The potential and economic viability of solar photovoltaic power in Ghana

In this study, the potentiality and economic viability of solar photovoltaic (PV) in Ghana was assessed using RETScreen software. 5 MW of grid-connected solar PV power system using SunPower SPR-320E-WHT-D PV module can be harnessed from Navrongo, Bawku, Wa, Tema, Bolgatanga, Axim, Salaga, Kintampo, Kete Krachi, Tamale, Hohoe, Koforidua, Ejura, Takoradi, Bole, Sunyani, Bibiani, Cape coast, Prestea, and Akuse, which requires US$17,752,179 of investment capital and 25,313 m² of land for PV installation. The potential of 5 MW grid-connected PV development for Accra, Kumasi, Wenchi, and Tafo are limited. However, there are solar PV energy potentials for low-capacity PV modules for these locations. Investing in solar photovoltaic technology is capital intensive in a developing country like Ghana. However, Government’s effort to provide incentives like subsidies and creating the economic environment for private sector investment will boost investment possibilities of renewable energy in Ghana, which can help in curbing the recent power outages and load shedding, thereby increasing productivity and economic resilience.     

某15MW太阳能屋顶光伏发电工程的应用分析

在对太阳能屋顶光伏发电系统构成及发展意义阐述的基础上,通过对某15MW屋顶光伏发电工程大量实际数据的分析,表明太阳能屋顶光伏发电工程具有良好的社会、经济效益和广阔的发展前景。     

空间站太阳能光伏和热动力电源系统的比较

针对我国未来空间站的建设，对目前可行的电源系统的技术特性做了分析比较。太阳光伏电池技术成熟，有应用经验，但其效率低，面积大，寿命不够理想，后期运行费用很高。太阳能热动力系统利用相变材料蓄热来满足阴影期循环的连续发电要求，具有效率高、结构紧凑、寿命长、质量轻、可靠性好等优点，长期运行的费用低，是一种先进的太阳能电源方案，其中闭式Baryton循环系统总效率可达到17％，在技术上比Stirling循环成熟，是最有可能近期实现的电源。闭式Brayton循环可以作为空间站太阳能电源系统的首选技术方案。     

Grid‐connected photovoltaic power plants: A review of the recent integration requirements in modern grid codes

The high integration of photovoltaic power plants (PVPPs) has started to affect the operation, stability, and security of utility grids. Thus, many countries have established new requirements for grid integration of solar photovoltaics to address the issues in stability and security of the power grid. In this paper, a comprehensive study of the recent international grid codes requirement concerning the penetration of PVPPs into electrical grids is provided. Firstly, the paper discusses the trends of PVPPs worldwide and the significance of improving grid codes' requirements. In addition, the comparison of common requirements covered in the majority of international grid codes considers high‐ and low‐voltage ride‐through capabilities, voltage and frequency regulation, and active and reactive power support requirements. Finally, a broad discussion on the compliance technology challenges and global harmonization of international grid codes that the PVPPs have to address is presented. The study summarizes the most recent international regulation regarding photovoltaic integration and research findings on the compliance of these regulations and proposed recommendations for future research. It also can assist power system operators to compare their existing requirements with other universal operators or establish their own regulations for the first time. Additionally, this research assists photovoltaic manufacturers and developers to get more accurate understanding from the recent global requirements enforced by the modern grid codes.     

Efficiency enhancement in large-area organic photovoltaic module using theoretical power loss model

For efficiency enhancement of a large-area monolithic organic photovoltaic (OPV) module, we studied the influence of the OPV cell geometry parameters using theoretical and experimental methods. For this work, a unit OPV cell as a reference device and four types of monolithic OPV module with different active cell lengths were fabricated together on a glass substrate. The characteristics of the fabricated unit OPV cell were measured and the voltage (V_mp) and current density (J_mp) at the maximum power point were extracted. The parasitic power losses were calculated from the extracted parameters and the material parameters using a theoretical power loss model, taking into consideration the series resistance, contact resistance, and shading (or dead area) losses at the calculated maximum power of the monolithic OPV module. To analyze the influence of OPV cell layout on efficiency of the large-area monolithic OPV module, the power conversion efficiency of the four type monolithic OPV modules with different active cell lengths was measured and compared with the calculated power conversion efficiency. The calculated PCE ratio of the monolithic OPV module with three cells was approximately 78%, and the measured PCE ratio of the fabricated monolithic OPV module with three cells was also approximately 78%. The measured PCE ratio of fabricated monolithic OPV modules with two, four, and five cells also exhibited this tendency for the calculated PCE ratio. Thus, a large-area monolithic OPV module with optimum electrical power loss and an appropriate number of OPV cells can be designed by extracting the parameters of the unit OPV cell and calculating the electrical power loss using the proposed theoretical power loss model.     

