Performance of off-grid residential solar photovoltaic power systems using five solar tracking modes in Kunming,China

This paper compares the performance of a 2.02 kW_p off-grid residential solar photovoltaic (PV) power system using PVSYST simulation software for a household in Kunming, Yunnan province, China. The monthly available solar energy; missing energy; array, final, and reference yields, performance ratio; and array capture and system losses were analyzed for five solar tracking modes: fixed tilted plane, seasonal tilt adjustment, horizontal axis tracking, vertical axis tracking, and dual axis tracking. Although there were some similar aspects across the five systems, minimum available solar energy (2461 kWh/y) and maximum missing energy (134.68 kWh/y) were obtained using the fixed tilted plane system (tilt angle = 25°, azimuth angle = 0°), whereas maximum available solar energy (3081 kWh/y) and minimum missing energy (48.53 kWh/y) in October were obtained using the dual axis tracking system. Average monthly performance ratio was maximal for the fixed tilted plane system (0.689), and minimal for the dual axis tracking system (0.596).     

Lead emissions from solar photovoltaic energy systems in China and India

China and India are embarking on ambitious initiatives over the next decade to expand solar photovoltaic (PV) power in underserved regions. China proposes adding 1.6 GW of solar capacity by 2020, while India plans 12 GW in addition to 20 million solar lanterns by 2022. These technologies rely heavily on lead-acid batteries (LABs) for storage. China and India’s lead mining, battery production, and recycling industries are relatively inefficient—33% and 22% environmental loss rates, respectively. Based on the quantity of lead batteries employed in existing PV systems, we estimate environmental lead emissions in China and India for new units installed under their solar energy goals. The average loss rates are 12 kg (China) and 8.5 kg (India) of lead lost per kW-year of installed PV capacity in these countries. The planned systems added in China and India will be responsible for 386 and 2030 kt of environmental lead loss, respectively, over their lifespan—equal to 1/3 of global lead production in 2009. Investments in environmental controls in lead smelting, battery manufacturing, and recycling industries along with improvements in battery take-back policies should complement deployment of solar PV systems to mitigate negative impacts of lead pollution.     

Study for improvement of solar cell efficiency by impurity photovoltaic effect

This paper is to study for efficiency improvement of solar cells by utilizing impurity traps introduced in the band gap of semiconductor, that is, impurity photovoltaic (IPV) effect. It is revealed theoretically that there is a certain energy range where impurity-traps act as stepping stones in two-step excitation of electrons from the valence band to the conduction band under suppression of carrier recombination through such traps. Indium is selected as one of proper impurities that satisfy this condition in crystalline silicon, and theoretical prediction is experimentally verified. A good agreement between theory and experiment is obtained concerned with photoconductive properties. It is concluded that the IPV effect is useful to improve the cell efficiency.     

Grid parity analysis of solar photovoltaic systems in Germany using experience curves

The paper starts with experience curve analysis in order to find out the future prices of solar photovoltaic (PV) modules. Experience curves for 75-90% progress ratio are extrapolated with the help of estimated future growth rate for PV installation worldwide and current module price data until year 2060. A kWh PV electricity generation cost has been calculated for coming decades with the help of local market parameters and module prices data from extrapolated experience curve. Two different prices for grid electricity - wholesale electricity price and end user electricity price - are separately analyzed. Household electricity consumption profile and PV electricity generation profile for Cologne, Germany, have been analyzed to find out the possibility for PV electricity consumption at the time of its generation. This result is used to calculate the real grid parity year - which lies somewhere between grid parity years calculated for wholesale electricity price and end user electricity price.     

