Compressed sensing current mapping methods for PV characterisation

The Compressed Sensing (CS) sampling theory has been combined with the Light Beam Induced Current (LBIC) method, to produce an alternative current mapping technique for photovoltaic (PV) devices. Compressive sampling of photocurrent is experimentally implemented using a Digital Micro-mirror Device (DMD). The main advantage of this new method for current mapping is that measurement time can be significantly reduced compared to conventional LBIC measurement systems. This is achieved mainly by acquiring fewer measurements than a raster scan would need and by utilizing the fast response of the micro-mirror array. Two different experimental layouts are considered in this work. The first is a small area optical set-up based on a single wavelength laser source. The second layout utilizes a commercial Digital Light Processing (DLP) projector through which compressive sampling is applied. Experimental results with both experimental schemes demonstrate that current maps can be produced with less than 50% of the measurements a standard LBIC system would need. The ability to acquire current maps of individual cells in encapsulated modules is also highlighted. The advantages and drawbacks of the method are presented and its potential to significantly reduce measurement time of current mapping of PV cells and modules is indicated.