Development process of solar photovoltaic system cooling technology

光伏系统在运行时,冷却太阳能光伏电池板使其达到更高的效率是一个关键因素。适当的冷却可以提高电力效率,并随着时间的推移降低电池退化的速度,从而使光伏组件的寿命最大化。综述了传统冷却技术中自然循环对流冷却、强制对流循环冷却和液冷技术,新型冷却技术浮动跟踪集中冷却系统、混合PV/T系统冷却、混合PV/TE系统采用散热器冷却以及通过使用相变材料来提高太阳能光伏电池板的性能。根据研究的重点、贡献和实际应用分析各技术的优缺点、适合应用的领域及各自技术的经济特点。未来的技术发展方向应是无论选择何种技术来冷却光伏板,都应该保持工作表面温度较低且稳定、简单可靠、能够利用提取的热能来提高整体的转换效率。     

A review on the performance of photovoltaic/thermoelectric hybrid generators

Utilization of a broad range of solar spectrum has the potential for high power output from solar cells. However, solar photovoltaics (PVs) can convert only part of the solar electromagnetic spectrum into electricity efficiently. The remaining of the solar radiation is often dissipated in the form of heat, which causes performance reduction and reduces the life expectancy of the solar PV cell. Thermoelectric generators (TEGs) are devices that operate like a heat engine by converting thermal energy into electricity through thermoelectric effect. Integrating a TEG into a PV converter will enhance its efficiency and reduce the amount of heat dissipated. Different studies have been carried out and are still taking place to increase the total efficiency of a coupled photovoltaic thermoelectric generator (PV-TEG) system. This review discusses the concept of PV converters and thermoelectric devices and presents the various models and numerical and experimental investigations on performance enhancement of integrated PV-TEGs. The influence of key parameters on the performance of PV-TEG were also discussed. The review is expected to serve as a reference to recent work on research and development of integrated PV-TEG systems.     

Energy storage-based power buffering control for photovoltaic power generation system

光伏发电系统输出的最大功率随外界环境变化而波动,无法满足负荷的供电需求,针对该问题,建立了基于储能系统的光伏发电系统结构,介绍了光伏发电系统运行原理,分析了系统功率与直流母线电压的关系,设计了无源式储能系统和有源式储能系统对功率进行缓冲以满足控制目标.仿真结果表明,有源式储能系统较无源式储能系统有更好的功率调节作用,通过双向DC-DC变换器的储放能量自动切换控制,使得光伏发电系统输出的功率与负荷需求功率良好匹配,直流电压稳定.     

Performance improvement study of an integrated photovoltaic system for offshore power production

Sustainable energy is one of the main options for resolving energy problems and climate change issues. Solar energy is one of the main promising renewable energy sources, which can be captured and converted to electrical energy through photovoltaic (PV) panels. In the open literature, it is shown that having two PV panels integrated into a back‐to‐back configuration placed on naturally reflective surfaces provides the potential of doubling the total power produced by a single‐faced PV panel with the appropriate location and orientation. This paper presents a case study of two‐PV panel systems for offshore power production. The relevance to offshore has the water surface as the reflective surface to produce power from the back facing panel. The city of Ottawa in Canada is selected as the location for a case study. Various conditions and operating parameters are considered in assessing the performance of the proposed system, including solar radiation intensity, system orientation, time of year in terms of months, and the variations in parameters throughout the day. The assessment of the proposed system is carried out through modeling and simulating the proposed double PV panels in the COMSOL Multiphysics software. It is found that the minimum improvement in the total power production over the single face conventional PV is 38% in January for the east‐facing PV front face. For the two PV systems, the optimal overall power production for the various time conditions and orientations, at the specified location, is found to be the north orientation of the PV panel. In this case, the power it produces is 89% of that of the east orientation. A similar trend is observed for the single‐faced PV panel, where the north‐facing PV provides 62% of what it could produce in the east‐facing orientation.     

