Educational PV System at the "Politehnica" University of Timişoara Dumitru Toader
Ioan Luminosu
Department of Physics Foundations of Engineering "Politehnica" University of Timişoara Timişoara, Romania
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Physics Foundations of Engineering "Politehnica" University of Timişoara Timişoara, Romania
[email protected]
Aldo De Sabata
Dan Mihai Negrea
Faculty of Electronics and Telecommunications "Politehnica" University of Timişoara Timişoara, Romania
[email protected]
Physics Foundations of Engineering "Politehnica" University of Timişoara Timişoara, Romania
[email protected]
Abstract—The photovoltaic system within the "Politehnica" of University of Timişoara, Romania has a surface of the PV cells of 16.06 m2 and a total surface of the panels of 18.30 m2. In the period April 2011 - February 2012 it worked with an average efficiency of 12.66% and with an annual energy efficiency of 1267.5 kWh/kWp. The installations injects electrical energy in the public grid. The PV system is used for educational practical applications for Master degree students in Solar Energy, for realization of dissertation theses and for public dissemination of information on solar energy. An assessment of the performances of the system based on measured data is provided in this communication. The results are useful for solar energy users interested in installing PV systems in the region. Keywords-solar energy; photovoltaic cells; efficiency; education
I.
INTRODUCTION
PV systems minimize the number of intermediary components between the primary power source, the Sun, and the end user with respect to other electrical energy generation systems. Therefore, the losses in the intermediary components are also small. On a global scale, the installed capacity has increased from 22900 MWp to 39529 MWp in 2010 with respect to 2009, i.e. an increase of more than 72% [1, p. 14]. The electrical energy produced by a PV system can be stored or it can be delivered to the public grid. Several possibilities to store the produced energy have been shown to be viable. The solar energy supplied pump systems contain three components: the PV system, DC motors and pumps [2]. Starting the pumps requires a minimum level of solar insolation, after which the flow rate of the volume of water is a function of the intensity of the solar radiation. The annual efficiency of the PV supplied pumping system is around 4%, but it can raise to 8% on a season basis and it can reach a maximum of 13%. For the hybrid PV-Diesel-Accumulators systems, an optimal correlation of the start and stop functions of the motor
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and the charging regulator ensures a 20-year lifetime for a power of the inverter of 10 kW and a capacity of 57 kWh [3]. The reasons for making investments in PV systems are: protection of environment, alternative to nuclear power and technological accessibility [4]. In PV systems exploitation, depositions on the surface of the glass reduce the transmittance up to extinction. The transmittance decreases with the increase of the angle of incidence, it depends on the dimensions of the dust particles and on the wavelength of the radiation in function of the criterion quantity α = πD / λ (D - diameter, λ - wavelength). For α
