Measurement & Analysis in PV Systems VALENTIN DOGARU ULIERU*, COSTIN CEPISCA**, TRAIAN DANIEL IVANOVICI*, ALIN POHOATA*, ADELA HUSU*, LUCIA PASCALE* *Electronics, Telecommunications and Energetic Department Electrical Engineering Faculty Valahia University of Targoviste, CAROL I, no.2, Targoviste, ROMANIA ** Electrical Engineering Faculty POLITEHNICA University of Bucharest dogaruvalentin@gmail.com, costin@wing.ro, traian_20@yahoo.com, alinpohoata@yahoo.com, adelahusu@yahoo.com, lucia_p2005@yahoo.com www.valahia.ro, www.upb.ro Abstract: - Data-acquisition systems are widely used in renewable energy source (RES) applications in order to collect data regarding the installed system performance, for evaluation purposes. The aim of this paper is to introduce a system developed for monitoring PV solar system using a novel procedure based on virtual instrumentation. The measurements and processing of the data are made using high precision I/O modular field point (FP) devices as hardware, a data acquisition board (PCI 6023 E) as software and the package of graphic programming, LabVIEW. The system is able to store and display the values of current and voltage, simultaneously trace characteristics (current-voltage, power-voltage, power-charge resistance), present the measured parameters (during the data acquisition) in tables, continuous acquisition and save data into files for future processing. Key-Words: - data acquisition, photovoltaic systems, LabVIEW, renewable energy. 1 Introduction The development of photovoltaic systems is accompanied by a rapid adaptation of measurement and control systems to the latest trends in digital techniques and computer-aided measurement [1]. The specialized photovoltaic (PV) data acquisition systems (DAS) have been recognized as an inevitable tool in the PV monitoring systems and the data collecting for the optimizing the performance of energy conversion [2]. Since many years, different DAS have been used in different equipment, to evaluate: - the performances of solar cells and modules in outdoor conditions; - long term stability and reliability of components of PV systems (PV modules and arrays, charge controllers, inverters etc.) - performance of different PV devices in strongly chargeable conditions; - theoretical assumptions and analyses. The range of tasks proceeded by a PV DAS is usually limited to control of solar irradiation, the current-voltage (I-V) curves of PV modules and energy flow. In the last years, the cost of computer and electronic equipment designed for data acquisition decreases and there are good reasons to install accurate and sophisticated PV monitoring systems. The hardware and software development makes possible new technical solutions for PV DAS and, in this context, this paper refers to a Romanian PV power station and a new monitoring and control system. The proposed system consists of a set of sensors for measuring both meteorological and electrical parameters (photovoltaic voltage and current). The collected data are first conditioned using precision electronic circuits and then interfaced to a PC using a data-acquisition card. The LabVIEW program is used to further process, display and store the collected data [9]. The equipment is capable of real time signal measuring giving information about the performance of the PV power plant, as well as of the energy quality generated by it. The proposed architecture permits the system development and has the advantage of flexibility in the case of changes. LATEST TRENDS on CIRCUITS ISSN: 1792-4227 137 ISBN: 978-960-474-198-4