Persistent luminescent material SrAl2O4: Eu2+, Dy3+ is widely used and studied for energy efficient applications. A study of SrAl2O4:Eu,Dy; SrAl2O4:Dy, and undoped SrAl2O4 material was conducted. Improvements for the mechanism of persistent luminescence have been suggested, that involve tunnelling of electron from trapping center to Eu3+, and the proof for stable Dy4+ existence in strontium aluminate has been presented. Undoped material luminescence has been observed, consisting of trace impurity and intrinsic defects luminescence.The results of this work give new knowledge and improve the existing concepts of persistent luminescence in Eu activated strontium aluminates. They also open some possibilities for wider applications of persistent phosphors.