Environmental Impacts of Grid Connected High Concentrated Photovoltaic Systems Adapted for Peak Load Minimization in Hot Climate

High concentrated PV multi-junction solar cells (HCPV) likely present a favorable alternative to achieve low cost of energy. However, multi-junction solar cell has different characteristics which should be settled before they can be adapted for large scale energy generation. Peak energy consumption in Kuwait usually occurs in periods of utilizing air conditioning systems which are essentially used in almost all year around in harsh climate like Kuwait. Power consumed at peak times is more costly than power needed to satisfy loads at regular consumption times. The main goal of the present research is to increase HCPV solar cells’ efficiency, to decrease maximum power cost in Kuwait. Multi-junction solar cells performance in weather conditions of Kuwait is investigated employing a single diode equivalent circuit model. The model developed considers the impacts of concentration ratio as well as temperature. Most research in literature review usually neglects shunt resistance of the diode, however this resistance is taken into consideration in current developed theoretical model. To calibrate the present model, current predictions are compared with corresponding measured data provided by multi-junction solar cell manufacturer. The total root mean square errors in the present model predictions are about 1.8%. This means that current developed model of single diode model which takes into account shunt resistance impacts gives precise and reliable data. HCP electrical efficiency is noticed to rise as concentration increases but to a certain concentration value, then it begins to decrease. In addition, utilizing HCPV linked to grid satisfies great decrease in maximum load. Power produced from HCPV modules is utilized to provide energy needs to a family in normal Kuwaiti family home to evaluate HCPV environmental effects. HCPV modules slopes and areas are changed to accomplish peak energy production all over the year. Present results reveal that optimum power production corresponds to HCPV modules directed to south and having latitude of 25°. In addition, employing HCPV modules can avoid approximately 1.55 ton of emitted CO2 per year. In conclusion, current work reveals the advantage impacts of grid connected HCPV in Kuwait weather.

Practical Realization of a Hybrid Solution for Photovoltaic and Photothermal Conversion

In this paper, an idea and a realization of a hybrid Operational solar system is presented and practically verified discussed on the base of the performance and efficiency results, is confirmed. solution for photovoltaic and photothermal conversion is presented. by the series of experiments. Improvements of the construction are The synergy effect ofphotothermal and photovoltaic part cooperation

Design of Reflective Concentrator Model with Application for Concentrator Photovoltaic System

The nonuniform irradiation in the standard photovoltaic（PV） cells causes their relatively high series resistance,which results in a considerably lowered efficiency of PV cells.Currently the concentrator of uniform irradiation designed for concentrator photovoltaic is rare in China and lack sufficient theoretical research.In this paper,a systematic research on the solar reflective concentrator is conducted.A novel structure for a solar reflective concentrator is designed with the application of a flat mirror matrix to concentrate the sunlight for concentrator photovoltaic（CPV） systems.Sunlight beams are focused through the reflection of the mirror array on the solar cell to generate electricity.The concentrator is capable of producing much more uniform sunlight with a certain concentration ratio.The design scheme includes laying out the flat mirrors,optimizing the optical pathway and the parameters of each mirror.The prototype of the CPV system was installed at Nanjing,China.In the configuration of the prototype,it is composed of 24 pieces parallelogram flat mirrors,which are arranged into a total reflective array of 5 rows and 5 columns.In comparison with the parabolic trough concentrator,the experimental measurements verify such design has high efficiency.The concentrator model of a flat mirror matrix and the proposed new design method will lay a solid foundation for designing the concentrator of uniform irradiation.

Performance Analysis of Compound Parabolic Concentration Photothermal and Photoelectricity Device for Soil Heating in Facility Agriculture

It is difficult for solanum crops to grow continuously during winter in severe cold regions. Thus, a soil heating system for facility agriculture based on solar concentration technology was proposed, and a novel compound parabolic concentration photothermal and photoelectricity device(CTPV) equipped in the system was designed to address this problem. In accordance with the structure of the device, LightTools optical software was selected to analyze the variation trend of the light escape rate of the device with the diff erent incident angles. On the basis of the calculation results, an experimental test system was used to investigate the relationship of the air temperature of the inlet and the outlet, total output power of the solar cells, and photothermal and photoelectricity efficiency of the device with the operation time during a sunny day. Research results reveal that the light escape rate of the device is 5.36% at an incidence angle of 12°. At a velocity of 1.5 m/s, the maximum air temperature of the outlet can reach 55.6 ℃, and the total output power of the solar cells is 474.4 W. The variation of the total power of the solar cells is consistent with the simulation results. The maximum instantaneous heat collection and the maximum photothermal and photoelectricity efficiency of the device are 306 W and 60.4%, respectively, and the average efficiency is 44.9%. This study can serve as a reference for compound parabolic concentration technology applied for soil heating in facility agricultural soil heating systems.

