气象要素对太阳能电池板温度的影响

温度升高会引起光伏电池发电效率下降,电池板温度是确定温度折减系数的必要条件,目前我国尚没有充足的外场实测电池板温度数据。该文基于北京南郊太阳能试验站2010年全年逐时电池板温度、气温、地表温度、斜面和水平辐照度实测数据,分析了电池板温度随时间的变化及其与各气象要素的关系。结果表明:电池板温度与气温和斜面辐照度的综合相关或与地表温度的线性相关最好,但实测数据不易获得;电池板温度与气温的线性相关较好,数据较易获得且质量有保证,从现实可行性考虑,是推算电池板温度最实用的相关方程;电池板温度与气温和水平辐照度的综合相关可以作为辅助方程,用于推算气温较高情况下的电池板温度。基于2010年电池板温度实测数据和加权计算的方法,得到北京地区年平均光伏发电温度折减系数约为2%,最高可达到13.3%。

太阳能-空气源复合热泵性能研究

为提高空气源热泵的低温适用性,通过在焓差试验室设定工况条件下进行试验,研究标准工况下3种太阳能热水温度与7种风机频率对太阳能-空气源复合热泵机组制热性能的影响。试验结果表明,在20 Hz变化到50 Hz风机频率的工况下,随着蒸发器通入太阳能热水水温的升高,机组制热量增加越明显,当通入30℃太阳能热水时,机组制热量比单一空气源热泵制热量平均可增加24.4%。通过不同环境工况下无太阳能热水与利用20℃太阳能热水条件的制热量对比,结果表明,随着环境温度降低,太阳能热水作用越明显。利用20℃热水时,在7种风机频率工况下,制热量平均增加23.3%。

分频北墙结构对日光温室内光热环境的影响

日光温室为中国特有的一种栽培设施结构,非对称的结构形式造成温室内南北光环境分布不均匀,一般墙体结构冬季夜间保温不能满足多数作物的生长需求。为构建具有保温蓄热能力、反射补光能力的多功能墙体结构,该研究设计了一种直接吸收太阳能的红外分频补光板(infrared frequency divided and supplementary light panel,IFDSLP),可对室内光热环境进行调节。合成了基于氧化锡锑(antimony tin oxide,ATO)-三氧化钨(tungsten trioxide,WO_(3))的水基纳米流体,将该纳米流体补充进IFDSLP内腔,作为传热分光工质。当IFDSLP集热面积为7.2 m^(2),光程为10 mm、体积分数为0.005%时,该流体工质在300~800 nm的植物光合有效波段中的平均反射率为79.6%,在近红外光波段中的平均吸收率为85.4%。该结构在增加温室北侧作物光照的同时,兼具温室夜间升温能力。IFDSLP系统的太阳能总利用率为71.9%,光热转换效率为36.4%,相比传统砖墙光辐射增加25%~28%,夜间空气温度平均提高1.5~2.0℃。该系统依托于现有日光温室结构,进一步改善了温室内的光热环境,是提高温室北墙全光谱利用率的有效途径。

Solar light,seawater temperature,and nutrients,which one is more important in affecting phytoplankton growth?

Based on research results on the impacts of solar light,seawater temperature,and nutrient available to phytoplankton growth and changes in phytoplankton physiology and assemblage,we discussed the order of influence of these factors.By clarifying the mechanisms and processes of the impacts by these factors,we have determined the rising order of the importance as solar light,seawater temperature,and nutrient silicon (Si).Therefore,for human interests in sustaining economic development,the first thing to be considered is the input of nutrient Si into the ocean,followed by seawater temperature change.

The Temperature Variation of a Solar Cell in Relation to Its Performance

The temperature of a solar cell subjected to the incident global solar radiation as a function of the local day time is determined. A heat balance equation is solved considering the heat losses due to convection and thermal radiation. The cell efficiency is estimated as a measure of its performance. The results reveal that the temperature within the cell attains significant values. Nevertheless, the temperature dependence of its efficiency along the day time is not pronouncing. It slightly decreases with temperature.

Control of Pavement-Surface Temperature-Rise Using Recycled Materials

High temperatures of the asphalt concrete pavements in summer contribute to the heat island phenomenon in the urban areas. The effective cool-pavement technologies are sought to mitigate the pavement environment. In this paper, developed heat-reflective pavements are constructed from open-graded asphalt concrete, in which voids in the upper part of the pavement are filled with a cement mortar, containing recycled materials as a fine aggregate. The recycled materials used in this study are： crushed oyster shells, roof tile debris, pottery debris, glass cullet, crushed escallops and coral sand. The temperature reduction of the pavement surfaces at an open site is measured in the summer. The results show that the maximum surface temperature of the pavements falls by approximately 8-10 ℃ compared to the asphalt concrete pavement. Furthermore, it is found that the temperature reduction is mainly due to the increased solar radiation reflectance of the pavement surface.

