Several approaches are used at JET to achieve operation at high density with good energy connement. One of them is the injection of solid fuel pellets to realise ecient particle refueling by deposition deep inside the plasma column. The new pellet launch system capable of launching from the torus magnetic high field side was investigated for its capability to fulfil this task in conventional ELMy H-mode discharges. Optimised pellet scenarios were developed for plasma congurations with Ip = 2.5MA, Bt = 2.4T, averaged triangularity < du > 0.34 and mainly neutral beam heating at a level of approximately 17MW. The accessible operational range was extended by the pellet tool with respect to gas puff refueling. For example H-mode conditions could be maintained at densities beyond the Greenwald level. Plasma energy confinement was observed to become density independent at high densities. When avoiding confinement deterioration due to pellet triggered MHD activity or parasitic pellet born gas in appropriate pulse schedules, enhanced particle inventory with more peaked density profiles was achieved while maintaining the plasma pressure profile. First attempts indicate pellet advantages can be combined with the benefits achieved by higher triangularity. Very high particle refueling efficiencies were found for pellets injected into "ITER like" discharges with an upper triangularity < du > of 0.53.