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The largest output fluctuation is an index used to quantify the disturbance of a power grid caused by wind power plants and photovoltaic power generation systems connected to it. In order to develop its estimation method, we investigate the relationship between the largest output fluctuation and the standard deviation of a newly proposed random variable generated by differencing the output variation of photovoltaic power generation systems. Output fluctuation coefficients are defined and estimated using measured data of photovoltaic power generation systems located at 52 places. An approximation equation is presented to predict geographical correlations between the proposed random variables for photovoltaic power systems by using the distances between their locations. Finally, it is shown that the largest output fluctuation of many photovoltaic power generation systems dispersed in a wide area is predictable by using the output fluctuation coefficients and the equation approximating the geographical correlations of output fluctuations. ©2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 9–19, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20723

The largest output fluctuation is an index used to quantify disturbance against a power grid caused by wind power plants and photovoltaic power generation systems connected to it. To develop its estimation method, we investigate the relationship between the largest output fluctuation and the standard deviation of a newly proposed stochastic variable derived from the output variation of photovoltaic power generation systems. Output fluctuation coefficients are defined and estimated using the measured data of photovoltaic power generation systems located at 52 places. An approximation formula is presented to predict correlation factors between the stochastic variables corresponding to photovoltaic power generation systems using distances between their locations. Finally it is shown that the largest output fluctuation of many photovoltaic power generation systems dispersed in a wide area is predictable by using the output fluctuation coefficients and the formula to approximate the correlation factors.

Short-time fluctuations in solar irradiance will become an important issue with regard to future embedded photovoltaic (PV) systems. However, when PV systems are intensively installed, fluctuation of total output in clustered PV systems is not remarkable because there is the smoothing effect of irradiance in certain areas. In this paper, a new estimation method of irradiance fluctuation, which is based on the combination of the Fourier transform and the wavelet transform methods, is described.

Here, we present the results of evaluation of solar energy potential and photovoltaic (PV) module performance from actual data measured over a period of more than 2 years in the Gobi Desert of Mongolia. To allow estimation of solar energy potentials and durability of PV systems in the Gobi Desert area, a data acquisition system, including crystalline silicon (c-Si), polycrystalline silicon (p-Si) modules, and two sets of precision pyranometers, thermometers, and anemometer, was installed at Sainshand City in October 2002. This system measures 23 parameters, including solar irradiation and meteorological parameters, every 10 min. High output gain was observed due to operation at extremely low ambient temperatures and the module performance ratios (PRs) were high (>1·0) in winter. In summary, the present study showed that a PV module with a high temperature coefficient, such as crystalline silicon, is advantageous for use in the Gobi Desert area. Copyright © 2006 John Wiley & Sons, Ltd.

モンゴル国では, 遊牧民の生活水準の向上を目的として住居 (ゲル) を電化するために1999年から独立小型太陽光発電システム (SHS) が導入されている. 本研究では, ヒアリング調査 (67世帯) とアンケート調査 (359票) によりSHS利用者の利用実態と未利用者の認識を明らかにし, 今後のSHSの普及定着に向けての課題について検討した. 主な知見として, 以下の5つが得られた.(1) SHSの導入によって照明とテレビの使用が可能になったことに対して, SHS利用者は高い満足感を得ていた. また, SHSは小型かつ軽量であり, 燃料を必要としないため, 他の電源と比較して, 移動を繰り返す遊牧民のライフスタイルに適合する技術であることが示された. (2) SHSを導入した世帯の78%が「10万ソーラーゲル計画」による補助金と無利子ローンを活用しており, 市場を通しての普及が進んでいない. (3) SHSの課題は, SHSの保証期間が1年以内と短いこと, 修理店または技術者が近くの村落センターまたは県都にいないことなどである. (4) 未利用者のSHSに対する認識度が高く, SHSを購入予定があるという回答者が多いことが分かった. (5) SHSの普及定着及びそれによる遊牧民の農牧業の生産性向上のための課題は, 市場原理に向けた優遇措置の見直し, サポート体制の整備, 農牧業情報の活用環境の整備である.