Energy Storage System for Solar Thermal Air Conditioning Combined with Ejector Cooling System

A system of energy storage for solar thermal air conditioning combined with ejector cooling system for residential is determined in this paper. The purpose of this study is to design the energy storage system for heating the water in a storage tank to reach the required temperature for exchanging heat with the refrigerant of cooling system. The design from calculation of thermal energy storage system that proper with the solar flat plate collector area results are 70 m2, and the hot water temperature is over than 80 ℃. A cooling system is selected for refrigerant of R141b from the solar air conditioning system of 10.5 kW, and the energy source is solar thermal energy from the collector that there is an efficiency of 0.46 approximately. This storage system for the electric solar cooling system can be reduced the problem of the intermittent of energy source with the constant generating temperature to run the cooling system continuously.

Effect of Substrate Temperature on Optical Characteristics of Silver Island Films for Harvesting Solar Energy

Due to their particular optical characteristics,metallic island films have the potential to significantly increase the energy conversion efficiency of solar cell.We experimentally and theoretically investigated the effect of substrate temperature on the morphologies and optical properties of the silver island films.At low temperature,below 300 ℃,as the substrate temperature increases.Compared to the films prepared at room temperature,the sizes of nanoparticles decrease and the Absorption peaks shift to shorter wavelength accompanied by an increase density resulting in a 150% Absorption efficiency.As the substrate temperature goes up to 300 ℃,nanoparticles with larger in-plan(X-Y)dimensions are formed,the number density decreases and the Absorption peaks redshift but the Absorption efficiency is still 10% higher.Numerical simulation reveals that these behaviors are a consequence of morphologies transformation.

Effect of Temperature on the Organic Solar Cells Parameters

The dependence of the organic solar cells parameters, e.g., the shirt circuit current Isc, open circuit voltage Vo,., the fill factor FF and the efficiency eta on temperature is investigated. By expressing the different equations which link the parameters with temperature, it is observed that the short circuit current Isc increases so monotonous with temperature and then saturates to a maximum value before decreasing at high temperatures. The open circuit voltage V∝ decreases linearly with the increasing of the temperature. The fill factor FF and the efficiency eta which are directly related with short circuit current Isc and the open circuit voltage V∝ follow their variations.

Variation of Quantum Efficiency in CZTSSe Solar Cells with Temperature and Bias Dependence by SCAPS Simulation

The quantum efficiency of CZTSSe （copper zinc tin sulphur selenium） thin film solar cells is numerically simulated at different temperatures and under a set of bias conditions about the efficiency limiting factors. A systematic methodology is developed and integrated into the proposed model to simulate the characteristics in the quantum efficiency. The proposed model is demonstrated with respect to an ideal device model under a set of bias conditions to selectively deactivate performance limiting parameters under light and voltage biased conditions. Under particular wavelength regions and bias conditions, a particular type of defects near the heterojunction interface significantly impact the carrier collection of devices. This deep acceptor type defect distribution is located in the band of ＋/- 0.3 eV from the midgap. These defect states influence CZTSSe spectral responses of red and IR light wavelength regions in quantum efficiency caused by affected depletion width toward the back contact. Therefore, the quantum efficiency of CZTSSe devices is altered disproportionally at biased conditions.

A new solution method for black-body radiation inversion and the solar area-temperature distribution

The effective temperature of the solar photosphere is usually obtained according to the solar constant, based on the Stefan-Boltzmann law. However its temperature distribution is not homogeneous. A hopeful way to obtain the area-temperature distribution of the solar photosphere is to solve the Black-body Radiation Inversion (BRI) problem. In this paper, a new practical solution method for BRI is developed. The theoretical analysis and numerical calculations show the low-temperature distribution difficulty of BRI is solved by this new method. Then the area-temperature distribution of the solar photosphere is obtained, according to the measured absolute solar spectral irradiance. It is the first realization of BRI for a real system after almost three decades of efforts. The results are comparable to that from the Stefan-Boltzmann law.

The influence of environment temperatures on single crystalline and polycrystalline silicon solar cell performance

The influence of the cell temperature (named interior environment temperature) and ambient air temperature (named exterior environment temperature) on the open-circuit voltage,short-circuit current,and output power has been carefully studied for the Si solar cells.The results show that one of the environment temperatures plays the major role,and the temperature dependence of device performance parameters is different for single crystalline and polycrystalline Si solar cells.Furthermore,the ambient air temperature builds a bridge for the comparison of the effect between the cell temperature and the illumination intensity on solar cell performance.Based on the experimental results,the reasons which cause the difference of the environment temperatures dependence are analyzed.