中国太阳能光伏发电产业的现状与前景

光伏发电技术可直接将太阳光转换成电能,没有任何污染,有助于解决全球变暖的问题和我国的能源安全问题。文中介绍了光伏发电的市场和技术发展状况,叙述了太阳能电池、并网发电以及光伏一体化建筑技术,提出了“阳光三峡”的理念,展望了国内光伏发电的前景。     

Efficiency in the disinfection of water for human consumption in rural communities using solar radiation

The efficiency of solar disinfection for the inactivation of Total Coliforms (TC) and Escherichia coli (EC) in drinking water was tested in rural communities of the Guachochi Municipality, in the Tarahumara Sierra, State of Chihuahua, Mexico.The study zone was selected mostly because it lacks formal water supply systems and the population is forced to consume untreated water directly from rivers and shallow or artesian wells without treatment.To determine the bacteriological quality of the water consumed by the population, the amount of TC and EC in the water supplies of 23 communities in the studied municipality was determined.The efficiency of the solar energy based water disinfection process was determined for several months of the humid and dry seasons with water from the most contaminated sources of the study zone. The performed tests consisted in studying the effect of disinfecting water by direct exposure to sunlight during the whole day, with and without solar concentrators, in plastic bottles of commercial beverages. The three types of bottles used were transparent, partially painted black (one half of the bottle, along the longitudinal axis), and totally black.The study shows that, in this geographic zone, the available water must be disinfected before consumption and disinfection efficiency can reach 100% through the use of solar radiation. It was found that, since more than 6 h of daily solar radiation are available during most of the year in this zone, no solar concentrators are really necessary to ensure the complete elimination of bacteria. A complete disinfection takes place by simply placing water bottles in the sunlight during the whole day.Nevertheless, the use of solar concentrators and bottles partially painted black increases the TC and EC inactivation efficiency, reducing the solar exposure time required for a total disinfection to just 2 h. With the use of solar concentrators and partially blackened bottles, the water temperature reached 65 °C, while only 50 °C were achieved when using the same concentrators and completely transparent bottles.     

An investigation of mismatch losses in solar photovoltaic cell networks

Solar photovoltaic (PV) arrays in field conditions deliver lower power than the array rating. In this paper, the sensitivity of solar cell parameters in the variation of available power from the array is investigated. The parameters characteristic of aging and fresh cells used in prototype field systems have been used for computation of reduction in the available power. It is found that in series string the fractional power loss would increase from 2% to 12% with aging of solar cells. However, this fractional power loss may be reduced to 0.4–2.4% by an appropriate series-paralleling.     

Novel high efficient offline sensorless dual-axis solar tracker for using in photovoltaic systems and solar concentrators

In this study, a novel high accurate offline sensorless dual-axis solar tracker is proposed that can be widely used in photovoltaic systems and solar concentrators. The offline estimated data extracted from solar map equations are used by the tracker to find the sun direction where the maximum value of solar energy is captured. The solar tracker has been built, and it is experimentally verified that 19.1%–30.2% more solar energy can be captured depending on the seasons by utilizing the tracker. The contribution of this work is that the proposed offline sensorless dual-axis solar tracker not only has a very simple structure with a fabrication cost much less than sensor based solar trackers but also high accurately tracks the sun direction with a very small tracking error of only 0.43° which is less than the other sensorless and sensor based dual-axis solar trackers reported in the literature excluding the sensor based dual-axis solar trackers equipped with expensive sensors mounted on high accurate mechanical carriers. Furthermore, unlike all sensor based solar trackers, since the technique is offline, the proposed tracker does not use any feedback signal, and thus, its operation is independent from external disturbances and weather conditions such as cloudy sky.     

An evaluation of the installation of solar photovoltaic in residential houses in Malaysia: Past,present, and future

This paper examines solar energy development in Malaysia, particularly in relation to the installation of solar Photovoltaic (PV) in residential houses. It analyzes the past activities related to solar energy in Malaysia, in terms of research and developments (R&Ds), the implementations used as well as the national policies for the past 20 years which have pushed the installation of PV in the country. The Feed-In Tariff (FiT) scheme is discussed, showing comparative cost-benefit analysis between the PV installation in houses in the United Kingdom (UK) and Malaysia, and with other investment schemes available in Malaysia. To investigate the awareness of renewable energy policies and incentives, a preliminary survey of the public opinion in Malaysia has been carried out, and an evaluation of public willingness to invest in the FiT scheme by installing the PV on their houses is presented. The cost-benefit analysis shows that the proposed FiT programme is capable of generating good return on investment as compared to the one in the UK, but the return is lower than other investment tools. The survey suggests that most Malaysians are unaware of the government’s incentives and policies towards renewable energies, and are not willing to invest in the FiT scheme.     

