CASE STUDY USING DIFFERENT TYPES OF PHOTOVOLTAIC CELLS. Ana Talida PACURAR, Cristian PACURAR, Dumitru TOADER

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1 , Brno, Czech Republic, EU CASE STUDY USING DIFFERENT TYPES OF PHOTOVOLTAIC CELLS Ana Talida PACURAR, Cristian PACURAR, Dumitru TOADER Politehnica University of Timişoara, Timişoara, Romania, EU m_talida@yahoo.com; cristian.pacurar@ct.upt.ro; dumitru.toader@et.upt.ro Abstract Photovoltaic electricity market has experienced a great growth in recent years, lamps fueled by solar energy sources are used more extensively in street lighting solutions. They work by a very simple principle: light during the day is converted into electricity by a solar panel, which in turn is stored in a battery. After, energy from the battery is converted back into an energy saving bulb light at night. Solar lamp is controlled by a small light sensor that automatically starts and stops the lamp. Power light is directly dependent on solar power panel, battery and economic bulb. Offer for sale of these public lighting is new in Romania. This paper presents a study realized used different types of photovoltaic cells: conventional and high-efficiency c-si, single-, double-, and triple-junction thin film technologies. Keywords: PV cells, solar energy, solar radiation, public lighting 1. INTRODUCTION Public lighting is designed to ensure orientation during the night and traffic safety for vehicles and pedestrians but also a satisfactory environment to daylight free hours. Public lighting must therefore accomplish light conditions, physiological, traffic safety, esthetic architecture and technical standards, according to the rational use of energy, to lower investment and annual costs of operation. Latest in lighting is LED bulb. The advanced technology used to operate this new step brought this product to the attention of consumers.[1] By grouping a number of LEDs to create a source of light, the results obtained were surprisingly significant as lighting and consumption expenses were reduced. Solar street light is powered by solar energy and wind power. The two ones work to transfer into electricity which will be stored in battery. The controller will turn on the switch automatically at night. The solar light will keep working till the controller turn off the switch. It can easily be assembled, no cables needed. The working voltage is so low that it won't hurt people. Silicon is most frequently used material for photovoltaic (PV) cell production at industrial level. Metalurgical silicon with a purity of 98% can be obtained(is obtained ) as a result of industrial processes Quality electronic silicone in liquid form is the result of even more chemical purification steps The last step is to obtain material doping P-type and N type. A PV cell must operate between 2 and 3 years to produce energy for its manufacturing process.[2] Most PV cells are made from purified silicon, which is doped with other elements to achieve the desired photoelectric properties. There are several basic kinds of cells: monocrystalline, polycrystalline and amorphous silicon (thin film) cells. In case of monocrystalline silicon cells, after its cooling, crystallized silicon is creating a single crystal. It is cut into thin strips which are then applied to other layers components of a PV cell. Their color is usually blue. [3] The disadvantages of monocrystalline cells are high cost production and low yield for a low light to produce energy for its manufacturing process. Polycrystalline silicon cells are formed during crystallization of more crystals. Cut into strips conducing to the achievement cell consisting of several crystals. They are also blue, but we can distinguish various reasons formed after crystallization. The advantages of this technology are: good efficiency cells and lower production cost. Their disadvantage is low efficiency in case of poor lighting. Cells are mostly used in industry for the production of PV panels with best value for money. Amorphous silicon cells - In this case silicon is not crystallized, but deposited on a sheet of glass. It has a grayish color. Benefits consist of a good performance in case of poor lighting and low production cost. The disadvantages are low

