Generation of a typical meteorological year using sunshine duration data
Introduction
Accurate prediction of the long-term performance of solar systems, such as photovoltaic applications, active and passive heating and cooling, depends on the long-term climatic features at a location. The need for one-year performance calculation of such systems led to the development of a Typical Meteorological Year (TMY) [1], [2], [3] or Test Reference Year (TRY) [4], [5], [6], [7] or Design Reference Year (DRY) [8].
At present there are several methods for the generation of a TMY. In chronological order, they are:
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Danish method by Anderson et al. [8] in 1977 and by Lund and Eidorff [5] in 1981;
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Sandia National Laboratory method (TMY) presented by Hall et al. [1] in 1978;
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Festa Ratto method [9] in 1993;
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TMY2, which is a modification of the original Sandia method by Marion and Urban [10] in 1995.
A study has been carried out [11] for the generation of a TRY using the meteorological data of Turkey as the first effort. In this work [11], the global radiation data were estimated by a model described in Ref. [12], using daily sunshine duration data.
In this paper the TMY2 method is applied due to its large acceptance in USA and Canada where the method is applied to 239 stations. TMY2 method utilizes nine daily parameters; the eight of these daily parameters used for the selection of the typical months consist of the maximum, minimum, and mean dry-bulb air temperature, the maximum, minimum, and mean relative humidity, the maximum and mean wind velocity. The ninth parameter used in the analysis is daily global solar radiation. In this paper, one of the following four variables was examined to be the ninth parameter in the procedure: the daily global solar radiation, the measured daily bright sunshine duration, the daily bright sunshine duration over day-length, and the ratio of daily global to extraterrestrial daily global solar radiation. The reason for such a test is the abundant sunshine recording stations (70) in Turkey compared to the few stations recording solar radiation data using accurate instruments.
Section snippets
Description of the methods
The Danish method [5], [8], which will not be presented in detail here, uses a three-step procedure for the selection of the months that will be considered in the TRY. The method uses daily meteorological data such as the average temperature, maximum temperature, relative humidity, wind speed, atmospheric pressure, sunshine duration, and global solar radiation in one of the steps, whereas daily average temperature, daily maximum temperature, daily global radiation, and daily sunshine duration
TMY2s for Ankara
Eight daily parameters used for the selection of the typical months consist of the maximum, minimum, and mean dry-bulb air temperature, the maximum, minimum, and mean relative humidity, the maximum and mean wind velocity. As for the ninth parameter, daily global solar radiation (H) or daily sunshine duration (s) is used. The relation between the ratio of the measured sunshine duration to the day-length (s/S) and the ratio of daily global solar radiation to extraterrestrial daily solar radiation
Data used in the analysis
The data of Ankara covering the period 1979–1999 was obtained from the Turkish State Meteorological Service (TSMS). The candidate months of TMY2 were determined using the daily data obtained from hourly values. The missing data, accounting for 1% of the whole database, were completed by taking the arithmetic mean of the values of previous and next days. The radiation data were taken from Robitzch-type actinographs, the dry-bulb temperature from thermometers, the relative humidity from
Results and discussion
We should point out that although the accuracy of Robitzch-type actinography data is 20% there still exists a correlation between the daily sunshine duration and daily global solar radiation data taken by this instrument. The reason for such a correlation is because of the effective role of systematic errors in the overall accuracy of the Robitzch actinographs.
A statistical analysis is done to see how closely does s represent H as the ninth parameter in obtaining TMY2s. The variables considered
Conclusion
The possibility of using the daily sunshine duration or the ratio of the daily sunshine duration to the day-length instead of daily global solar radiation, as the ninth parameter, in the generation of the TMY is analyzed. The analysis aims at locations with abundant data of daily sunshine duration where long-term data of daily global solar radiation is lacking. However, due to the unreliable solar radiation data recorded by Robitzch-type heliographs, the accuracy in obtaining the TMY is not as
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2015, International Journal of Hydrogen EnergyCitation Excerpt :In this sense, in the past several empirical formulas using various parameters have been tested in order to estimate the solar radiation all over the world. In this regard, the studies conducted on the evaluation of solar radiation measurements in Turkey may be classified in 4 groups as follows [20]: (1) developing empirical correlations for Turkey in general [21–24] (2) developing empirical correlations for some provinces of Turkey such as Istanbul, Gebze, Trabzon, Antalya, Izmir, Konya [19,25–28] (3) data use for estimating solar radiation and indicating the results graphically [29–31] and (4) other solar radiation studies such as estimation and statistical analysis of Angström equation coefficients, estimation of solar irradiation, determination of Turkey's monthly clearness index values and estimation of solar energy gain. In this study, solar radiation models on the horizontal surface have been investigated to establish solar photovoltaic (PV) system for solar-hydrogen hybrid energy generation and by making use of the data gathered from the meteorological measurement device (vantage PRO2) installed in the university campus of Osmaniye Korkut Ata.