Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2025The impact of photovoltaic panels on the environment and yield parameters in an open field agrivoltaic system: A case study in Ayaş, Ankara
Senturk, Bilge; Oylek, Yelda; Kanar, Zeynep Sevim; Celik, Ridvan; Kurtulus, Gunes; Ozden, Talat
Agrivoltaic systems represent an innovative approach that integrates energy production and agriculture by installing elevated photovoltaic modules over farmland. In this study, the critical parameters on microclimate and microenvironment conditions — soil moisture and temperature, relative humidity, ambient temperature, photosynthetically active radiation, wind speed — and crop yield amount were monitored and analyzed in a single axis tracking AgriPV system installed in Ankara, Türkiye. Results indicate that under the 35 % coverage AgriPV system, photosynthetically active radiation decreased by 38.55 %. Additionally, soil moisture was found to be higher at 20 cm below under the AgriPV system compared to the reference field during the plant growth period. The yield data showed a considerable difference in crop amount under the AgriPV system across different harvest periods. The results are critically important for developing models in future phases that aim to predict and optimize the agricultural and ecosystem performance of AgriPV systems.
- MakaleAçık Erişim2023Assessment of photovoltaic module temperature estimation for four years with four different software; [Dört yıllık fotovoltaik modül sıcaklık tahmininin dört farklı yazılımla değerlendirilmesi]
Tolgay, Doga; Yakut, Muhammet Samet; Ozden, Talat; Akinoglu, Bulent G.
The software used today, on the estimation of module temperature of photovoltaic systems, seem very important to be analyzed. These estimates are crucial in future techno-economic and environmentally friendly analyses of the systems to reach better achievements for future generations. This is very important to reach lifetime analyses of long-term feasibility to find out payback time and the levelized cost of energy. The present work is based on this issue, to test the module temperature estimation formulas used by four commonly used software models, and to determine the most suitable software for temperature analyses of five different photovoltaic modules in Middle Anatolia. Outdoor truthful long-term testing is the main realistic approach to reach fundamental contemplations. After an introductory basic knowledge, the main materials and methods are discussed to enlighten the analysis. The main methodology is given and further prospects are enlightened. Four well-known software are analyzed using four years of outdoor testing of five different photovoltaic modules. Measured ambient temperature and solar irradiance are used in the categorization of the software estimation performances. PV*SOL appears to be superior at low irradiance and ambient temperature, whereas Helioscope appears to be superior overall.
- MakaleYayıncıda açık erişim2022Technical potential of rooftop solar photovoltaic for Ankara
Kutlu, Elif Ceren; Durusoy, Beyza; Ozden, Talat; Akinoglu, Bulent G.
Turkey, which has immense solar potential, has recently shifted towards solar energy and new renewable energy deployment regulations, including implementation and commercializing rooftop PV technologies. Thus, these require a detailed assessment to determine the power source's capability and convince the policymakers. To the authors' best knowledge, there is no available data or a city-based study for the rooftop PV potential in Turkey. Here, we present the first city-based rooftop PV potential study in Ankara. The technical PV potential calculations are sensitive to the suitable area ratio, module efficiency, and module area assumptions. This study proposes a new, free, reliable, and open-source model for estimating the rooftop PV potential, and it is adaptable to every roof type. The suitable roof area for PV panels is calculated using Helioscope software. Five different modules with different efficiencies and module sizes are modelled in Helioscope. The results showed that Ankara's total technical PV potentials for residential, public, and commercial buildings are 1.15 TWh/year, 55 GWh/year, and 26.8 GWh/year, respectively. Best results are obtained by Mono-Si Halfcut (M2) and Thin Film (M5) modules in residentials, M2 and Mono-Si Bifacial Modules (M3) in Public and Commercial Buildings.
- MakaleAçık Erişim2022Analysis and assessment of daily and seasonal photovoltaic heat island effect on Sekbandemirli rural region by local weather data records; [YEREL METEOROLOJIK VERI KAYITLARI ILE SEKBANDEMIRLI KIRSAL BÖLGESINDE GÜNLÜK VE MEVSIMSEL FOTOVOLTAIK ISI ADASININ INCELENMESI VE DEǦERLENDIRILMESI]
Demirezen, Emre; Ozden, Talat; Akinoglu, Bulent G.