ZnO-PCBM bilayers as electron transport layers in low-temperature processed perovskite solar cells

We investigate an electron transport bilayer fabricated at 〈110℃ to form all low-temperature processed, thermally stable, efficient perovskite solar cells with negligible hysteresis. The components of the bilayer create a symbiosis that results in improved devices compared with either of the components being used in isolation. A sol-gel derived ZnO layer facilitates improved energy level alignment and enhanced charge carrier extraction and a [6,6]-phenyl-C61-butyric acid methyl ester （PCBM） layer to reduce hysteresis and enhance perovskite thermal stability. The creation of a bilayer structure allows materials that are inherently unsuitable to be in contact with the perovskite active layer to be used in efficient devices through simple surface modification strategies.

Thermodynamic analysis on medium-high temperature solar thermal systems with selective coatings

Thermodynamics analysis was carried out for solar thermal receivers with different selective coatings.The relation between the energy conversion efficiency of a medium-high temperature solar thermal system,the spectral properties of selective coating and the operating temperature of the receiver were discussed.Furthermore,the relation between the optimum operating temperatures,the exergy efficiencies and the incident solar flux were analyzed for the traditional concentrating system and concentrating beam splitting system,respectively.According to the analysis results for the thermal receiver with blackbody surface and selective coatings,the optimum cutoff wavelength was obtained for the ideal selective coating.An analysis method for the optimum operating temperature calculation was developed for thermal receivers with selective coating.The optimum operating temperature for an actual selective coating was analyzed on the basis of the proposed theory.

Optimal extent of fluorination enabling strong temperature-dependent aggregation, favorable blend morphology and high-efficiency polymer solar cells

Temperature-dependent aggregation is a key property for some donor polymers to realize favorable bulk-heterojunction(BHJ)morphologies and high-efficiency(>10%) polymer solar cells.Previous studies find that an important structural feature that enables such temperature-dependent aggregation property is the 2nd position branched alkyl chains sitting between two thiophene units.In this report,we demonstrate that an optimal extent of fluorination on the polymer backbone is a second essential structural feature that enables the strong temperature-dependent aggregation property.We compare the properties of three structurally similar polymers with 0,2 or 4 fluorine substitutions in each repeating unit through an in-depth morphological study.We show that the non-fluorinated polymer does not aggregate in solution(0.02 mg mL^(-1) in chlorobenzene) at room temperature,which results in poor polymer crystallinity and extremely large polymer domains.On the other hand,the polymer with four fluorine atoms in each repeating unit exhibits an excessively strong tendency to aggregate,which makes it difficult to process and causes a large domain.Only the polymer with two fluorine atoms in each repeating unit exhibits a suitable extent of temperature-dependent aggregation property.As a result,its blend film achieves a favorable morphology and high power conversion efficiency.This provides another key design rationale for developing donor polymers with suitable temperature-dependent aggregation properties and thus high performance.

Influence of annealing temperature of ZnO film as the electron transport layer on the performance of polymer solar cells

The surface morphology of Zn O films at different annealing temperatures and the performance of polymer solar cells(PSCs) with Zn O as the electron transport layer are studied.The low temperature sol-gel processed Zn O film has smoother surface than that in higher temperature,which results in the best photovoltaic performance with a power conversion efficiency(PCE) of 3.66% for P3HT:PC61BM based solar cell.With increasing annealing temperature,the photovoltaic performance first deceases and then increases.It could be ascribed to the synergy effects of interface area,the conductivity and surface energy of Zn O film and series resistance of devices.

A Mechanical and Experimental Study on the Heat Loss of Solar Evacuated Tube

The experimental system of heat loss of all-glass evacuated solar collector tubes(evacuated tube) is firstly designed and constructed,which uses electric heater as thermal resource.The equilibrium temperatures are less than±1℃during the test.and the temperature differences of up/middle/low node in the tube are less than 1℃,3℃,and 7℃respectively.The heat loss of evacuated tube increases about 2.7%with vacuum state of 0.01--1 mPa,and it has the best performance at tube temperature of 20--280℃.The invalidation tube(>200 mPa) has the biggest heat loss that increases linearly with the tube temperature.The evacuated tubes with the vacuum of 0.01-1 mPa are suitable for most solar adsorption refrigeration.

Design and thermal analysis of a water-cooled DSC module

Elevated working temperatures reduce the efficiency of dye-sensitized solar cells （DSCs）, and effective temperature regulation protects them from the undesirable efficiency loss. In this work, a semi-transparent DSC module equipped with a cooling sys- tem was designed and constructed for application in buildings, the temperature and output performance of the modules with or without cooling treatment were investigated. The test results showed the cooling system could noticeably improve the power generation and reduce the module temperature. Moreover, we established a mathematical model to analyze the modules＇ ther- mal performances, and introduced the concept of cooling efficiency to evaluate the cooling effect. The model accuracy have been validated utilizing measured data, and the effects of channel depth and mass flow rate on the module temperature and cooling efficiency were further theoretically studied. The combined DSC module has been found to have a good application prospect in building integrated photovoltaic （BIPV）, and the numerical results are important in system design.