrigation, etc.

Exergoeconomic analysis and optimization of a solar based multigeneration system using multiobjective differential evolution algorithm

This paper presents and analyzes a multigeneration energy system that consists of a reverse osmosis desalination unit, water heater, organic Rankine cycle, photovoltaic solar collectors, and a single effect absorption chiller. In doing so, energy and exergy analysis are first performed to evaluate the performance of the system and determine the irreversibility of each component. Next, considering minimizing total cost rate and maximizing exergy efficiency as two objective functions, a multiobjective optimization approach based on differential evolution algorithm is proposed to determine the best design parameters. A self-adaptive technique is utilized to deal with the search capability, population diversity, and convergence speed of the proposed optimization algorithm. An external archive list is used to save all nondominated optimal solutions during the optimization. Dynamic crowding distance approach is employed to decrease archiving size without losing its characteristics. Furthermore, a fuzzy clustering approach is used to select the desired solution among the Pareto-optimal solutions. Simulation results are compared with two other multiobjective optimization algorithms and effectiveness of the proposed optimization method is verified using various indices. Finally, a sensitivity analysis is employed to evaluate effects of design parameters on exergy efficiency and total cost rate of the system.

An Energy Autonomous House Equipped with a Solar PV Hydrogen Conversion System

The use of RES in buildings is difficult for their random nature; therefore the plants using photovoltaic solar collectors must be connected to a power supply or interconnected with Energy accumulators if the building is isolated. The conversion of electricity into hydrogen technology is best suited to solve the problem and allows you to transfer the solar energy captured from day to night, from summer to winter. This paper presents the feasibility study for a house powered by PV cogeneration solar collectors that reverse the electricity on the control unit that you command by a PC to power the household, using a heat pump, an electrolytic cell for the production of hydrogen to accumulate; control units sorting to the utilities the electricity produced by the fuel cell. The following are presented: The Energy analysis of the building, the plant design, economic analysis.

Performance Evaluation of Hybrid Photovoltaic and Thermal Solar Collector in Jordan

ABSTRACTJordan has excellent potential for solar energy with 2080 kWh/m2 global radiation and more than 300 sunny days a year. An integrated Hybrid Photovoltaic-Thermal (PV/T) solar collector system was constructed and operated at Mutah University in Jordan. The performance of the integrated Hybrid Photovoltaic-solar collector system was evaluated analytically and experimentally. The total sun insolation and various inlet, outlet and tank temperatures were recorded instantaneously every hour of the day for several months in 2010. The discretized temperature distribution of the integrated system and the stratification of the tank were solved numerically. The integrated system was discretized using forward finite difference. The Runge-Kutta fourth order method was used to solve the discretized nodes. Computational Fluid Dynamics (CFD) calculations were used to predict and to evaluate the inlet velocity, temperature, operating pressure of the integrated Hybrid PV/T solar collector system. Good agreement was ...

Design and Dynamic Simulation of a Combined System Integration Concentrating Photovoltaic/Thermal Solar Collectors and Organic Rankine Cycle

This study presents the design of a novel ultra-high efficient solar power system. The system is equipped with a concentrating PhotoVoltaic/Thermal (CPVT) solar collectors bottomed by an Organic Rankine Cycle (ORC). The basic idea is to use a high temperature CPVT device producing simultaneously electricity and hot diathermic oil. Then, this hot fluid is used to supply heat to the Organic Rankine Cycle producing additional electricity. The collector is based on a combination of a parabolic dish concentrating solar thermal collector and a high efficiency solar photovoltaic collector. Among the possible high-temperature PVT systems, this paper is focused on a system consisting in a dish concentrator and in a triple-junction PV layer. In particular, the prototype consists in a parabolic dish concentrator and a planar receiver. The system is equipped with a double axis tracking system. The bottom surface of the receiver is equipped with triple-junction silicon cells whereas the top surface is insulated. Similarly, the ORC subsystem is equipped with tube and shell heat exchangers, a pump and an expander. In order to analyze the performance of the CPVT collector and ORC cycle, detailed mathematical models were implemented. These models are based on zero-dimensional energy balances on the control volumes of the system. The simulation model allows one to calculate in detail the temperatures of the main components of the system and the main energy flows. Both CPVT and ORC models are integrated in a more complex dynamic simulation model, developed in TRNSYS environment. Here, additional components are included in the system: Pump, tank, controllers, valves, etc. The input parameters of the model include weather conditions (temperature, insolation, wind velocity, etc.) and the geometrical/material parameters of the systems. This novel system was compared with a more conventional one, consisting of a concentrating PV collector equipped with III-V cells. Results showed that such second system (only CPVT) is more profitable from an economical point of view, with a 20 years Net Present Value 15% higher than the novel system (CPVT+ORC). Conversely, the novel (ORC+CPVT) system produces 6% more electrical energy.