Photovoltaic Power Plants have a considerable share among solar energy conversion technologies toward environmentally sustainable and economically feasible electricity production. However, when a rural region's land surface formed by natural soil types is covered by a Photovoltaic Power Plant (PVPP)'s dark-colored solar modules in large numbers, an artificial albedo (reflectivity) change is expected on that surface. Because of the heat exchange between these modules and the air surrounding them due to albedo alteration, the region's natural weather conditions may experience Photovoltaic Heat Island Effect (PVHIE) as a result of external and time-dependent air temperature oscillations caused by the warming-cooling cycles of solar modules. To observe and analyze a possible PVHIE trend, it has been conducting a field study project since October 2017 for a PVPP near the Sekbandemirli rural region in the Kutahya city of Turkey. The weather data, including air temperature and wind (direction and speed) at every 10-minute and hourly intervals, are collected by the three weather monitoring stations installed at the specific locations inside and outside the PVPP field. The plant's hourly average power output and module temperature data can also be monitored. After conducting statistical, correlational, and graphical analyses, the results show some temporal PVHI formations at the PVPP field center daily and on a seasonal basis. The plant center's air temperature tends to be warmer (up to the 6°C difference) during daytimes and colder (up to the (-3)°C difference) during nighttimes.
- MakaleAçık Erişim2022A countrywide analysis of 27 solar power plants installed at different climates
Ozden, Talat
The world is still heavily using nonconventional energy sources, which are worryingly based on carbon. The step is now alternative energy sources hoping that they will be more environmentally friendly. One of the important energy conversion forms by using these sources is photovoltaic solar systems. These type of power plants is on the increase in everyday on the world. Before investment a solar power plant in a specified region, a techno-economic analyse is performed for that power plant by using several meteorological data like solar irradiance and ambient temperature. However, this analyses generally lacks evaluation on effects of climatic and geographical conditions. In this work, 5 years of data of 27 grid-connected photovoltaic power plants are investigated, which are installed on seven different climate types in Turkey. Firstly, the power plants are categorized considering the tilt angles and Köppen–Gieger climate classification. The performance evaluations of the plants are mainly conducted using monthly average efficiencies and specific yields. The monthly average efficiencies, which were classified using the tilts and climate types were from 12 to 17%, from 12 to 16% and from 13 to 15% for tilts 30°/10°, 25° and 20°, respectively. The variation in the specific yields decrease with elevation as y(x) = − 0.068x + 1707.29 (kWh/kWp). As the performances of photovoltaic systems for some locations within the Csb climatic regions may relatively lower than some other regions with same climate type. Thus, techno-economic performance for PVPP located in this climate classification should be carefully treated.
- MakaleAçık Erişim2020Comparison of the Models for Solar Photovoltaic System Performance Calculations for Ankara (Middle Anatolia)
Ozden, Talat; Karaveli, Abdullah Bugrahan; Akinoglu, Bulent G
In a techno-economic analysis, to reach truthful feasibilities, accurate performance calculation of PV systems is a must. There are manymodels/calculation schemes to estimate PV module performances. In this study, we compare the estimation of three software (PV*Sol,PVsyst, HelioScope) using a whole year field data obtained in Ankara, for five-module types. The reason for these choices of thesoftware is their common utilization by designers, financing bodies and investors. The results of the preliminary analysis showed thatthe calculation methods for the PV systems performances should be carefully evaluated and used as they contain quite many locateddependent empirical parameters, and distinctions in the fabricated modules. Therefore, the present article focuses on the systems thatuse the module types of Mono-Si, Poly-Si, µc-Si/a-Si, CIS, and HIT. The comparisons showed that the estimation accuracies of thesoftware are reasonable, yet the software Helioscope performs better than the others for the weather conditions of Ankara, MiddleAnatolia.
- MakaleAçık Erişim2020One-year performance evaluation of two newly developed back-contact solar modules in two different climates
Ozden, Talat; Carr, Anna J.; Geerligs, Bart (L.J.); Turan, Rasit; Akinoglu, Bulent G.