Under the auspices of the New Sunshine Program and continuous RD 975 h in 2000, 982 h in 2001 and 975 h in 2002, and the mean value of the performance ratio was over 70%; 73·3% in 2000, 71·8% in 2001 and 72·5% in 2001. Copyright © 2004 John Wiley & Sons, Ltd.

To propose a formula for calculating in-plane irradiation onto a tilt surface from measured data on the tilt angle, detailed examination has been made by using data obtained for every 1 min. A new model to estimate in-plane irradiation from horizontal irradiance has been developed. Especially, it is showed that new model can estimate scattered irradiance correctly rather than the existing model by using scattered component ratio and clearness index . It is considered that measuring 1-min data has favorable influences instead of hourly data. Fluctuation of 1-min data contributes to estimate the scattered component.

Data evaluation methods have wide adaptations, such as feedbacks to PV system operation management and design. The authors have already developed sophisticated verification method (SV method) of PV systems, which is a simple evaluation method to identify six kinds of system loss rates using basic information and simple four measurable data. This time, the authors introduced quality diagnosis to our previous model for compensating the measurement errors in field data, and improved the algorithm of the model. Consequently, validity of the evaluation result became better than the previous model.

To develop a new formula for calculating irradiation onto an arbitrary orientation–inclination plane, detailed examinations have been made by using data obtained at every 1 min interval with four types of pyranometer, such as horizontal, diffuse, direct normal, and tilt global. Instantaneous irradiance values sampled with 1 min interval have been verified by clearness index, which is a parameter independent of the lapse of time. Scattered tendencies observed on direct and diffused component ratios have been studied in detail by classifying data into different classes of clearness indices. In our model, moving averages of time-series irradiance data provide the information of weather condition in order to select model parameters prepared for assumed three types of clouds conditions. Only global irradiance data monitored at 1 min intervals are used for the input of the model. The result of this work demonstrates that an algorithm associated with the Perez model can estimate the in-plane irradiation with a RMSE of about 50 W/m 2 .

This paper describes the methods for forecasting solar irradiance by using geostationary meteorological satellite (GMS) images. As the first attempt the authors forecasted the cloud albedo for a basic study of irradiance estimation by estimating the driving drift vector of clouds using GMS images. A new procedure is also proposed for removing the effect of ground albedo, which disturbs cloud movement analysis. This time, annual forecastable probability was estimated as 81.3% for 1 h ahead, 71.0% for 2 h ahead and 59.3% for 3 h ahead.

The authors have developed the sophisticated verification (SV) method, which can evaluate involving performance ratio, power conditioner efficiency, temperature factor, shading factor, load matching factor and other array parameter. So, we also have ensured adequacies of the evaluation of PV systems. However, the originally proposed method accepts PV installations facing the south only. In this paper, we have modified the SV method by taking into account the arbitrary orientation and inclination, because of improved the accuracy of evaluation. Therefore, the shading effect can be intelligible for each hour. The maximum value of shading losses reached 13.1%.

This paper describes the method for forecasting the cloud albedo as a basis study to estimate the irradiation by using geostationary meteorological satellite (GMS) images. A new procedure is also proposed to remove the effect of ground albedo, which disturbs the cloud movement analysis. The validity of the method for forecasting the cloud albedo was examined. The forecast probability was estimated as yearly 66.8% for one hour ahead, 58.5% for two hours ahead and 52.7% for three hours ahead at 20 sites in Japan. Results over 80% for one hour ahead at Sapporo were obtained. It seems reasonable to suppose that this method can be used only for a specific site and season.

This paper describes the methodology for quantification of solar irradiance fluctuation in order to analyze the areally totalized PV systems, which consist of a large number of PV systems connected to each other in the optimum size of a certain community area. Two factors quantifying the fluctuation, fluctuation factor and power spectral density, and some examples are presented. Also cross-correlation analysis between nine stations' measurements were operated to estimate the extent of the power fluctuation in a certain area size and to determine optimum size of the area of areally localized PV systems.

