Due to size, longevity, safety, and recharging concerns, energy harvesting is becoming a better choice for many wearable embedded systems. However, harvested energy is intrinsically unstable. In order to overcome this drawback, nonvolatile processor (NVP) was proposed to bridge intermittent program execution. However, even with NVP, frequent power interruption will severely degrade system performance. In this paper, we will propose a multi-source energy harvesting system to combine multiple harvesting sources to provide a more stable power supply. Maximum power extraction and converter parameter optimization techniques will be discussed. Preliminary experimental results show the proposed architecture is very promising in providing a stable energy source for NVPs.