To a certain extent, the photovoltaics industry is well developed, and the performance and expected yield of standard photovoltaic modules are well documented and researched. However, newer more efficient photovoltaic cell and module technologies are being developed all over the world. Outdoor testing of new photovoltaic technologies is very important to understand and validate their reliability and performance under different environmental conditions. For the first time, one year of monitored performance data is presented and analyzed for two high efficiencies interdigitated back contact prototype mini-modules at different locations, having different climates. The test results of a commercial heterojunction with intrinsic thin-layer” module are also presented for comparison. The results showed that the two mini-modules remained stable for the duration of the test period, and showed no signs of degradation. They did perform significantly differently due to the different climatic conditions. The results also show that the combination of ambient temperature difference together with relative humidity impacts the performance of the modules. Calculated outdoor yearly efficiencies are 19.05% and 18.36% for two integrated back contact mini-modules tested in Petten-Netherland and Ankara-Turkey, respectively. The temperature coefficients of the modules are also calculated and compared with two commercial photovoltaic modules.
- MakaleAçık Erişim2020Solar irradiation on the rear surface of bifacial solar modules: a modeling approach
Durusoy, Beyza; Ozden, Talat; Akinoglu, Bulent G.
The transition in the energy sector has started with the growing population leading to the growing energy demands. The use of photovoltaic (PV) technologies has become a crucial way to meet energy demand. There are many ongoing studies for increasing the efficiency of commercial PV modules. One way to increase the energy yield of the PV modules is to use bifacial solar panels by capturing the rear side illumination as well. One of the challenges for estimating the bifacial module performances is to calculate the solar irradiation impinging on the rear side. Many models presented up to now require high computational power, and they are challenging to implement real-life conditions. In this paper, a simple physical modeling approach is presented to calculate the rear side solar irradiation incident on the bifacial modules. For the rear side irradiance estimation, the maximum difference between the measured and calculated rear side irradiance value is approximately 10 W/m2. The model does not require high computational skills since it is neither focused on the view factor nor ray tracing methodologies but instead uses solar geometry. The yield of the module is also modeled, calculated, and compared with the measurements.
- BildiriYalnız künye2020Nine Years Long Term Performance and Degradation Assessment of Two On-Grid PV Systems
Ozden, Talat; Ozgun, Ensar Mesut; Keles, Bedirhan; Akinoglu, Bulent G.
Nine years outdoor testing of the two on-grid PV systems at Central Anatolia under the same ambient conditions is very important to be discovered toward transition to renewables. The systems consist of a monocrystalline silicon and micro-crystalline silicon based amorphous thin film PV technologies. The analyses are carried out on monthly based using the outdoor efficiencies. In addition, degradation rates of these systems are calculated and compared with each other and also with international literature. It is also compared the results using the degradation rates of an earlier study carried out using measurements of a shorter period of time.
- MakaleAçık Erişim2020AN EXTENDED ANALYSIS OF THE MODELS TO ESTIMATE PHOTOVOLTAIC MODULE TEMPERATURE
Ozden, Talat; Tolgay, Doga; Yakut, M. Samet; Akinoglu, Bulent G.
To estimate the performance of the photovoltaic power systems is the key issue in their techno-economic feasibility analysis. Performances, on the other hand, strongly depends on the module temperatures of the photovoltaic systems. In this study, we evaluated the performance of ten different module temperature estimation models using the measured outdoor data of five different modules. The modules are installed at the rooftop of a building located at Central Anatolia where the climate is cold and semi-arid. The results showed that the models having smaller number of parameters perform better than the others. We concluded that such analysis should be carried out at different ambient conditions so that the best performing models for the site can be obtained. Another outcome of the study is that the seasonal evaluation of the performance of the models should be carried out.
- BildiriAçık Erişim2018Thermal modeling and verification of pv module temperature and energy yield using outdoor measurements for Ankara, Turkey
Tuncel, Bilge; Akinoglu, Bulent G.; Ozden, Talat; Balog, Robert S.
Ankara is in the Central Anatolia region of Turkey where the climate is dry-continental with an annual solar insolation of around 1750 kWh/m 2 . In the transition to renewable energy, detailed analyses are required to ensure effective and economic utilization of the available solar resource. An essential part of these analyses is to calculate expected energy yield. For photovoltaic (PV) systems, this includes the effect of temperature on the PV efficiency, which determines the power yield of the PV modules. In this study, a first-principles thermal modeling approach is improved by adding the speed and direction of wind across the PV module into a forced convection term as well as including the temperature dependency of the module conversion efficiency. The analytical model is based on the principle of conservation of energy and uses meteorological data that are readily available from most state meteorological services. The mathematical analysis is suitable to predict the performance of a proposed PV installation without the time and expense of installing and monitoring a pilot system. The mathematical model is compared against measured data from the METU-GUNAM Outdoor Test Facility in Ankara to validate the methodology. Preliminary analyses showed that the model performs well especially during sunrise and sunsets shoulders of the diurnal cycle with a deviation of only a few W/m 2 for the electrical power yield and about 2°C for the module temperature. However, these deviations could become as large as 12 W/m 2 and 8°C at solar noon which suggests that the model still requires further improvement. In general, this error was found to be less that obtained by using basic explicit correlation methods and offers the advantage that it can be used for other geographical environments for which insolation and meteorological data is available without needing to construct a test-site.