The purpose of this study is to investigate CPV system performance in different climate conditions. The system data has been collecting since 2011. The same manufacturer's CPV systems have been operating in Aurora, CO, U.S. and Okayama, Japan. The relationship between the CPV performance and environment is considered from two different climate data sets. According to the energy yield analysis, the CPV array at the U.S. site generates more than twice the energy compared with Japan. The CPV array yield is better than the Fixed PV in U.S. site. In reverse, the Fixed PV is better than the CPV in Japan. The performance ratio (PR) of the CPV clearly decreases in winter while the conventional fixed flat PV increases at both sites. Based on spectral and temperature effects analysis, we conclude that the spectrum has a strong negative effect on the performance in winter. The spectral loss was up to 11.0% of its performance. The other factors: cf. soiling, alignment, tracker error, etc., had about 5% effect regardless of season. It was confirmed that these factors are non-negligible.

Performance of III-V multi-junction solar cells depends on spectral conditions according to which junction limits the photocurrent. Specifically, the response of concentrating multi-junction solar cells depends on the illumination at the cell surface. Because the illumination condition depends on alignment, it is important to characterize the CPV performance not only for a mono-module but also for a system or an array. In this paper the spectral effect on the CPV system and the mono-module consisting of III-V multi-junction solar cells from three different manufactures will be discussed.

Recently, the utilization of cloud images obtained by Geostationary Meteorological Satellite (GMS) has been proposed by several organizations for solar irradiation monitoring [1,2]. In order to exactly estimate the irradiation at ground-level by the images, it must be noted that the images are affected by seasonal and local variations, especially caused by ground albedo. Nowadays, the computations of the albedo are performed by using a time series of the images. Example maps of the albedo are also given for each season. In addition, a new rule of estimating the irradiation by using the albedo is proposed. Using this new method, the annual- and seasonal-integrated global irradiation can be estimated with good accuracy in spite of ground conditions.

Cultured Glycyrrhiza echinata L. (Leguminosae) cells produce a retrochalcone echinatin (4,4[prime]-dihydroxy-2-methoxychalcone) and its biosynthetic intermediate licodione [1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)-1,3-propanedione, a dibenzoylmethane (keto form) or its enol tautomer ([beta]-hydroxychalcone)], when treated with elicitor-active substances, e.g. yeast extract. A microsomal fraction (160,000g pellet) prepared from yeast extract-induced suspension cultures of G. echinata catalyzed the formation of licodione from (2S)-liquiritigenin (7,4[prime]-dihydroxyflavanone) in the presence of NADPH and air. This licodione synthase activity was shown to be dependent on cytochrome P450 by its microsomal localization, requirement of NAD(P)H and O2 for activity, and inhibition by typical cytochrome P450 inhibitors. Licodione synthase activity transiently increased in the cells after treatment with yeast extract. When (2S)-naringenin (5,7,4[prime]-trihydroxyflavanone) and NADPH were incubated with the same microsomal preparation, a polar compound, which further converted into apigenin (5,7,4[prime]-trihydroxyflavone) when treated with acid, was produced. The reaction mechanism of licodione synthase is likely to be 2-hydroxylation of the flavanone molecule and subsequent hemiacetal opening and is possibly the same as the previously suggested mechanism of flavone synthase II from soybean and, furthermore, closely related to isoflavone synthase from Pueraria lobata.

