We describe and validate a complete hardware/software environment for power consumption analysis of PCIe-based accelerators, using the Intel Xeon Phi co-processor as the target platform. Our environment is flexible and affordable—based on commodity instrumentation—and provides both accuracy and transparency for the user, which enables an easy instrumentation of existing codes from the power consumption perspective. We present empirical power traces for two well known scientific codes (LINPACK and libflame) that give insights not only on the benefits of the presented environment, but also on the power profile of the Intel Xeon Phi co-processor under different workloads.