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.     

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。     

Predicting the energy production by solar photovoltaic systems in cold-climate regions

One challenge in designing a photovoltaic (PV) system is to predict its generation, given parameters such as location, meteorological conditions, and layout. A greater challenge is to predict the generation of such a system under snow-cover condition. Publicly available snowfall data provide records for horizontal surfaces. However, the effect of snow accumulated on a tilted PV module remains unknown. Hence, irradiance is insufficient for predicting the output of PV systems having any given layout configuration. The research in this paper aims to predict the daily generation of PV systems through the development of a predictive model flexible enough to accommodate different layout configurations based on long-term monitoring data collected from 85 sites. Snow coverage loss factors are derived empirically to enhance the performance of the model. A feed-forward artificial neural network model is developed and implemented with snow adjustments (snowfall data and snow coverage loss factors). Promising results are obtained and validated.     

Technical and economical system comparison of photovoltaic and concentrating solar thermal power systems depending on annual global irradiation

Concentrating solar thermal power and photovoltaics are two major technologies for converting sunlight to electricity. Variations of the annual solar irradiation depending on the site influence their annual efficiency, specific output and electricity generation cost. Detailed technical and economical analyses performed with computer simulations point out differences of solar thermal parabolic trough power plants, non-tracked and two-axis-tracked PV systems. Therefore, 61 sites in Europe and North Africa covering a global annual irradiation range from 923 to 2438 kW h/m² a have been examined. Simulation results are usable irradiation by the systems, specific annual system output and levelled electricity cost. Cost assumptions are made for today's cost and expected cost in 10 years considering different progress ratios. This will lead to a cost reduction by 50% for PV systems and by 40% for solar thermal power plants. The simulation results show where are optimal regions for installing solar thermal trough and tracked PV systems in comparison to non-tracked PV. For low irradiation values the annual output of solar thermal systems is much lower than of PV systems. On the other hand, for high irradiations solar thermal systems provide the best-cost solution even when considering higher cost reduction factors for PV in the next decade. Electricity generation cost much below 10 Eurocents per kW h for solar thermal systems and about 12 Eurocents/kW h for PV can be expected in 10 years in North Africa.     

Experimental study on the effect of dust deposition on solar photovoltaic panels in desert environment

The accumulation of dust particles deteriorates the performance of solar cells and results in appreciable losses in the generated power due to the sun irradiance scattering effects on the surface of the solar panel. This study investigates the impact of dust accumulation on photovoltaic solar modules in Baghdad city in Iraq. For this purpose an experiment has been conducted to quantify losses caused by the accumulation of dust on the surface of three identical photovoltaic solar modules. The modules have been installed with direct exposure to weather conditions, in a well controlled experimental setup. Subsequently, measurements of dust accumulation on modules have been taken on daily, weekly and monthly basis. The dust density and size distribution of aerosol particles and fibers have been also investigated and measured by a highly sensitive aerosols measuring system. The dusted module and another similar clean module have been then exposed to constant radiation and constant temperature using a solar simulator as light source. The deposition of the dust on the surface of the photovoltaic solar modules showed a reduction in both the short circuit current (I_sc) and the output power compared to the same parameters of the clean module. The average degradation rate of the efficiencies of the solar modules exposed to dust are; 6.24%, 11.8% and 18.74% calculated for exposure periods of one day, one week and one month. The experimental results are well compared with the calculations obtained by a theoretical model recently developed by the authors.     