The performance of photovoltaic modules is influenced by solar spectrum even under the same solar irradiance conditions. Spectral factor (SF) is a useful index indicating the ratio of available solar irradiance between actual solar spectrums and the standard AM1·5-G spectrum. In this study, the influence of solar spectrum on photovoltaic performance in cloudy weather as well as in fine weather is quantitatively evaluated as the reciprocal of SF (SF−1). In the cases of fine weather, the SF−1 suggests that solar spectrum has little influence (within a few %) on the performance of pc-Si, a-Si:H/sc-Si, and copper indium gallium (di)selenide modules, because of the “offset effect”. The performance of a-Si:H modules and the top layers of a-Si:H/µc-Si:H modules can vary by more than ± 10% under the extreme conditions in Japan. The seasonal and locational variations in the SF−1 of the bottom layers are about ± several %. A negative correlation is shown between the top and bottom layers, indicating that the performance of a-Si:H/µc-Si:H modules does not exceed the performance, at which the currents of the top and bottom layers are balanced, by the influence of solar spectrum. In the cases of cloudy weather, the SF−1 of the pc-Si, a-Si:H/sc-Si, and copper indium gallium (di)selenide modules is generally higher, suggesting favorable for performance than that in fine weather. Much higher SF−1 than that in fine weather is shown by the a-Si:H module and the top layer of the a-Si:H/µc-Si:H module. The SF−1 of the bottom layer neither simply depend on season nor on location. Copyright © 2011 John Wiley & Sons, Ltd.

PV customers wish to have confidence in PV modules they purchase. Today, no test can quantify a module’s lifetime with confidence, but stress tests are routinely used to differentiate PV product designs. We suggest that the industry would be strengthened by using the wisdom of the community to develop a single set of tests that will help customers quantify confidence in PV products. This paper evaluates the need for quality assurance (QA) standards and suggests a path for creating these. Two types of standards are needed: 1) QA of the module design and 2) QA of the manufacturing process., JRC.F.7-Renewable Energy

This paper presents the results of a long-term performance analysis of PV-hybrid system based on 5 years operational data from the field site of Noyon soum, Umnugobi province, Mongolia, project supported by New Energy and Industrial Technology Development Organization of Japan (NEDO). The NEDO has performed demonstrative research on the independent dispersed PV-hybrid systems: PV, 200kW, DEG (Diesel Engine Generator): 100kVA*3set) from 2002 to 2004 in Mongolia. The main purpose of this project was to improve system reliability and cost performance on the natural conditions and distinctive social systems, which are rarely seen in Japan. It has been observed that the high PV penetration (during project period: 80.4% during 09/2003–12/2007) 71% of total supplied energy, and the low system failure ratio. On the other hand, average PR (performance ratio) indicated 0.20 (during project period), 0.14 (estimated values between 09/2003–12/2007) due to the limited demand and distributed/grid-connected PV units (100kW) with the auxiliary power mode.

This paper presents the evaluation results of a long-term performance of 2 type PV module from actual data measured over a period of more than 6 years in the Gobi Desert of Mongolia. For the purpose of estimating solar energy potentials and durability of PV systems in the Gobi desert area, a data acquisition system, which includes crystalline silicon (c-Si), polycrystalline silicon (p-Si) modules and precision pyranometer, thermometer and anemometer, have been installed at the Sainshand city in October, 2002. This system has been measuring 23 parameters including solar irradiation and meteorological parameters in every 10 minutes. It has been observed that the high output gain due to the operating condition in an extreme low ambient temperature and the PV module degradation rate indicated over −1.5[%/yr] after 6 years exposure test.

The authors set up an outdoor measurement system in Bangkok, Thailand for taking I–V characteristics of thirty PV modules (from ten manufactures) with meteorological data including solar spectrum irradiance in January 2006, and also set up a similar system in Gobi desert in Mongolia in 2002 and 2005. The change in spectrum irradiance mainly caused by the seasonal change in humidity affected the seasonal performance of a-Si considerably, though the effect of temperature change on the seasonal performance was relatively slight. Indices for characterizing solar spectrum and module temperature for energy ratings were introduced, and a simple regression model for predicting daily energy output of PV modules was verified.