Determinant factors in site selection for photovoltaic projects: A systematic review

The choice of great places for installation of solar power plants has become a key issue in terms of project planning because of the increased number of investments in the photovoltaic sector. This study is a systematic review of the literature that seeks to identify the determining factors in choosing the best location for solar photovoltaic power plants, through previous research on the application of renewable energy technologies in great contexts of location. Among a total of 130 academic studies filtered by the keywords “photovoltaic energy,” “power plants,” “location,” and “factor” on the bases ScienceDirect, Scopus, Web of Science, and IEEE, a total of 27 studies were identified. These articles were carefully explored, including years of publication, countries of origin, and identification of factors that each author demonstrated. It has been extracted 28 factors, organized in six points of view: socioenvironmental, location, economic, political, climatic, and orographic. It was verified that the determining factors for choosing the best locations are solar irradiation, substation distance, slope, distance of roads, distance from urban areas, and land use. The results of this research may assist academic students and investors in identifying factors that they should consider in their decision making and may also assist in the efficient planning of renewable energy management to ensure the sustainable development of power generation through the photovoltaic source.     

Comparative study to use nanofluid ZnO and CuO with phase change material in photovoltaic thermal system

In this study, the simultaneous use of nanofluid and phase changing material as a coolant for photovoltaic fluid collector system and its effects are investigated experimentally. Two types of nanofluid are taken for the consideration, that is, ZnO and CuO, which are water‐based fluid. The experiments are performed in five different types of photovoltaic thermal system conventional: PT, PVT (ZnO), PVT (CuO), PCM medium (PVT/PCM/ZnO), and PCM medium (PVT/PCM/CuO). The results are obtained for surface temperature, energy, and thermal efficiency, and it is compared with each other. Further, the effect of the nanofluid as the effective alternative for pure deionized water is measured. From the results, it is evident that the PVT/PCM/CuO system minted 15% high electric output compared with convention module. Furthermore, the addition of the CuO nanofluid increases the thermal output significantly up to 8% for PVT and 12% for PCM without energy consumption. It also found that the nanofluid increases the overall energy efficiency of the system compared with convention PV.     

A comprehensive optimized model for on‐board solar photovoltaic system for plug‐in electric vehicles: energy and economic impacts

Environmental concerns along with high energy demand in transportation are leading to major development in sustainable transportation technologies, not the least of which is the utilization of clean energy sources. Solar energy as an auxiliary power source of on‐board fuel has not been extensively investigated. This study focuses on the energy and economic aspects of optimizing and hybridizing, the conventional energy path of plug‐in electric vehicles (EVs) using solar energy by means of on‐board photovoltaic (PV) system as an auxiliary fuel source. This study is novel in that the authors (i) modeled the comprehensive on‐board PV system for plug‐in EV; (ii) optimized various design parameters for optimum well‐to‐tank efficiency (solar energy to battery bank); (iii) estimated hybrid solar plug‐in EVs energy generation and consumption, as well as pure solar PV daily range extender; and (iv) estimated the economic return of investment (ROI) value of adding on‐board PVs for plug‐in EVs under different cost scenarios, driving locations, and vehicle specifications. For this study, two months in two US cities were selected, which represent the extremities in terms of available solar energy; June in Phoenix, Arizona and December in Boston, Massachusetts to represent the driving conditions in all the US states at any time followed by assessment of the results worldwide. The results show that, by adding on‐board PVs to cover less than 50% (around 3.2 m²) of the projected horizontal surface area of a typical passenger EV, the daily driving range could be extended from 3.0 miles to 62.5 miles by solar energy based on vehicle specifications, locations, season, and total time the EV remains at Sun. In addition, the ROI of adding PVs on‐board with EV over its lifetime shows only small negative values (larger than ?45%) when the price of electricity remains below Environmental concerns along with high energy demand in transportation are leading to major development in sustainable transportation technologies, not the least of which is the utilization of clean energy sources. Solar energy as an auxiliary power source of on‐board fuel has not been extensively investigated. This study focuses on the energy and economic aspects of optimizing and hybridizing, the conventional energy path of plug‐in electric vehicles (EVs) using solar energy by means of on‐board photovoltaic (PV) system as an auxiliary fuel source. This study is novel in that the authors (i) modeled the comprehensive on‐board PV system for plug‐in EV; (ii) optimized various design parameters for optimum well‐to‐tank efficiency (solar energy to battery bank); (iii) estimated hybrid solar plug‐in EVs energy generation and consumption, as well as pure solar PV daily range extender; and (iv) estimated the economic return of investment (ROI) value of adding on‐board PVs for plug‐in EVs under different cost scenarios, driving locations, and vehicle specifications. For this study, two months in two US cities were selected, which represent the extremities in terms of available solar energy; June in Phoenix, Arizona and December in Boston, Massachusetts to represent the driving conditions in all the US states at any time followed by assessment of the results worldwide. The results show that, by adding on‐board PVs to cover less than 50% (around 3.2 m²) of the projected horizontal surface area of a typical passenger EV, the daily driving range could be extended from 3.0 miles to 62.5 miles by solar energy based on vehicle specifications, locations, season, and total time the EV remains at Sun. In addition, the ROI of adding PVs on‐board with EV over its lifetime shows only small negative values (larger than ?45%) when the price of electricity remains below $0.18/kWh and the vehicle is driven in low‐solar energy area (e.g. Massachusetts in the US and majority of Europe countries). The ROI is more than 148% if the vehicle is driven in high‐solar energy area (e.g. Arizona in the US, most Africa countries, Middle East, and Mumbai in India), even if the electricity price remains low. For high electricity price regions ($0.35/kWh), the ROI is positive and high under all driving scenarios (above 560%). Also, the reported system has the potential to reduce electricity consumption from grid by around 4.5 to 21.0 MWh per EV lifetime. A sensitivity analysis has been carried out, in order to study the impacts of the car parked in the shade on the results. Copyright © 2016 John Wiley & Sons, Ltd.     

