In this article, an advanced nonlinear control scheme is proposed for a three-phase grid-connected inverter and a solar photovoltaic (PV) system connected dc-dc converter. The proposed control scheme is based on a nonlinear adaptive integral backstepping approach. The robustness of the proposed control scheme is achieved through maintaining stability of the overall system, extacting maximum power from the solar PV, and controlling active power. Moreover, the injection of less harmonic components into the grid, the superior performance against different atmospheric conditions, and external disturbances enduring capability are also key features of the controller. The stability of the overall system is achieved through the negative-definite control Lyapunov functions of the proposed control scheme. An adaptive law of the proposed control scheme on external disturbances provides the undergoing capability against the external disturbances. Maximum dc power from the solar PV system is obtained using the proposed control scheme on the dc-dc converter along with the incremental conductance algorithm. The proposed control scheme embedded in the three-phase grid-connected inverter with LCL-type filter provides maximum active power in the presence of external disturbances, controls reactive power, and injects less harmonic current into the grid. The simulation results under different atmospheric conditions further demonstrate the robustness of the proposed control scheme. The laboratory scale experiments validate the superiority of the proposed control scheme.