PV is expected as a major carbon-free primary energy source which is inevitable to proceed to a carbon-free economy. However, as a variable power source, the large PV's penetration into the power system may cause various kinds of power system operation issues and/or expansion needs. In order to technically-and economically-feasible solution for these issues and needs, it is quite important to quantitatively analyze and evaluate the variation of PV generation. This paper will present the smoothing effect of the total PV generation output in a broad area by means of the maximum output fluctuation as fluctuation index.

In order to clarify factors affecting the timing of marriage and pregnancy of Japanese women, this paper examines the timing of marriage, the age at which women first met the men they eventually married, the time that elapsed between first meeting and engagement, between engagement and marriage, and between engagement and first conception for the 1937–1955 birth cohorts. Women resorting to an arranged marriage showed a large increase in the age at first meeting as well as marriage age, while women marrying on a love-match basis did not. Supporting the hypothesis that there are three stages of Japanese women's attitude towards marriage, which affect the pattern of time schedule to marriage, it is found that women with a larger probability of career-seeking are likely to have a higher age at first meeting and a longer time between engagement and marriage even in love-match cases. This study suggests that a large proportion of women preferred their marriage to be a love match, but only a minority were career...

The AIST 1 MW PV facilities consist of a total of 211 inverters of the 4-kW type designed principally for residential uses, and tens of inverters of the 10-kW unit designed principally for industrial uses. These inverters are connected to low-voltage (200 V) distribution line in AIST. There are 13 kinds of PV modules from 5 different technologies and tens kind of PV inverter from several manufactures. Benchmarking these PV components reveals the differences of the performance and reliability among other PV components under actual conditions. During the first two years, there were several failures in the system components, mainly caused by improper installation works. But the PV facilities showed proper performance ratio (around 70%) and perfect availability in total. The mean time of failure was 7.9 times. More than 64% of individual PV systems had no failures. The mean time to repair was only 3.3 days

The diagnosis and monitoring of PV systems are important to minimize the outage period and maximize the lifetime output. The objective of this research is to develop the failure detection technologies for PV systems which can be integrated into the power conditioners. There are some failure detection methods such as thermal methods, visual methods, and electrical methods. Between these methods, the electrical methods seem to be the most appropriate to integrate into the power conditioners. To determine the position of the failed module in PV array, the time domain reflectometry (TDR) is the most promising in electrical failure detection methods. In TDR method, the inputted signal into PV cell / module / string and the reflected signal from the circuit are compared. The signal delay and the change of waveform shape are translated into the failure position in the line and the type of failure. In our fundamental experiments under the dark conditions, the line length of several cells string and the line length of a module in which many cells are connected in series could be detected by TDR. These results show the possibility that TDR can find the electrical property changes of PV modules and can be used for failure detection method. Based on these fundamental experiments, the detailed diagnosis methods should be studied in more depth for their realization into power conditioners or test equipments.

The rapid growth and expansion of grid-connected photovoltaic (PV) systems utilization is significantly beneficial to the mitigation of environmental issues. Even though they are known as the maintenance free generation, PV systems have to be monitored and evaluated their output energy since certain troubles have been reported. Therefore, an evaluation method for PV systems seems to be necessary. In our laboratory with TUAT, the sophisticated verification (SV) method, which is the evaluation method for PV systems, has been developed. The method can estimate system losses by using a few utilized monitoring data items despite of numerous kinds of losses. The paper describes to summarize the SV method, and examples of evaluation results.

In our laboratory, the sophisticated verification method, which is the evaluation method for PV systems, has been developed. The accuracy of evaluation shading effect by using the SV method was not described because it is difficult to measure the shading effects. The procedure of estimation method is base on certain assumption. Therefore, in this paper, the accuracy of evaluation shading effect was indicated in the way to evince the adequacy of assumptions. As a result, depends of location and the data set up was indicated.

Photovoltaic (PV) system performance evaluations are required at the system deliveries to users. For the performance evaluations, it is very important to estimate the irradiance on the modules of PV system to design energy system or to check the energy output on-site. In this paper, we propose the estimation system of in-plane irradiance by regression functions from measured irradiance data. The system consists of the monthly regression functions R(t) of the minutely ratio of in-plane and global irradiance separated by clearness ratio. The data in three years for 100 residential PV sites in Japan were used to calculate and analyze the regression coefficients of these sites.