Demand analysis for solar photovoltaic cells—a case study of Gundlupet Taluk

The demand for energy in India has been growing steadily over the years. Since conventional energy options have failed to cope with this increase, there has been growing interest in non-conventional energy sources. Solar photovoltaic (SPV) cells could be one such alternative energy source since solar energy is available abundantly in India. It is also renewable and non-pollutant. In this paper, estimation of demand for SPV cells in a drought-prone area of Karnataka State, Gundlupet, is projected for four identified market segments for the year 1996. Comparison of the cost of generation by SPV with that of conventional hydroelectricity with present and future costs is also made. The demand projections are encouraging for use of SPV cells. The projected cost of SPV energy by AD 2000 for amorphous silicon cells would be Rs 7·01 per kilowatt hour for a module price of Rs 55 per peak watt of power and a distance from the rigid of 3 km.     

利用计算机模拟太阳能光伏发电

太阳能光伏发电是利用太阳能电池这种半导体电子器件有效地吸收太阳光辐射能,并使之转换成电能的直接发电方式。开发利用太阳能这种可再生的清洁能源发电是解决能源短缺、保护环境的重要途径。本文概述了太阳能光伏发电技术的研究情况,根据传热学及相关知识建立数学模型,并运用Lab VIEW软件对该系统进行动态模拟与仿真。     

Evaluation of the development potential of rooftop solar photovoltaic in Taiwan

Because of extensive exploitation, fossil fuels are gradually becoming depleted and global warming issues are increasing. Therefore, all nations must develop alternative energy resources to reduce the potential risk of exhausting the available fossil fuel energy supply and to resolve environmental degradation.The amount of sunlight and installed power capacity are crucial factors that influence solar photovoltaic (PV) efficiency. Among domestic and international studies, numerous scholars have proposed various installed power capacity assessment models, which typically calculate areas based on sub-fields, ground floors or per capita. However, an evaluation of the potential of solar PV power generation on rooftops indicated that the shadow effect caused by building structures substantially influence the amount of installed power capacity. This study aims to effectively compute the shadow areas (shaded areas) on rooftops. By using the Hillshade module, the buildings' elevation data and the solar azimuth and altitude angles at different hours were calculated to obtain the hourly sun/shade grayscale values. The grayscale values were then integrated into binary images to calculate the shadow areas on rooftops.This study suggests that the rooftop solar photovoltaic installation capacity is some 12,428.5 MW and power generation capacity 15,423.75 GWh in Taiwan.     

太阳能光热与光电/光热系统在中国不同建筑气候带下的性能研究

文章利用TRNSYS动态模拟软件研究了在我国不同建筑气候带条件下,不同类型的太阳能PV/T集热系统和普通太阳能PT集热系统的各项性能.其中,太阳能PV/T集热系统分为基于普通玻璃型太阳能PV/T集热系统和基于Low-e型太阳能PV/T集热系统.文章探究了基于普通玻璃型太阳能PV/T集热系统和基于Low-e型太阳能PV/...     

邯郸地区温度和灰尘对独立太阳能光伏发电系统的影响

通过具体的实验,研究邯郸市温度和灰尘对太阳能光伏发电系统的影响。利用红外测温仪测量太阳能光伏板温度,记录温度变化对输出电流、电压、功率的影响;对比光伏板在干净及积尘下系统输出电流、电压、功率的变化。结果表明:温度及灰尘对系统的影响较小。     

Theoretical analysis of the optimum energy band gap of semiconductors for fabrication of solar cells for applications in higher latitudes locations

In this work some results of theoretical analysis on the selection of optimum band gap semiconductor absorbers for application in either single or multijunction (up to five junctions) solar cells are presented. For calculations days have been taken characterized by various insolation and ambient temperature conditions defined in the draft of the IEC 61836 standard (Performance testing and energy rating of terrestrial photovoltaic modules) as a proposal of representative set of typical outdoor conditions that may influence performance of photovoltaic devices. Besides various irradiance and ambient temperature ranges, these days additionally differ significantly regarding spectral distribution of solar radiation incident onto horizontal surface. Taking these spectra into account optimum energy band gaps and maximum achievable efficiencies of single and multijunction solar cells made have been estimated. More detailed results of analysis performed for double junction cell are presented to show the effect of deviations in band gap values on the cell efficiency.