In order to meet the requirements of miniaturization for the MEMS wireless sensor nodes, the integrated photovoltaic (PV) micro power system with the energy buffer is introduced. According to the power characteristics of the MEMS wireless sensor nodes, the energy buffer management scheme is adopted, which the solar energy is stored under sleep state of the sensor node and energy buffer supply power for the sensor node under activated state. The output voltage of solar cells can be controlled within maximum power domain by designingSappropriate energy buffer. The solar cells have high output power and conversion efficiency. Thus, the using efficiency of the solar energy is improved and the area of the solar cells is effectively reduced by the energy buffer management scheme. In addition to, the devices of designing PV micro power system have preferable integrated processing compatibility on chip, and the PV micro power system have better operating stability.