Solar energy maps that indicate the wide-ranging spatial distribution of solar irradiation are required by the researchers of the solar power systems. However, the irradiation measurement networks at ground level are not enough to obtain reliable information of the solar energy distribution in the world. On the other hand, geostationary meteorological satellites (GMS) have provided the images of cloud fields over the whole surface of the Earth. The main cause of an irregular change in the irradiation at the ground level is effect of the clouds; therefore, methods for estimating the irradiation by using the GMS images may be very useful. The solar irradiation for 14 sites in Japan was estimated by a semi-physical model developed by the authors. The RMS errors, averaged over 14 stations, were 0.0804 kWh/m/sup 2/ for hourly estimates, 0.534 kWh/m/sup 2/ for daily estimates and 7.14 kWh/m/sup 2/ for monthly estimates. There were little regional differences of estimate accuracy. An example of solar energy maps for Eastern Asia in 1992 is presented.

It is difficult to estimate precisely total irradiance on photovoltaic (PV) arrays without consideration of the effect of shadow by surroundings, especially for building integrated photovoltaic (BIPV) systems in an urban area. The accurate evaluation of actual irradiation on the arrays may contribute to the verification of the performance of PV systems. In this research, the authors propose the method of calculating the shading factor by applying the photo survey method using fisheye photographs to capture whole surroundings. The shading factor is defined as the ratio of actual irradiation on PV arrays to ideal irradiation with no shading modules. Actual irradiation on a certain array can be calculated easily by using the shading factor.

Statement of problem. A durable repairing system for denture base fracture is desired to avoid recurrent fracture. Purpose. This study evaluated the strength and modulus of elasticity of repaired acrylic specimens reinforced with various processes. Material and methods. Transverse strength and modulus of elasticity of repaired acrylic denture base specimens were evaluated with a 3-point bending test and compared with a heat-polymerized control. Autopolymerizing acrylic resin was used with woven metal fiber and glass fiber with and without methylene chloride surface treatment (n = 6 per group). The specimens were cut in half and fixed in a metal mold to obtain a space for placing the repairing resin. A cavity was prepared when metal or glass fiber was used. All specimens were stored in 37°C distilled water for 48 hours before the test. All data were statistically analyzed with 1-way ANOVA, and differences among groups were analyzed with Fisher test ( P ≤.05). Results. The mean value of the transverse strength for the control was 87.2 MPa. The specimens repaired by glass fiber with methylene chloride surface treatment exhibited the highest transverse strength (96.8 MPa), which was significantly higher than that of the control ( P ≤.05). The elastic modulus of the specimens repaired by glass fiber with methylene chloride surface treatment (4189.3 MPa) was significantly greater than that of the control (2683.7 MPa) at a 95% level of confidence. The values of transverse strength and elastic modulus were highest when the surface treatment was combined with a reinforcing glass fiber. Conclusion. Reinforcement with glass fiber and methylene chloride pretreatment produced transverse strength and a modulus of elasticity higher than the control. (J Prosthet Dent 2001;85:496-500.)

Various photovoltaic (PV) technologies are commercially available today. The effect of solar spectrum on the performance of PV modules should be evaluated quantitatively in order to estimate the module performance with high accuracy and precision. Average photon energy (APE) has been frequently applied to evaluate the effect of solar spectrum. The purpose of this study is to enhance the precision and accuracy by introducing other indexes. In this study, we select solar spectra, the integrated spectral irradiance (ISI) and APE of which are equivalent to those of the standard AM1.5G spectrum. There is a slight difference in shape, although the shapes are approximately similar. We introduce one more index, which defines the spectral irradiance at the atmospheric window or the depth of the water absorption band. The introduction would further improve the accuracy and precision of the evaluation of the effect of solar spectrum.