Today's advances in silicon integration density allow more and more functionality to fit into a system-on-chip (SoC). However, this has made power consumption the most critical design constraint for system-on-chips (SoCs). Power consumption especially affects portable devices as it influences battery lifetime. Moreover, specification, design and verification of System-on-Chips have become increasingly complex. In this work we present a novel methodology which supports specification and automates verification of power requirements through simulation and power estimation. We demonstrate our approach on an example SoC. Therefore, we specify power requirements for a higher class radio frequency identification (RFID) tag. Then we automatically generate test cases which allow to estimate the RFID tag's power consumption. To verify the power requirements we apply the test cases to the system model in simulation.