Yazar "Celik, Ali Naci" seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • Küçük Resim
    Öğe
    A critical review on the estimation of daily global solar radiation from sunshine duration
    (Pergamon-Elsevier Science Ltd, 2006) Yorukoglu, Mehmet; Celik, Ali Naci
    Models such as the Angstrom-Prescott equation are used to estimate global solar radiation from sunshine duration. In the literature, researchers investigate either the goodness of the model itself or the goodness of the estimation of global solar radiation based on a set of statistical parameters such as R-2, RMSE, MBE, MABE, MPE and MAPE. If the former is the objective, then the statistical analysis should naturally be based on H/H-o-S/S-o (the ratio of daily solar radiation to extraterrestrial daily solar radiation vs. the ratio of sunshine duration to day length). If the latter is investigated, then the statistical analysis should be based on H-c-H-m (calculated daily solar radiation vs. measured daily solar radiation). A literature survey undertaken in the present article showed that these two data sets are apt to be confused, drawing the statistical parameters to be used in assessment of the estimation model from the latter data set or the vice versa set. The statistical parameters are clearly derived from the basics for both of the data sets, and the inconsistencies caused by this confusion and other factors are exposed. A case study of the estimation models and global solar radiation estimation from sunshine duration is presented using five different models (linear, quadratic, cubic, logarithmic and exponential), which are the most common models used in the literature, based on 6 years long measured hourly global solar radiation data. (c) 2005 Elsevier Ltd. All rights reserved.
  • Küçük Resim
    Öğe
    Modelling and experimental verification of the operating current of mono-crystalline photovoltaic modules using four- and five-parameter models
    (Elsevier Sci Ltd, 2007) Celik, Ali Naci; Acikgoz, Nasir
    This article presents the modelling and experimental verification of the operating current of a 120 W of mono-crystalline photovoltaic module using four- and five-parameter analytical models. The southern part of Turkey, where the experimental system is mounted, is particularly well suited to photovoltaic installations. The operating current of the photovoltaic module, calculated from the models, is validated based on a series of experimental measurements. As well as the current and voltage of the photovoltaic module, the environmental variables such as ambient temperature and solar irradiance were measured and used for validation of the operating current. The photovoltaic cell models considered in this article are drawn from the equivalent electrical circuit that includes light-generated current, diode reverse saturation current, and series and shunt resistances. The simplified four-parameter model assumes the shunt resistance as infinite and thus neglects it. After determining the model parameters, the operating current is calculated using both models and compared to the measured current produced by the photovoltaic module. It is shown that the complete five-parameter model predicts the operating current better than the simplified four-parameter model, especially around solar noon, when most of the power is produced. (c) 2006 Elsevier Ltd. All rights reserved.
  • Küçük Resim
    Öğe
    Present status of photovoltaic energy in Turkey and life cycle techno-economic analysis of a grid-connected photovoltaic-house
    (Pergamon-Elsevier Science Ltd, 2006) Celik, Ali Naci
    The electricity consumption in Turkey increased on average 8.5% annually between 1990 and 2000, but decreased 1.2% in 2001 due to the economic crisis of 2000. The economic growth and electricity consumption are expected to continue in a similar rate of before the crisis in the coming years. Turkey is going through a change of policy in the energy sector, adopting a policy of privatisation. On the other hand, Turkey needs adaptations in the energy field for meeting the European standards as Turkey is seeking a full membership to the European Union. The alternative and renewable energy systems have been neglected so far in Turkey but must be included in the new energy programs. The renewable energy contribution in the total primary energy production is insignificant. The current installed photovoltaic capacity is in the level of a fraction of MW, which is tiny when compared to the solar energy potential in Turkey. In this article, a photovoltaic-house, which would have photovoltaic as the main energy source, is hypothetically designed to assess the techno-economic feasibility of grid-connected photovoltaic systems in Turkey. The grid electricity is used when the photovoltaic system fails to meet the required electricity. The performance of the photovoltaic system is simulated on an hourly basis to determine the autonomy level, using one year long hourly time-series solar radiation data of Ankara obtained from the Turkish State Meteorological Service. Then, some combinations of photovoltaics and grid electricity with different buy-back ratios are analysed. (c) 2004 Elsevier Ltd. All rights reserved.
  • Küçük Resim
    Öğe
    A review of installed solar photovoltaic and thermal collector capacities in relation to solar potential for the EU-15
    (Pergamon-Elsevier Science Ltd, 2009) Celik, Ali Naci; Muneer, Tariq; Clarke, Peter
    This article analyses the energy statistics of 15 European Union countries (EU-15), giving special emphasis to the installed solar photovoltaic and thermal collector capacity. The installed capacities per capita are analysed in relation to the solar radiation income of respective countries with the view to explore the relationship between the solar income and its utilisation as of the year 2006. In terms of the installed solar thermal collector capacity, Austria leads the statistics amongst the countries studied with 223W(th) collector capacity per capita, followed by Greece with 207W(th). Except for Greece, it is observed that the countries with high solar radiation income are lacking to realise their solar potential. Regarding the installed photovoltaic power per capita, Luxembourg leads the pack by a wide margin with 47W(p) capacity, followed by Germany with 30W(p). Fiscal instruments to invigorate the deployment of solar energy have also been identified in this work. (C) 2008 Elsevier Ltd. All rights reserved.
  • Küçük Resim
    Öğe
    A techno-economic analysis of wind energy in southern turkey
    (Taylor & Francis Inc, 2007) Celik, Ali Naci
    Turkey's total primary energy production covered 33% of the total energy consumption in 2005. It is predicted that this ratio of 33% will decrease further in the coming years. Therefore, Turkey has to make better use of her renewable energy resources, such as wind and solar. Studies show that Iskenderun (36.35 degrees N, 36.10 degrees E), located on the Mediterranean coast of Turkey, is amongst the possible wind energy generation regions. In the present study, the wind energy potential of the region is statistically analysed based on five year hourly time-series wind-speed data at two different wind-turbine heights. Economically usable power generation is hypothetically analysed for various wind turbines employing a typical year, using a model of quadratic power output function. A life-cycle cost analysis is carried out over a 20-year system lifetime. The wind turbine generators considered are of various nominal powers ranging from 0.6 to 500 W. It was shown that the wind turbine with the nominal power of 500 kWprovided the lowest cost of electricity at $0.15 per kWh. This is very close to $0.13, which is the cost of electricity per kWhfrom the utility in Turkey. The cost of wind electricity per kWh can be significantly reduced if the components of wind energy systems were exemptedfrom taxes and subsidies were introduced.