A novel solar trigeneration system based on concentrating photovoltaic/thermal collectors. Part 1: Design and simulation model

This paper analyzes the thermodynamic performance of high-temperature PhotoVoltaic/Thermal (PVT) solar collectors. The collector is based on a combination of a parabolic dish concentrating solar thermal collector and a high efficiency solar photovoltaic collector. The PVT system under investigation allows one to produce simultaneously electrical energy and high-temperature thermal energy by solar irradiation. The main aim of this study is the design and the analysis of a concentrating PVT which is able to operate at reasonable electric and thermal efficiency up to 180 °C. In fact, the PVT is designed to be integrated in a Solar Heating and Cooling system and it must drive a two-effect absorption chiller. This capability is quite new since conventional PVT collectors usually operate below 45 °C. Among the possible high-temperature PVT systems, this paper is focused on a system consisting in a dish concentrator and in a triple-junction PV layer. In particular, the prototype consists in a parabolic dish concentrator and a planar receiver. The system is equipped with a double axis tracking system. The bottom surface of the receiver is equipped with triple-junction silicon cells whereas the top surface is insulated. In order to analyze the performance of the Concentrating PVT (CPVT) collector a detailed mathematical model was implemented. This model is based on zero-dimensional energy balances on the control volumes of the system. The simulation model allows one to calculate in detail the temperatures of the main components of the system (PV layer, concentrator, fluid inlet and outlet and metallic substrate) and the main energy flows (electrical energy, useful thermal energy, radiative losses, convective losses). The input parameters of the model include all the weather conditions (temperature, insolation, wind velocity, etc.) and the geometrical/material parameters of the systems (lengths, thermal resistances, thicknesses, etc.). Results showed that both electrical and thermal efficiencies are very good in a wide range of operating conditions. The study also includes a comprehensive sensitivity analysis in which the main design variables were varied in order to evaluate the related variations of both electrical and thermal efficiencies.

Hybrid solar collector

The paper presents a hybrid solar collector converting the solar energy into both thermal and electric ones. Thus, the solar energy losses are captured to obtain co-generation. The research was conducted at the “Renewable Energy Sources” Laboratory at the Technical University – Sofia, established under the European Tempus Program. The authors present a structure and an approach to study this combined collector, which consist in determining the coefficients of the heat exchange by way of consecutive approximations. The thermal characteristics of the collector, and especially the fluid temperature, the absorber temperature and the cover temperature are determined. The thermal, electrical and total efficiency of the system are also obtained. The results indicate that it is possible to obtain more energy per unit of surface compared to the thermal and the photovoltaic solar collectors separately.

Wind tunnel experiments and field investigations of eolian dust deposition on photovoltaic solar collectors

Wind tunnel simulations and field experiments were executed to investigate the deposition of atmospheric dust on solar collectors. In the wind tunnel, dust storms were simulated on scale models of a photovoltaic collector. The effect of wind velocity, wind direction, and diurnal collector rotation upon the total amount of dust settling on the collector is examined. Also investigated is the distribution of the dust over the three distinct panels (2 mirrors + 1 photovoltaic panel) of the collector. Wind direction and solar collector rotation appear to have a serious impact on dust deposition and dust deposition distribution. Wind velocity, on the other hand, has only a small effect on dust deposition distribution, provided wind speed is sufficiently high (some m · s −1 at minimum). Field experiments were executed on real-size collectors to verify the wind tunnel data. The wind tunnel results approximate the field results very closely. This demonstrates the usefulness and importance of the technique in solar collector research.

Grounding of space structures

Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the ‘blanket’ of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as ‘grounding’, or false stiffening, of the stiffness matrix occurs during rigid body rotation. This paper examines the grounding phenomenon in detail. Numerous stiffness matrices developed by others are examined for rigid body rotation capability, and found lacking. A force imbalance inherent in the formulations examined is the likely cause of the grounding problem, suggesting the need for a directed force formulation.

A new pre-loaded beam geometric stiffness matrix with full rigid body capabilities

Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the ‘blanket’ of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as ‘grounding’, or false stiffening, of the stiffness matrix occurs during rigid body rotation. The authors have previously shown that the grounding phenomenon is caused by a lack of rigid body rotational capability, and is typical in beam geometric stiffness matrices formulated by others, including those which contain higher order effects. The cause of the problem was identified as the force imbalance inherent in the formulations. In this paper, the authors develop a beam geometric stiffness matrix for a directed force problem, and show that the resultant global stiffness matrix contains complete rigid body mode capabilities, and performs very well in the diagonalization methodology customarily used in dynamic analysis.

Dynamic analysis of space-related linear and non-linear structures

In order to be cost-effective, space structures must be extremely light-weight, and subsequently, very flexible structures. The power system for Space Station ‘Freedom’ is such a structure. Each array consists of a deployable truss mast and a split ‘blanket’ of photo-voltaic solar collectors. The solar arrays are deployed in orbit, and the blanket is stretched into position as the mast is extended. Geometric stiffness due to the preload make this an interesting non-linear problem. The space station will be subjected to various dynamic loads, during shuttle docking, solar tracking, attitude adjustment, etc. Accurate prediction of the natural frequencies and mode shapes of the space station components, including the solar arrays, is critical for determining the structural adequacy of the components, and for designing a dynamic controls system. This paper chronicles the process used in developing and verifying the finite element dynamic model of the photo-voltaic arrays. Various problems were identified in the investigation, such as grounding effects due to geometric stiffness, large displacement effects, and pseudo-stiffness (grounding) due to lack of required rigid body modes. Various analysis techniques, such as development of rigorous solutions using continuum mechanics, finite element solution sequence altering, equivalent systems using a curvature basis, Craig-Bampton superelement approach, and modal ordering schemes were utilized. This paper emphasizes the grounding problems associated with the geometric stiffness.

A thermo-electric refrigerator powered by photo-voltaic solar collectors

In developing countries and remote areas where an electric supply is not available, a thermo-electric refrigerator is often needed for food and medical drugs storage. Such a refrigerator, which requires a direct current supply is suitable for matching with a photo-voltaic collector (PV). A normal automobile 12-volt lead-acid battery may be used as the storage system. This refrigerator is rugged and may be operated by unskilled people: a prototype has been built and its components are available commercially.