International Journal of Energy Studies
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INTERNATIONAL JOURNAL OF ENERGY STUDIES e-ISSN: 2717-7513 (ONLINE); homepage: https://dergipark.org.tr/en/pub/ijes Received: 08 Sep 2020 Research Article Revised: 22 Sep 2020 Int J Energy Studies, 2020;5(2):89-105 Accepted: 24 Sep 2020 Finding Optimum Tilt Angles of Photovoltaic Panels: Kütahya Case Study Oğuz Ozan Yolcana,*, Ramazan Köseb aKütahya Dumlupınar University, Faculty of Engineering, Mechanical Engineering Department ORCID: 0000-0002-6664-5675 bKütahya Dumlupınar University, Faculty of Engineering, Mechanical Engineering Department ORCID : 0000-0001-6041-6591 (*Corresponding Author: [email protected] ) Highlights For Kütahya, optimum tilt angles of photovoltaic panels were calculated For Kütahya, optimum tilt angles were obtained on a monthly basis Monthly average daily radiation amount coming to the optimum tilted plane were calculated You can cite this article as: Yolcan, O. O., Köse, R. “Finding optimum tilt angles of photoltaic panels: Kütahya case study”, International Journal of Energy Studies 2020;5(2):89-105 ABSTRACT It is important to make the most efficient use of solar energy, which is a renewable energy resource whose importance and use is increasing day by day. Due to the movement of the earth around its axis and around the sun, the angles of the sun rays reaching the earth are constantly changing. In order to make maximum use of the sun's rays, it is necessary to place the solar energy systems at the right angle. In this study, optimum tilt angles of the districts of Kütahya province were found for solar energy systems. Meteorological data and latitude information were used in the calculations, the amount of radiation coming to the horizontal plane, the amount of diffuse radiation, the amount of radiation coming to the horizontal plane outside the atmosphere and the amount of radiation coming to the optimum tilted plane were determined. Keywords: Solar energy, Photovoltaic panel, Optimum tilt angle 89 Int J Energy Studies 2020;5(2):89-105 1. INTRODUCTION The importance of renewable energy sources is increasing day by day at national and global level. The limited reserves of fossil-based fuels and their environmentally polluting properties make the use of renewable energy valuable at the global level, and our country's dependence on foreign energy at the national level. As can be seen in the world solar energy atlas given in Figure 1, our country has a high potential in terms of solar energy due to its location [1]. Figure 1. World solar energy atlas [1] In our country, the installed power of solar energy and consequently the generation of electricity from solar energy is increasing day by day. As of February 2020, the installed capacity of licensed solar energy in our country has been 174.75 MW, and the installed capacity of unlicensed solar energy has been 5,883.41 MW [2]. Electricity production from solar energy in February 2020; 18,861.9 MWh with license and 556,037.06 MWh without license [2]. Due to the movement of the earth around its axis and around the sun, the angle of incidence of sun rays constantly changes throughout the day and year. In order to benefit more from solar energy, photovoltaic panels with solar tracking mechanism are installed, the tilt angles of the fixed panels can be changed seasonally or the panel is placed at the angle where the solar energy can produce the most. There are studies in the literature about the optimum tilt angles of solar panels. 90 Int J Energy Studies 2020;5(2):89-105 Bakırcı has calculated optimum tilt angles for Adana, Ankara, Diyarbakır, Erzurum, İstanbul, İzmir, Samsun and Trabzon provinces and developed correlations for Turkey’ s cities optimum tilt angles [3]. Handoyo et al. calculated the optimum tilt angle for solar collectors in Surabaya region of Indonesia. The results obtained were compared with other studies in the literature [4]. Kallioğlu et al. calculated the 12-month optimum tilt angles for Gaziantep province. Optimum tilt angles varies between 0o and 57o on a yearly basis [5]. Koçer et al. calculated the 12-month optimum tilt angles of solar collectors for Ankara province and its districts. It has been stated that when the tilts angles are changed twice a year, there will be an increase of 5% compared to fixed collectors and an 8% increase in efficiency compared to fixed collectors when the tilt angles are changed every month [6]. Zang et al. calculated the 12-month optimum tilt angles for the Chinese cities located in 6 different climatic zones [7]. Şadanoğlu has calculated the optimum angles for solar energy systems by making measurements in March, April, May