太阳能光伏光热一体化系统的实验研究

为提高太阳能的利用率同时得到可资利用的热水和电力，将小型贮能式光伏系统与家用平板型太阳能热水器结合起来，把光优电池组件层压在热水器的扁盒式铝合金集热板上，构成一套光优光热(PV／T)一体化系统，并在合肥地区进行了自然循环模式下的光电光热性能测试。实验结果表明，在晴朗或多云的天气条件下实验系统日平均热效率可达40％，日平均发电效率约9．5％，系统综合性能效率多在60％以上，比单独的光伏或热水系统效率有显著提高。     

A novel method to optimize photovoltaic generator operation

Photovoltaic (PV) energy is an alternative energy source for the future due to the world's limited energy resources. In this paper, a new technique to improve the performance of a PV array is presented. The study is based on the determination of the optimal configuration of a PV generator for a fixed number of modules. The aim of the study is to extract the maximum power from a PV generator connected in a direct coupling to a load. Different considerations (commutation current alone, commutation voltage alone, commutation current and voltage) are described. The presented method is based on microcontroller utilization. Very simple calculations allowed to decide, in real time, which configuration is appropriate for any load and any work conditions. Theoretical and experimental results are included. The effectiveness of the applied method is assessed by simulations and experiments. The method using commutation current and commutation voltage leads to good results unlike the other techniques. Copyright © 2008 John Wiley & Sons, Ltd.     

Solar energy—A look into power generation,challenges, and a solar‐powered future

Sun is an inexhaustible source of energy capable of fulfilling all the energy needs of humankind. The energy from the sun can be converted into electricity or used directly. Electricity can be generated from solar energy either directly using photovoltaic (PV) cells or indirectly using concentrated solar power (CSP) technology. Progress has been made to raise the efficiency of the PV solar cells that can now reach up to approximately 34.1% in multi‐junction PV cells. Electricity generation from concentrated solar technologies has a promising future as well, especially the CSP, because of its high capacity, efficiency, and energy storage capability. Solar energy also has direct application in agriculture primarily for water treatment and irrigation. Solar energy is being used to power the vehicles and for domestic purposes such as space heating and cooking. The most exciting possibility for solar energy is satellite power station that will be transmitting electrical energy from the solar panels in space to Earth via microwave beams. Solar energy has a bright future because of the technological advancement in this field and its environment‐friendly nature. The biggest challenge however facing the solar energy future is its unavailability all‐round the year, coupled with its high capital cost and scarcity of the materials for PV cells. These challenges can be met by developing an efficient energy storage system and developing cheap, efficient, and abundant PV solar cells. This article discusses the solar energy system as a whole and provides a comprehensive review on the direct and the indirect ways to produce electricity from solar energy and the direct uses of solar energy. The state‐of‐the‐art procedures being employed for PV characterization and performance rating have been summarized . Moreover, the technical, economic, environmental, and storage‐related challenges are discussed with possible solutions. Furthermore, a comprehensive list of future potential research directions in the field of direct and indirect electricity generation from solar energy is proposed.     

