The Internet of Things (IoT) is gaining greater effect in our life from day to day. Wireless sensor networks (WSN) are embedded into the "Internet of Things" and power saving is one of the problems that it faces. This study introduces a new circuit design for a DC-DC Buck-Boost converter for controlling the output voltage of Energy Harvester (EH) via adaptive Neuro-Fuzzy inference systems (ANFIS) controller. It has proven that there is an effective changes regarding settling time almost being zero, overshoot being negligible and steady state voltage. As an application for the proposed design, an implementation for Precision Agriculture (PA) self-sustainable Wireless Sensor-Node (WS-N) with low power consumption has been presented. A solar power management for Precision agricultural in internet of things system proved to enhance cost-efficiency and increased lifetime for the device. The simulation results are determined by means that of MATLAB/Simulink software. The cloud service of Blynk IoT has been implemented to monitor the collected data on real time. Data on solar cells, batteries and soil were regarded reliable and precise.