Spectrum-Splitting Diffractive Optical Element of High Concentration Factor and High Optical Efficiency for Three-Junction Photovoltaics

A spectrum-splitting and beam-concentrating （SSBC） diffractive optical element （DOE） for three-junction pho- tovoltaics （PV） system is designed and fabricated by five-circ/e micro-fabrication. The incident solar light is efficiently split into three sub-spectrum ranges and strongly concentrated on the focal plane, which can be di- rectly utilized by suitable spectrum-matching solar cells. The system concentration factor reaches 12x. Moreover, the designed wavelengths （450nm, 550nm and 65Onto） are spatially distributed on the focal plane, in good agree- ment with the theoretical results. The average optical effic/ency of all the cells over the three designed wavelengths is 60.07%. The SSBC DOE with a high concentration factor and a high optical efficiency provides a cost-effective approach to achieve higher PV conversion efficieneies.

Performance Improving of a Concentrating Photovoltaic System by Using a New Optical Adhesive

The objective of this present study is to manufacture a new silicone-based adhesive which is used for gluing and bonding the second optical elements (SOE) with Concentrating Photovoltaic solar cell (CPV) in order to guarantee a thickness that can provide a good silicone adherence to obtain long term stability and keeping a good solar transmittance performance, too. This new adhesive is made up of a mixture of silicone and transparent glass balls. The experimental part consists of the choice of the best size of glass balls with the suitable proportion of the glass balls weight in the mixture. For this purpose, ten samples were manufactured for every category of glass balls and weight ratio. Glass ball sizes between 100 and 1100 μm, and weight ratios between 1 and 10% were analyzed. For each category of glass balls, four proportions were mixed with the silicone. The thicknesses and transmittance of every sample were measured with appropriate instruments. The experimental results illustrate that the mixture containing balls with sizes inferior to 106 μm, is the best mixture which assures adhesive minimum thickness value necessary for an efficient mechanical bond and preserves also a good transmittance of solar irradiance.

Experimental evaluation of factors affecting performance of concentrating photovoltaic/thermal system integrated with phase‐change materials(PV/T‐CPCM)

The photovoltaic/thermal(PV/T)system is a promising option for countering energy shortages.To improve the performance of PV/T systems,compound parabolic concentrators(CPCs)and phase-change materials(PCMs)were jointly applied to construct a concentrating photovoltaic/thermal system integrated with phase-change materials(PV/T-CPCM).An open-air environment is used to analyze the effects of different parameters and the intermittent operation strategy on the system performance.The results indicate that the short-circuit current and open-circuit voltage are positively correlated with the solar irradiance,but the open-circuit voltage is negatively correlated with the temperature of the PV modules.When the solar irradiance is 500 W⋅m^(−2) and the temperature of the PV modules is 27.5℃,the short-circuit current and open-circuit voltage are 1.0 A and 44.5 V,respectively.Higher solar irradiance results in higher thermal power,whereas the thermal efficiency is under lower solar irradiance(136.2-167.1 W⋅m^(−2) is twice under higher solar irradiance(272.3-455.7 W⋅m^(−2))).In addition,a higher mass flow rate corresponds to a better cooling effect and greater pump energy consumption.When the mass flow rate increases from 0.01 to 0.02 kg⋅s^(-1),the temperature difference between the inlet and outlet decreases by 1.8℃,and the primary energy-saving efficiency decreases by 0.53%.The intermittent operation of a water pump can reduce the energy consumption of the system,and the combination of liquid cooling with PCMs provides better thermal regulation and energy-saving effects under various conditions.

Magnetophotothermal interaction in a rotating solid cylinder of semiconductor silicone material with time dependent heat flow

A mathematical model linking thermoelasticity to photothermal experiments is proposed with the consideration of the photothermal effect.The system equations for coupled plasma,heat conduction with phase-lags(PLs),and motion equations are introduced and solved by using the Laplace transform technique.The photothermal,thermal,and elastic waves in a rotating solid cylinder of semiconductor material are analyzed with the proposed model.The cylinder surface is constrained and subjected to a time-dependent pulse heat flux.The sensitivity of the physical fields for the angular velocity,PLs,and thermal vibration parameters is investigated.In addition,the effects of the effective parameters on the physical quantities are graphically illustrated and discussed in detail.