2 , Brno, Czech Republic, EU efficiency for high intensities of solar radiation and material degradation in a relatively short period of operation. Tandem cells are achieved by the combination of described above types of cells in the form of layers. This combination leads to the absorption of a wider spectrum of electromagnetic radiation to produce electricity. In this way improves conversion efficiency compared to a single cell. Production cost in this case is obviously higher. Thin film cells - this technology involves reducing the quantity of material used in the production of PV cells, but may also lead a decrease in conversion efficiency. This type of cell has become frequently used in terms of manufacturing low cost, low weight and flexibility of their panel. In this category are cells CdTe, CIGS and GaAs. Polymer cells - This type of cell is made from organic polymers and is one of the newest PV technologies. The cells are generally made by film (1 nm) of polyphenylene-vinyl carbon fullerenes. [4] 2. EXPERIMENTAL PROCEDURE One of the most important aspects in installing a photovoltaic system is solar radiation. Each geographical position has different characteristics depending on solar irradiation and it is chosen first the power of panel and then angle will be installed. Given the extensive support provided by governments around the world for renewable energy, there are many applications that can determine the needs for panel specific geographic areas. EU offers through the PVGIS (Photovoltaic Geographical Information System) - Geographic Information System for PV systems on site ( an application that can determine which panel we need a certain geographical area based on estimated power consumption. [] Performance of photovoltaic panels is temperature-dependent. Thus the greater temperature, the lower the efficiency photovoltaic panels to convert sunlight energy into electricity. It can be considered as indicative, a reduction of.3% efficiency photovoltaic panels for each degree of temperature increase.[6]. In this paper we study the situation of four LEDs, who deserved public lighting for a street in Timisoara, in order to choose the best choice for streets public lighting. These lamps are powered by solar cells, mounted with PV panels at an inclination angle of 4º, placed towards South. Each item has components: photovoltaic module, LED lamp, battery and regulator. We noted PV LED street lamp as PV LED Lamp 1, PV LED Lamp 2, PV LED Lamp 3 and PV LED Lamp 4. All four lamps have the same battery capacity of 1Ah. The regulator for three lamps is 12A/1V and for one is 24V/1A (PV LED Lamp 2). First PV LED lamp has monocrystalline silicon PV module, the module power is 1W. Second LED lamp has monocrystalline silicon PV module, the module power is 18W. We chose PV LED Lamp 3 with polycrystalline silicon PV module, PV module power is 1W. PV LED Lamp 4 polycrystalline silicon PV module, PV module power is 6W. Power of LED Lamp 1 and LED Lamp 2 is 3W. Power of LED Lamp 3 is 8 W and for Lamp 4 is 12 W. We measured voltage battery during ten days in December 211. The measurements were made from 8 a.m. until 4 p.m., with a step of 2 hours. In this experiment we proceed dates for 3 days: in 7 th, 12 th and 16 th December RESULTS AND DISCUSSIONS We present the temperature and total solar irradiation on a surface tilted with 4 deg. face toward South [6] in Timisoara during these experiments. This situation is presented in Table 1:

3 , Brno, Czech Republic, EU Tab. 1: Temperature and total solar irradiation on a surface tilted with 4 deg. face toward South in Timisoara during these experiments [7] Day Time/ Hour Air temperature [Celsius] Total solar irradiation [W/m2] ,18 89, ,2 68, ,3 67, , ,12 94, ,4 2, ,8 112, ,3 189, ,24 18, ,22 14, , ,19 186, ,24 134, ,36 228, ,3 3,1 The four types of PV LED lamps are presented in picture below. Fig.2: PV LEDs Lamp measured in this study One of the most important characteristic of photovoltaic cell is voltage measured at battery. We present for all four lamps the voltage depending by temperature and solar radiation. The measurements realised on 7th December 211, 12th December 211 and 16th December 211 starting at 8 am and finishing at 4 pm, at the same temperature for these lamps is presented in Figure 4, Figure and Figure 6. In Figure 3 is presented the measurements realised in 7 th December 211.

