Low-Cost Instrument for Tracing Current-Voltage Characteristics of Photovoltaic Modules

Abstract

This  paper  presents  a  simple,  robust  and  low-cost instrument  for  tracing  current-  and  power-voltage  characteristics  of photovoltaic   modules   or   low   voltage   strings   using   either   an oscilloscope or a LabVIEW application developed for this purpose. It consists  of  a  flexible  electronic  circuit,  developed  from  a  previous work,  based  on  a  fast  varying  load,  built  with  a  power  MOSFET, which  is  controlled  by  means  of  a  suitable  gate-source  voltage control signal in order to improve the tracing of current- and power-voltage characteristics on an oscilloscope. The new developments of this  work  include  a  low-cost   DAQ  system  and  an  application developed  in LabVIEW,  which  enhances  the  functionalities  and flexibility of the current-voltage tracer. The robustness was strongly improved  in  view  of  field  tests  for  fault  diagnosis  analysis.  All details   of   the   electronic   circuit   are   shown   in   this   paper   and experimental results obtained with the new instrument are presented.