The energy absorption characteristics of grid stiffened (isogrid) E-glass/Polypropylene (PP) composite panels were investigated under transverse load in both quasi-static and dynamic impact conditions. Under quasi-static loading, the panels loaded on rib side absorbed more energy than on skin side. Under dynamic impact, however, the panels loaded on skin side absorbed more energy than rib side. The energy absorbed was almost twice under dynamic impact than quasi-static loading. Vibration tests were also performed and it was concluded that the oscillations observed during the impact event could be attributed to structural resonances of the impactor, isogrid panel or both combined. Quasi-static test results were validated using Ansys finite element analysis software. LS-Dyna software is being used for validating the dynamic impact test results, and analyzing grid geometry variations for optimizing energy absorption. This study will lead to recommendations on the design and use in applications where impact energy absorption is important such as side doors of automobiles.