Defect physics of the quasi-two-dimensional photovoltaic semiconductor GeSe

GeSe has recently emerged as a photovoltaic absorber material due to its attractive optical and electrical properties as well as earth abundancy and low toxicity.However,the efficiency of GeSe thin-film solar cells(TFSCs)is still low compared to the Shockley–Queisser limit.Point defects are believed to play important roles in the electrical and optical properties of GeSe thin films.Here,we perform first-principles calculations to study the defect characteristics of GeSe.Our results demonstrate that no matter under the Ge-rich or Se-rich condition,the Fermi level is always located near the valence band edge,leading to the p-type conductivity of undoped samples.Under Se-rich condition,the Ge vacancy(V_(Ge))has the lowest formation energy,with a(0/2–)charge-state transition level at 0.22 eV above the valence band edge.The high density(above 10^(17)cm^(-3))and shallow level of VGeimply that it is the p-type origin of GeSe.Under Se-rich growth condition,Seihas a low formation energy in the neutral state,but it does not introduce any defect level in the band gap,suggesting that it neither contributes to electrical conductivity nor induces non-radiative recombination.In addition,Gei introduces a deep charge-state transition level,making it a possible recombination center.Therefore,we propose that the Se-rich condition should be adopted to fabricate high-efficiency GeSe solar cells.

Adapting Integrated High Concentrated PV Modules and Evacuated Tube Collectors to Minimize Building Energy Consumption in Hot Climate

Energy consumption in buildings is considered a significant portion of gross power dissipation, so a great effort is required to design efficient construction. In severe hot weather conditions as Kuwait, energy required for building cooling and heating results in a huge energy loads and consumption and accordingly high emission rates of carbon dioxide. So, the main purpose of the current work is to convert the existing institutional building to near net-zero energy building (nNZEB) or into a net-zero energy building (NZEB). A combination of integrated high concentrated photovoltaic (HCPV) solar modules and evacuated tube collectors (ETC) are proposed to provide domestic water heating, electricity load as well as cooling consumption of an institutional facility. An equivalent circuit model for single diode is implemented to evaluate triple junction HCPV modules efficiency considering concentration level and temperature effects. A code compatible with TRNSYS subroutines is introduced to optimize evacuated tube collector efficiency. The developed models are validated through comparison with experimental data available from literature. The efficiency of integrated HCPV-ETC unit is optimized by varying the different system parameters. Transient simulation program (TRNSYS) is adapted to determine the performance of various parts of HCPV-ETC system. Furthermore, a theoretical code is introduced to evaluate the environmental effects of the proposed building when integrated with renewable energy systems. The integrated HCPV-ETC fully satisfies the energy required for building lighting and equipment. Utilizing HCPV modules of orientation 25? accomplishes a minimum energy payback time of about 8 years. Integrated solar absorption chiller provides about 64% of the annual air conditioning consumption needed for the studied building. The energy payback period (EPT) or solar cooling system is about 18 years which is significantly larger than that corresponding to HCPV due to the extra expenses of solar absorption system. The life cycle savings (LCS) of solar cooling absorption system is approximately $2400/year. Furthermore, levelized cost of energy of solar absorption cooling is $0.21/kWh. Hence, the net cost of the solar system after subtracting the CO2 emission cost will be close to the present price of conventional generation in Kuwait (about $0.17/kWh). Finally, the yearly CO2 emission avoided is approximately 543 ton verifying the environmental benefits of integrated HCPV-ETC arrangements in Kuwait.

基于光热光伏耦合供能新型复合抛物面聚光器性能探究

非跟踪式复合抛物面聚光器瞬时集热量受入射偏角影响较大。文章通过在传统复合抛物面聚光器焦斑上方布置板背面为镜面的光伏组件,实现对逸出光线的再次利用,提高了装置的太阳能转化效率。利用光学软件对基于光热、光伏耦合供能新型复合抛物面聚光器进行了光线追迹,对比分析了径向入射偏角对光线接收率的影响。在实际环境中,测试、研究了新型复合抛物面聚光器进、出口温度、瞬时集热量、输出电功率等随时间的变化规律。结果表明,新型复合抛物面聚光器与传统复合抛物面聚光器的光线接收率随入射偏角变化趋势一致,当径向入射偏角为20°时,新型复合抛物面聚光器的光线接收率为89.00%,比传统复合抛物面聚光器增加了72.82%。在晴天集热中,新型复合抛物面聚光器最大出口温度为34.2℃,最大光热转化效率为73.40%,日输出电功率为118.40 W。