- BildiriAçık Erişim2018Performance and degradation analyses of two different pv modules in central anatolia
Ozden, Talat; Akinoglu, Bulent G.; Kurtz, Sarah
Ankara (latitude: around 40°N) is in Central Anatolia and the climate is dry continental. Due to the rapid transition to renewable energy policies of Turkey it is now a must to complete truthful feasibility analyses for solar power systems countrywide. Long term performance and degradation analyses have been carried out by the authors for three different arrays and many research results appearing in the literature are summarized. Present research analyzes the outdoor testing results of two PV modules monthly data. One of the modules has multi crystalline silicon (Poly-Si) cells and the other is thin film silicon (amorphous Si / microcrystalline Si tandem structure - a-Si/μc-Si) cells. The results showed that in five years the average yearly efficiency decreases from 14% to 11% for Poly-Si (14.72% is the nameplate Standard Test Condition (STC) efficiency) and from 8% to 6% for thin film modules (9.15% is STC efficiency). Our calculations are based on measured solar global-horizontal irradiance from which we calculated plane-of-array irradiation using an anisotropic sky model. We present the details of these analyses and degradation rates for the two types of modules to be used in long term feasibility analyses.
- BildiriAçık Erişim2018Determining photovoltaic module performance and comparisons
Karaveli, Abdullah Bugrahan; Ozden, Talat; Akinoglu, Bulent G.
Knowing electricity production potential of a photovoltaic (PV) system prior to installation is very beneficial for the investor to see the feasibility of the investment. There are three procedures that can be followed to calculate the potential electricity production of any system under different conditions. These are installation of sample systems and gathering data over time, the use of some databases/software programs to reach the performances and developing new model/methodology to make these estimations. It is obvious that installation of PV systems everywhere is neither technically nor economically conceivable. On the other hand, global software programs may not reflect local conditions to calculations. Consequently, there is a need to develop methodology that is able to derive location specific equations and coefficients and make accurate estimations. Its accuracy can be controlled by validating the results for some locations with the measured values from already installed PV power plants (PV PP). So, in this study we initially develop a methodology to calculate efficiency and electricity production performance of some modules for Ankara and compare the results with the measured values owing to the system installed on the roof of the Middle East Technical University Solar Energy Research Center (METU GUNAM) in Ankara/Turkey. The methodology initially calculates solar irradiation falling on the modules that is the input. Then the performance of the module is calculated by using developed methodology. There are also some online software programs to calculate the performances, such as EU PVGIS and PV WATTS. We analyzed and used these software programs and compare their results with the results of newly developed methodology. As proven through mean-bias error (MBE), root-mean-square error (RMSE) and mean absolute error (MAE) statistical comparison methods, the methodology of this study has given the most accurate results.
- BildiriAçık Erişim2018Impacts of a photovoltaic power plant for possible heat island effect
Demirezen, Emre; Ozden, Talat; Akinoglu, Bulent G.