and June for Eskişehir province [8]. Ajder calculated the optimum tilt angle for the city of Boston, USA using meteorological data. In the calculations for the range of 0o-90o, the optimum tilt angle was obtained as 49o [9]. Calabro has developed an algorithm for calculating the optimum tilt angles of photovoltaic panels using solar radiation data from various meteorological stations [10]. Ayaz has modeled different types of photovoltaic modules using meteorological data and calculated the optimum tilt angles for these modules under Istanbul conditions [11]. Yılmaz calculated optimum tilt angles of all provinces of Turkey. In addition, various correlations have been developed to calculate the optimum tilt angle. [12]. Eren, using Visual C # language, has created an interface that calculates the optimum tilt angle. The optimum tilt angle calculated and evaluated for Turkey and Ankara [13]. Eker calculated the optimum tilt angle for the panel for the province of Bursa, and also examined the effect of the cooling effect of the wind on the panels [14]. There are studies on this subject in the literatüre [15-22]. 2. MATERIAL In this study, optimum tilt angles for 12 months of the year were calculated for the province of Kütahya and its districts. Kütahya is a city located in the Aegean Region of our country, with a surface area of 11,634 km2, consisting of 13 districts including its central district. The location of the province is between the 28.59-30.50 eastern meridians and 38.82-39.89 northern parallels. The solar energy potential map of Kütahya province, including the district boundaries, is shown in Figure 2 [21]. As can be seen 91 Int J Energy Studies 2020;5(2):89-105 from the figure, Kütahya province has a high solar energy potential. For the district centers of the province of Kütahya; General information including latitude, longitude, altitude, average daily solar radiation, average daily sunshine duration and annual average temperature are shared in Table 1 [23-25]. In the north of Kütahya, the annual average solar radiation values are 1450-1500 kWh/m2, while in the southern regions of Kütahya this value reaches the levels of 1650-1700 kWh/m2. Figure 2. Solar energy potential map of Kütahya province [21] In Kütahya province, the installed power of unlicensed photovoltaic solar power plants is 114.03 MW as of February 2020. 10,397.23 MWh of electricity was generated from these power plants in February 2020. The graph of installed photovoltaic solar energy power and electricity generation from these power plants covering the January 2016 - February 2020 period of Kütahya is shown in Figure 3. While the photovoltaic installed power in Kütahya was 1 MW in January 2016, this value has increased exponentially and reached 114.03 MW as of February 2020. When the electricity generation from solar energy with photovoltaic panels is examined, the production amount in January 2016 was 42.86 MWh, the production amount increased with the installed power and this value reached 10,397.23 MWh in February 2020 [2]. In Figure 4, the ratio of electricity generation from photovoltaic power plants to the total (lighting, residential, industrial, agricultural irrigation and commercial facilities) electricity consumption of Kütahya province can be seen. While the production / consumption rate was 0.3 ‰ in January 2020, this rate was 78.3 ‰ in February 2020. During the period examined, the ratio of the amount of electrical energy obtained from photovoltaic power plants to consumption reached up to 18% [2]. 92 Int J Energy Studies 2020;5(2):89-105 Table 1. General information for Kütahya districts Latitude Longitude Altitude Daily solar radiation Daily sunshine duration Annual ave. (o) (o) (m) (kWh/m2.day) (Hours) temp. (oC) Central 39.4 30 960 4.08 6.4 10.5 Altıntaş 39.1 30.1 1030 4.16 7.07 10.84 Aslanapa 39.2 29.9 1030 4.12 7.07 10.61 Çavdarhisar 39.2 29.6 1010 4.11 7.03 10.96 Domaniç 39.8 29.6 880 3.98 6.93 10.49 Dumlupınar 38.9 30 1225 4.22 7.21 10.33 Emet 39.3 29.3 900 4.07 7.14 11.21 Gediz 39 29.4 750 4.14 7.29 12.57 Hisarcık 39.3 29.2 760 4.07 7.26 11.92 Pazarlar 39 29.1 925 4.15 7.44 11.69 Simav 39.1 29 820 4.06 7.3 11.78 Şaphane 39 29.2 980 4.14 7.32 11.4 Tavşanlı 39.5 29.5 845 4.01 7.08 10.83 25000 140 120 20000 100 15000 80 10000 60 40 Production(MWh) 5000 Installed Capacity(MW) 20 0 0 July 2016 July 2017 July 2018 July 2019 July May 2016 May 2017 May 2018 May 2019 March 2016 March 2017 March 2018 March 2019 March January 2016 January 2017 January 2018 January 2019 January 2020 November 2016 November 2017 November 2018 November 2019 November September 2017 September September 2016 September 2018 September 2019 September Production (MWh) Inst.