The development of energy-efficient Power-to-Heat (PtH) technologies with high power density on a utility scale is a key element in the future of flexible energy systems. Although existing solutions for electric flow heaters (EFH) based on resistance heating have a high efficiency, the process outlet temperature and power output are limited by the lifetime of the contact heating elements. Inductively heated packed bed heaters can achieve higher gas outlet temperatures with a higher power density, which is essential for an efficient process. This paper focuses on the modeling, experimental validation and numerical analysis of inductively heated pebble bed gas heater. Foremost, a model that is based on a 3D finite volume method approach is introduced. After that, an experimental setup for different sphere arrangements is used to obtain results for concept verification and model validation. With the model validated, the design space for the PtH concept is investigated by varying the heat transfer area and material properties of the pebble bed. Design solutions with high energy efficiency above 90% and power density over 5.5 MW/m³ are presented for magnetic as well as non-magnetic materials at laboratory and utility scale.