Today, solar energy conversion technologies take a significant place within the efforts of obtaining renewable and sustainable energy around the world, and show a rapid progress. One of the most common technologies is photovoltaic power plants (PVPP) which are built using PV modules that provide electricity directly from sunlight. These plants are qualified as one of the pioneering applications among clean energy production methods. However, as the modules cover large areas and as they are produced by mostly dark-colored solar cells, an environmental debate has already been opened via some recent studies in the literature: Do they alter the solar reflectivity (albedo) of the region's surface where they are installed, and in turn affect the typical microclimate characteristics of that region such as the local air temperatures, humidity, pressure and wind speed? Considering also the additional heat that the modules radiate while producing electricity, the main probable result should be expected as Heat Island Effect (HIE). HIE has been particularly discussed for about last 10 years. Basically, this effect defines the day-night and inter-seasonal variations of local temperatures due to artificial changes on the natural land surface. Accordingly, when an urbanized area is compared with the neighboring rural areas, the difference is specifically named as Urban Heat Island (UHI) effect. In the present work, we are conducting a field research with in-situ measurements taken by the two weather monitoring stations inside and outside a PVPP in the district Tavsanli (Kutahya, Turkey). We also provide the meteorological data of Tavsanli station from Turkish State Meteorological Service (TSMS), which is the nearest weather monitoring station to the PVPP under inspection. These stations have been collecting the data of air temperature, relative humidity, average wind speed and atmospheric pressure every 10 minutes since October 2017. We used two statistical methods to compare and interpret the first 8-month data of all the three stations. We considered the statistical significance tests for both the first 8 months as a whole and dividing it into two 4 months before and after the PVPP becomes operational. We found that the measurements of the three stations differ significantly for most of the weather parameters. We also carried out pairwise tests and showed that each pair has significant differences for most parameters.
- MakaleAçık Erişim2017Long term outdoor performances of three different on-grid PV arrays in central Anatolia – An extended analysis
Ozden, Talat; Akinoglu, Bulent G.; Turan, Rasit
Long term outdoor testing of the PV systems at different climatic conditions or different systems under the same ambient conditions are extremely important in producing policies for the transition to renewables. The present research is the testing of three different PV systems under the same climatic conditions of central Anatolia, after four years of operation. The systems consist of a mono-Si, an a-Si thin film and a CdTe thin film arrays. Different calculation procedures of the input solar irradiation on tilted surface are used for comparison. Performances together with degradation rates are computed using different procedures and also using the measured solar data of 20 km away from the installed systems. The accuracy is verified using 4 months of simultaneous measurements. The results showed that the aforementioned different input calculation procedures of the performances are important and determinant. The 44-months-average efficiencies of these three systems are calculated to be 11.86%, 6.40% and 5.30%, respectively. The degradation rates of these systems are obtained as 0.40%, 1.88% and 10.60%, respectively. Although the degradation rates that are calculated for the first two systems are quite similar to those appeared in the literature, CdTe system is considerably higher than those given in the literature.
- MakaleAçık Erişim2015Outdoor efficiency analyses and comparison of on-grid CdTe and μc-Si/a-Si thin-film PV systems for three years in Ankara - Turkey
Ozden, Talat; Yardim, Ugur; Akinoglu, Bulent G.; Turan, Rasit; Turan, R; Gunes, M; Sariciftci, NS; Varlikli, C
The present paper is mainly a comparison of the performances of two PV systems under outdoor conditions in Ankara. The systems are grid connected and consist of two PV arrays. The types of these PV arrays are CdTe thin film and amorphous silicon/micro-crystalline-based (μc-Si/a-Si) arrays. They are operated for 3 years; 2012-2014. Yearly averages of monthly efficiencies of these two systems working under the same ambient conditions are 6.88%, 6.65%, 6.80% and 6.64%, 5.86%, 5.25% for μc-Si/a-Si and CdTe, respectively. Using these values, simple calculation results for the degradation rates per year are about 0.39%/year and 6.98%/year, respectively for these two types of systems.
- MakaleAçık Erişim2015A low cost outdoor testing facility for detailed photovoltaic device performance characterization
Ogulgonen, Guvenc; Ozden, Talat; Yardim, Ugur; Turan, Rasit; Kincal, Serkan; Turan, R; Gunes, M; Sariciftci, NS; Varlikli, C
Long term outdoor performance monitoring is the ultimate method to capture the long term performance characteristics of PV devices. As time consuming as this process might be, it is the only way in which the local environmental condition versus PV device characteristics may be captured when making investment decisions. This data needs to be captured at least once through the seasonal cycle. It needs to be correlated to the environmental conditions, this monitoring climatic conditions is a requirement. Solar irradiation conditions must be monitored over a range of inclination angles - direct, diffuse and reflected components must be ideally captured separately. The panels must be held at maximum power generating point through the varying illumination conditions. Periodic IV traces must be captured, in addition to the power output to understand mechanisms of degradation, if present. Furthermore, the IV curves must be summarized in terms of relevant performance metrics. This work describes an outdoor testing facility that addresses all the aforementioned requirements. Reliable equipment selections coupled with adequate modelling strategies allow for the generation of a robust and accessible database of performance data.