基于聚光光伏光热的太阳能供暖系统性能优化

以北京市某办公建筑为供暖对象,提出由聚光光伏光热单元、光伏单元以及空气源热泵(CPVT-PV-ASHP)耦合的清洁供暖系统。基于Trnsys和Grasshopper平台搭建系统的动态仿真模型和优化模型,以CPVT光伏电池板面积为决策变量,采用超体积计算法(HypE)求解,探究系统在节能性、经济性和改善热泵性能方面的平衡。结果显示,在空冷型CPVT和水冷型CPVT中光伏电池板面积分别为10.9 m^(2)和2.3 m^(2)时取得最优解。此时系统的一次能源消耗量为-1 016.1千克标准煤,热泵平均能效比(COP)为3.72,投资回报周期为2.95年。与其他系统相比,CPVT-PV-ASHP系统在节约能耗、改善热泵性能等方面优势显著。

基于模型-数据联合的光伏-光热系统储能量预测

提出一种模型-数据联合预测方法,通过机理分析建立对象动态模型,并引入未来太阳辐射强度、用户负荷预测数据进行即时模型预测,通过注意力机制改进的卷积-长短时记忆混合神经网络建立数据预测模型,并引入历史数据进行滚动数据预测,然后利用卡尔曼滤波器对2种预测模型的输出结果进行融合,实现储能量的联合预测。结果表明:联合预测兼具2种方法的优势,能很好地解决储能量预测误差随时间累积的问题,并能够及时表征气象因素突变和系统运行方式改变时储能量的变化情况,在各种天气状况下均具有良好的预测精度。

光热与光伏发电综合对比

光伏发电和光热发电是太阳能发电的2种典型形式。光伏开发成本相对较低,但为保证系统安全稳定运行,须配置一定比例储能和分布式调相机,造成发电成本提升,而光热自带储热和出力友好性,因此目前对于光伏与光热的发展技术路线仍存在较大争议。文中以青海海西地区为例,基于同一时空太阳能辐照资源和出力特性,比较光伏+储能与光热的电力保障能力;然后从电网安全稳定支撑能力角度对光伏+储能+调相机与光热进行比较;最后基于光热和光伏成本下降趋势预测进行二者的经济性对比。研究结果表明,若将光热和光伏放到技术对等层面,则光热由于同时具备储热和常规发电机功能,能够为系统提供短路容量、无功补偿和转动惯量支撑,在成本下降后经济性与光伏+储能+调相机基本相当,甚至更优。

双流体型光伏光热屋顶组件的热、电性能实验研究

文中提出一种无盖板的双流体型光伏光热屋顶组件,通过将管板式水冷流道与折流板式空冷流道组合,降低组件水容量、提升空气出口温度,实现组件热水、热空气两种热能形式的供应。通过搭建具有稳定测试环境的性能测试试验台,研究组件工质进出口温差、光伏电池温度等随太阳辐照度、工质流量的变化情况,对组件全天热、电性能进行分析。结果表明,该组件光伏电池冷却效果明显,水冷、空冷模式下电效率最高可达16.8%、17.6%,拥有较高的全天综合性能,全天综合利用率最高为74%。

基于太阳能分频利用的光伏/光热综合发电系统热力学分析

通过对太阳能聚光投入辐射进行分频,建立光伏与光热驱动有机朗肯循环综合供电系统。在冷却背板温度100℃的限制下,对该系统进行热力学分析,筛选了适宜的循环工质,获得了有机朗肯循环(ORC)系统优化的蒸发温度。结果表明:isobutene作为光伏系统的冷却工质和ORC系统的循环工质时系统效率最高,分频技术将冷却背板散热负荷转移至集热器,可降低光伏板的散热需求,从而降低循环工质质量流量,对提高系统发电能力有积极作用,该系统可将单纯光伏发电效率提高9百分点;同时,分频效率和太阳能电池吸收波段对综合供电系统的总效率影响较大。