4 , Brno, Czech Republic, EU ,18 13,2 13,3 13,28 13,12 Temperature [ºC] PV LED Lamp 1 PV LED Lamp 2 PV LED Lamp 3 PV LED Lamp 4 Fig.3: Measurements performed in 7 th December 211, depending by temperature The measurements realised in 12 th December 211 is presented In Figure 4 and that was made in 16 th December 211 is presented in Figure ,4 12,8 12,3 12,24 12,22 Temperature [ºC] PV LED Lamp 1 PV LED Lamp 2 PV LED Lamp 3 PV LED Lamp 4 Fig. 4: Measurements performed in 12 th December 211, depending by temperature ,19 12,24 12,36 12,3 Temperature [ºC] PV LED Lamp 1 PV LED Lamp 2 PV LED Lamp 3 PV LED Lamp 4 Fig. : Measurements performed in 16 th December 211, depending by temperature We mounted these PV LED Lamps with solar PV module faced toward South and with a 4 deg. angle. The measurements realised on 7th December 211, 12th December 211 and 16th December 211 starting at 8

5 , Brno, Czech Republic, EU am and finishing at 4 pm, at the same total solar irradiation on a surface tilted with 4 deg. face toward South for these lamps is presented in next three figures ,1 68, 67, ,8 Total solar irradiation on a surface tilted with 4 deg. faced toward South [Wh/m2] PV LED Lamp 1 PV LED Lamp 2 PV LED Lamp 3 PV LED Lamp 4 Fig. 6: Measurements performed in 7 th December 211, depending by total solar irradiation on a surface tilted with 4 deg. faced toward South [Wh/m2] ,4 112,7 189,2 18,4 14,7 Total solar irradiation on a surface tilted with 4 deg. faced toward South [Wh/m2] PV LED Lamp 1 PV LED Lamp 2 PV LED Lamp 3 PV LED Lamp 4 Fig. 7: Measurements performed in 12 th December 211, depending by total solar irradiation on a surface tilted with 4 deg. faced toward South [Wh/m2] ,9 186, 134,9 228,1 3,1 Total solar irradiation on a surface tilted with 4 deg. faced toward South [Wh/m2] PV LED Lamp 1 PV LED Lamp 2 PV LED Lamp 3 PV LED Lamp 4 Fig. 8: Measurements performed in 16 th December 211, depending by temperature

6 , Brno, Czech Republic, EU 4. CONCLUSIONS PV LEDs lamp with monocrystalline silicon PV module are able to convert highest amount of solar energy into electricity compared with modules which has the same module power, but with polycrystalline silicon PV module. Also, we observed the differences between lamps with the same cells but different module power and the differences between different consumption of LED lamp. The photovoltaic cells functions in cold weather and this happens because PV systems are electronic devices which generate electricity from light. It is better to use solar module, addition to network independence, photovoltaic power offers many other advantages: simplicity of operation, low maintenance costs and lower environmental impact. LITERATURE [1] PAULESCU M., SCHLETT Z., ASPECTE PRACTICE IN CONVERSIA FOTOVOLTAICA, EDITURA MIRTON, TIMISOARA [2] TURNER J.A., A Realizable Renewable Energy Future, Science 3 July 1999, Vol. 28 no. 428,pp , DOI: /science [3] REBER S., HURRLE A., WILLEKE G., Crystalline silicon thin-film solar cells recent results at Fraunhofer ISE, Solar Energy, volume 77, Issue 6, december 24, pages [4] RAZYKOV T.M., FEREKIDES C.S., MOREL D., STEFANAKOS E., ULLAL H.S., UPADHYAYA H.M., SOLAR PHOTOVOLTAIC ELECTRICITY: CURRENT STATUS AND FUTURE PROSPECTS. SOLAR ENERGY XXX (211) XXX XXX [] PHOTOVOLTAIC GEOGRAPHICAL INFORMATION SYSTEM (PVGIS) - [6] JEFFERSON M., SUSTAINABLE ENERGY DEVELOPMENT: PERFORMANCE AND PROSPECTS. RENEWABLE ENERGY 26;31: [7] PAULESCU M., DUGHIR C., TULCAN-PAULESCU E., LASCU M., GAVRILA P., JURCA T., "Solar Radiation Modeling and Measurements in Timisoara, Romania: Data and Model Quality", Environmental Engineering and Management Journal (EEMJ) Vol.9, No.8, pp189 (21).