Energy harvesting is a promising concept that can be used in the development of smart textiles to solve one of the major issues: energy supply. Producing PVDF piezoelectric fibers is a possible way. However, to ensure the piezoelectric character and lead an electromechanical conversion its β phase is needed. The modification of crystalline phases is linked to the processing parameters. In-situ Raman spectroscopy measurements are made on a spinning device used for new synthetic fibers developments or small productions. The content of the crystalline phases α and β is measured for the first time at key points of such process.