光伏接入配电网线路故障特征及保护方案的研究

光伏系统接入配电网后,配电网供电模式发生变化,导致配电网部分继电保护设备不能正确动作。根据储能充放电原理,在光伏输出直流侧并入储能模块抑制光伏功率波动,确保配电网接受光伏功率保持恒定,进而提出适用于光伏接入配电网线路电流保护的整定方法,该方法能够解决光伏接入点反向出口短路电流值大小随光伏输出功率波动的问题。在PSCAD/EMTDC中建立了储能型光伏接入10 k V配电网算例模型,通过仿真验证了该方法的正确性与有效性。     

Analysis of output power smoothing method of the solar chimney power generating system

Severe fluctuation of the output power is a common problem in the generating systems of various renewable energies. The concept of output power fluctuation factor of renewable energy power generating systems was put forward in this paper. Aiming to decrease the fluctuation factor of output power in solar chimney power generating systems (SC), a novel hybrid energy storage system made of water, and sandstone was employed to replace the traditional sandstone energy storage system. The mathematical models of fluid flow, heat transfer and power generating features of SC were established and the influences of material, depth, areas and location of the energy storage layer upon output power were analyzed. The simulation results indicated that adopting the hybrid energy storage of water and sandstone can effectively decrease the fluctuation factor of SC output power and hence smooth the SC output power. In addition, according to the largest daily power generating capability or the smallest peak fluctuation factor, the corresponding optimum depth of the water energy storage layer would be 5 cm or 20 cm, respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

Investigating the performance of a water-based photovoltaic/thermal (PV/T) collector in laminar and turbulent flow regime

The objective of this work is to simulate a water-based flat plate photovoltaic/thermal system with glass cover and without it in laminar and turbulent regime and investigating the effects of solar irradiation, packing factor, Reynolds number, collector length, pipes diameter and number of pipes on the performance of this system. The accuracy of the model has been validated with the available data in the literature, where good agreements between the results have been achieved. The results showed that the energy efficiency in the glazed photovoltaic/thermal system is higher than unglazed one, while its exergy efficiency depends on the packing factor, Reynolds number and collector length. The results also indicated that increasing of solar radiation and packing factor increases total energy and exergy efficiency in both laminar and turbulent regime. Besides, it was found that there are the optimum values for mass flow rate and number of pipes that maximize exergy efficiency. The value of the optimum mass flow rate is larger in the case of unglazed system compared to that of glazed one. Furthermore, in most cases, the total energy efficiency in turbulent regime is higher, whereas the total exergy efficiency in laminar regime is superior.     

A new integrated single‐diode solar cell model for photovoltaic power prediction with experimental validation under real outdoor conditions

The output power prediction by a photovoltaic (PV) system is an important research area for which different techniques have been used. Solar cell modeling is one of the most used methods for power prediction, the accuracy of which strongly depends on the selection of cell parameters. In this study, a new integrated single‐diode solar cell model based on three, four, and five solar cell parameters is developed for the prediction of PV power generation. The experimental validation of the predicted results is done under outdoor climatic conditions for an Indian location. The predicted power by three models is found close to measured values within 4.29% to 4.76% accuracy range. The comparative power estimation analysis by these models shows that the three‐parameter model gives higher accuracy for low solar irradiance values <150 W/m², the four‐parameter model in the range of 150 to 500 W/m², and the five‐parameter model for >500 W/m². The present model is also compared with other models in literature and is found to be more accurate with less percentage error. The overall results also show that the power produced depends on temperature and solar radiation levels at a particular location. Thus, single solar cell model developed can be used with sufficient accuracy for power forecast of PV systems for any location worldwide. The follow‐up research areas are also identified.     

Uniqueness verification of direct solar spectral index for estimating outdoor performance of concentrator photovoltaic systems

To analyze the impact of a direct spectral distribution of the solar spectrum on the outdoor performance of concentrator photovoltaic (CPV) systems, an index for the direct spectral distribution is needed. Average photon energy (APE), the average energy of a photon in the direct solar spectrum, is one of these indexes. In this contribution, the uniqueness of APE to the direct solar spectral distribution is statistically analyzed to assure that an APE value uniquely yields the shape of a direct solar radiation spectrum. The results have exhibited the uniqueness of the direct normal solar spectrum with each APE value, in which the standard deviations are quite small. Short-circuit current density of the InGaP/InGaAs/Ge triple-junction solar cell in the CPV system is additionally calculated using the direct spectral irradiance with different APE values. It is revealed that APE is a useful index to describe the direct spectral distribution to evaluate the outdoor performance of the CPV systems.