基于热管的光伏冷却技术研究进展

光伏发电技术的发展和推广是实现碳中和的关键途径之一,但传统光伏电池效率会随自身温度升高而下降,故采取冷却措施降低其温度成为光伏领域的热点问题,其中具有结构简单、传热效率高、可塑性强、被动运行等优点的热管近年来受到了重点关注,而相关研究现状尚待分析汇总.本文从不同热管类型的视角对该领域进行了深入探讨,涵盖热管及其与天空辐射制冷、相变储能、热电制冷和纳米技术耦合下的多种冷却方式,并结合基于热管的光伏冷却技术的发展现状讨论其系统性能、经济和环境效益,对该研究方向进行了展望.综合既有研究发现,热管冷却是一种环保、经济且可行的光伏冷却方式,能有效降低光伏温度并提升其均匀性,且在技术耦合下可实现太阳能与其他清洁能源的科学协同利用,提升其发电性能或实现制冷、储能等附加功能,其发展应用对推动节能减排事业有着积极意义.

建筑领域太阳能利用系统的性能、挑战及优化策略综述

建筑领域的太阳能利用技术包括太阳能热水系统、太阳能制冷与空调系统、太阳能热泵系统以及建筑一体化光伏/热系统(BIPV/T)。系统效率和储热是制约太阳能热水系统发展的关键因素,目前的研究主要侧重于优化系统效率,未来应进一步关注储热技术的进步,以解决太阳能热水系统热水供应稳定性的问题。太阳能制冷与空调系统重点关注降低太阳能集热系统成本、提高集热器性能并研发小型太阳能制冷设备。太阳能热泵技术具有高能源利用率和低环境污染的特点,目前在实际应用中面临的技术障碍包括系统集成与优化、高效太阳能收集器、热泵性能提升、季节性储能、可靠性与稳定性以及经济性与可扩展性等,其中系统集成与优化尤为关键。太阳能光伏光热综合应用是建筑节能领域的一个重要研究方向,太阳能聚光光伏/光热系统(CPV/T)是解决BIPV/T系统中太阳能利用率低下问题的有效策略。BIPV/T和CPV/T系统还需要深入探讨集热器优化设计、材料选择、气候适应性及可持续性等问题。总之,未来建筑领域太阳能系统利用的主要研究方向为提高系统性能、开发新型材料以及集成优化。此外,应用物联网、大数据和人工智能技术可以促进太阳能系统的智能化监测、控制和维护。

光伏-塔式光热SCO_(2)混合发电系统优化配置

针对现阶段光热发电系统成本较高和光伏发电功率波动性大的问题,提出了光伏-塔式光热超临界二氧化碳布雷顿循环(SCO_(2))混合发电系统,研究了系统关键配置参数对经济性-环保性的影响规律,基于不同负荷类型对系统参数配置进行了多目标优化,探索了不同应用场景下混合发电系统的运行特性。仿真结果表明:光伏-塔式光热SCO_(2)混合发电系统中,光热发电比例升高时,系统经济性下降,但环保性能改善;增大混合发电系统总额定功率可降低系统平准化度电成本;当太阳倍数为4、储热时长为18 h情况下,平准化度电成本存在最低值为0.64元/(kW·h),比单纯光热发电经济性提高了31%。孤网运行条件下,在光伏-塔式光热SCO_(2)混合发电系统基础上增设柴油发电机组后,能够有效提升太阳能发电系统的供电可靠性,柴油发电占比仅为1.5%,柴油发电机组的年运行时长不足200 h即可保证100%满足实时电负荷需求。

低倍聚光光伏/光热与地源热泵集成系统综合分析及优化

将光伏/光热利用与地源热泵相互耦合,有望利用光伏余热避免热泵性能衰减,还可利用光伏电力部分满足热泵电能需求,前景广阔。构建了低倍聚光光伏/光热与地源热泵的集成系统运行仿真模型,对系统开展了运行性能分析;并进一步研究了系统全生命周期成本的关键影响规律。结果表明:集成系统光伏年均发电效率达17.73%,较单一运行系统提升9.58%,光伏/光热装置的光伏余热可有效减少土壤温度衰减,热泵长时运行性能较参比系统提升16.58%;系统运维成本随光伏/光热装置和地源热泵规模增加而减少,投资成本随之增加,总的全生命周期成本随规模增加先减后增;以全生命周期成本为目标函数,基于粒子群算法开展系统经济性优化,全生命周期成本较最大规模容量设计降低31.52%。相关结论可为光伏/光热与地源热泵集成系统优化设计提供理论参考。