Petru Adrian Cotfas

Current-voltage characteristic raising techniques for solar cells. comparisons and applications

Interpreting the current- voltage I–V characteristic of the solar cells gives important information about functional parameters. The paper presents a comparison between the most important techniques of raising the I–V characteristic for solar cells. The improvement realized for raising the characteristic using a capacitor as a load resistance is also presented. A new method to determine the series resistance is developed using the I–V characteristic, and the comparison with the previously methods is also made.

Monthly average daily global and diffuse solar radiation based on sunshine duration and clearness index for Brasov, Romania

The main objective of this study is to develop single location appropriate models for the estimation of the monthly average daily global and diffuse horizontal solar radiation for Brasov, Romania. The study focuses particularly on models based on the sunshine duration and clearness index. The data used for the calibration of the models were collected during a period of 4 yr, between November 2008 and October 2012, at the Transilvania University of Brasov. The testing and validation of the models was carried out using data from the online SoDa database for Brasov for the year 2005. Different statistical error tests were applied to evaluate the accuracy of the models. The predicted values are also compared with values from three other known models concerning the global and diffuse solar radiation. A new mixed model was developed for the estimation of monthly average daily global horizontal solar radiation. The data processing was performed by means of a real-time interface developed with LabVIEW graphical programming language. The parameters taken into account were the relative sunshine, the clearness index, the extraterrestrial radiation, the latitude and the longitude. The methodology is simple and effective and may be applied for any region. Its effectiveness was proven through comparison with global models.

The methods to determine the series resistance and the ideality factor of diode for solar cells-review

The most important and accessible methods to determine the series resistance Rs and the ideality factor of the diode, m, for the solar cell are presented in this paper. The values of the two parameters obtained for a monocrystalline silicon solar cell with an area of 9cm2 are also presented comparatively. The measurements were realized using the NI ELVIS platform and the Solar Lab board, developed by the authors.

Multifunction iLab implemented laboratory

This paper introduces a new and flexible Multifunction System. By using LabVIEW 2010 Graphical Programming and or VEE-Pro with the new class of Agilent USB Devices in this application, at the University Transylvania of Brasov was developed a Flexible Laboratory Instrumentation System (FLIS) for new nanostructurated materials. This development offers great benefits to university research laboratories which need flexible systems that can be configured easily, to match the testing needs. At the same time, this FLIS Measurement System can be remotely controlled using MITs iLab Shared Architecture and is providing a uniquely modern, Web-controlled collaborative platform in research and education.

Remote SoC/FPGA platform configuration for cloud applications

The growing development of Cloud Computing raised the need of making hardware available “as a Service”. Reconfigurable hardware - like FPGA (Field Programmable Gate Arrays) - makes the ideal candidate for being integrated into Cloud systems due to their high flexibility and scalability. This work describes the design and implementation of a remote reconfigurable FPGA-based SoC (System on Chip) with a Service-oriented configuration interface over the Internet, and underlines several solutions in order to meet the specific challenges raised by this type of integration. The FPGA board (that can be at a remote location) is configured by a Web Service linked to a JSP (JavaServer Pages) Web-page where the user can provide a bitstream configuration file for the Programmable Logic (PL). On the SoC/FPGA board, dedicated software has been developed to run on the embedded Processing System (PS), managing the downloaded bitstreams and configuring the PL.

FPGA LabVIEW Programming, Monitoring and Remote Control

NI ELVIS is an educational design and prototyping platform from National Instruments Corp. based on NI LabVIEW graphical system design software. The platform is used for teaching concepts in areas such as instrumentation, circuits, control, communication, and embedded design in a hands-on, interactive manner. NI ELVIS contains an integrated suite of the 12 most commonly used instruments â?? DMM, oscilloscope, function generator, MIO, Counter etc - in a compact, rugged, laboratory-friendly form factor. A new instrument, the Digital Electronics FPGA Board has been added to the NI-ELVIS platform in order to help educators teach concepts of FPGA programming. This paper presents an example of graphical FPGA programming and monitoring using the Digital Electronics FPGA Board and LabVIEW FPGA graphical programming..

Characterization of Photovoltaic–Thermoelectric–Solar Collector Hybrid Systems in Natural Sunlight Conditions

AbstractTwo new hybrid systems incorporating photovoltaic, thermoelectric, and solar collector components were designed and characterized under natural sunlight conditions. Two types of photovoltai...

RELab - virtual laboratory of the renewable energy

The paper presents a very useful, innovative, compact laboratory, which is simple and complex at the same time. This virtual laboratory covers an important part of the renewable energy: photovoltaic energy, wind energy and solar thermal energy. The SolarLab board and the educational platform NI ELVIS II are the “heart” of the RELab laboratory. The complex software developed in LabVIEW is also presented. ReLAB allows the realization of over thirty lab experiments.

FPGA-enabled hardware multitasking applications in energy harvesting laboratories

This work describes the technical details of a novel methodology which enables the parallel deployment and execution of hardware applications onto the same FPGA chip using dynamic partial reconfiguration. Our approach, which makes use of the PCAP (Processor Configuration Access Port) available on the latest generation of Xilinx Zynq Systems-on-Chip, allows the processing system to operate a fast partial reconfiguration of the programmable logic with little logic overhead. The advantages brought by this technique, like scalability, high performance and dynamic management of the programmable logic are being put to use in implementing laboratory works involving running the mathematical models of energy harvesting sources. This allows the same FPGA development board to be used by several student at the same time for running their applications. Thus, this is part of a larger research effort in which we aim to develop remote online hardware design laboratories with hardware multitasking support.

Simulated, hands-on and remote laboratories for studying the solar cells

There are many studies in the literature related to the introduction in the engineering curricula of simulated laboratories and, more recently, of remote laboratories to extend the area of applications, nowadays limited by the labs endowment and to use creatively the advantages of e-learning. The paper aims to present a solution for the experiments related to the solar cells field. The presented solution combines the three existing laboratories, namely simulated, hands-on and remote laboratories. The solution put together the software applications Multisim and LabVIEW, the hardware NI ELVIS and the SolarLab board developed by the authors. The choice was based on the easiness of exchanging data between software applications, the speed of creating electronic prototypes offered by NI ELVIS, the large number of lab works on testing and characterization of solar cells provided by the SolarLab board and the easiness of performing remote laboratories using the web publishing tool in LabVIEW. The study was conducted within the solar cells course held for students from Applied Electronics, Physics Engineering and for other courses that have as partial subject the solar cells. The results were obtained based on the feedback from students as well as the correctness in performing lab works by the students. During hands-on and remote labs, the students support the idea of combining classical instrumentation, virtual instrumentation and modern tools, such as SolarLab.