In this work, complex photoconductivity and photo-induced piezoelectricity studies were performed for the AgGaGe3Se8 single crystals doped by In, Sn and Cu with content 5% in weighting units. The principal role of the intrinsic cationic and anionic defects is demonstrated. The photoconductivity and optical absorption spectra show substantial changes of effective energy gap and steepness of absorption edge. The role of optical transitions between the localized states in the presence of Sn, Cu, In impurities is explored. Piezoelectric studies under external laser illumination have shown significant role of dopants on the piezoelectric constants values and their anisotropy. Clear photo-induced jumps were discovered. The discussion is performed within the framework of crystallochemistry analysis and quantum chemical evaluations. Possibility of production of optically operated piezoelectric triggers is proposed.