Design and application of autonomous data acquisition systems used as calibration and qualification tool in photovoltaics

Abstract

In the paper basic design rules and possible applications of specialised autonomous data acquisition systems (DAS) in photovolatics (PV) are discussed. Their usefulness for both estimation of PV modules rating and prediction of the overall PV system actual performance, especially at strongly changeable weather and low insolation conditions, is presented. Some technical guidelines how to measure solar irradiation and current-voltage (I-V) curves of PV modules and big PV arrays are given. Examples of analysis and presentation of data stored by several installed systems are shown. Finally, new concept of modular PV DASs developed in Solar Lab which allows to reduce cost of installation yet increasing flexibility and extendibility of the PV monitoring systems is described. The concept is based on fully self-contained functional PVDA-Modules (PV Data Acquisition Modules). The heart of PVDA-Module is an 8-bit PIC family microcontroller (RISC-type). Each module is uniquely addressed and it communicates with PC computer, i.e., receives commands and/or exports stored data via RS485 bus with baud rate up to 100 kB and distance up to 1.2 km. Several examples of PVDA-Modules are given. A substantial list of representative references may be helpful for those who are going to get involved in photovoltaic measurement and monitoring.