A renewable energy hybrid power plant, fed by photovoltaic (PV), and fuel cell (FC) sources with a supercapacitor storage device is proposed herein. The PV is used as the main generators; the FC acts as a power source, feeding only the insufficiency power (steady-state) from the PV; and the supercapacitor functions as an auxiliary source for supplying the deficiency power (transient and steady-state) from the PV and the FC. 4-phase parallel boost converters are implemented for the FC converter and the PV converter. These converters are linked to a Low-Voltage DC bus (60 V), which is connected to a High-Voltage DC Bus (200 V) by a Dual Active Bridge converter. A supercapacitor is also connected to a High-Voltage DC bus by a Dual Active Bridge converter. A mathematical model (reduced-order model) of the FC, PV, and supercapacitor converters is described for the control of the power plant. Using the nonlinear approach based on the flatness property, we propose a simple solution to the dynamic optimization, stabilization, and robustness problems in the hybrid power system. This is the key innovative contribution of this research project. The prototype small-scale power plant studied was composed of a PEMFC system (1.2 kW), a PV array (0.8 kW), and a supercapacitor module (100 F). Experimental results authenticate the excellent control algorithm during load cycles. The outputs from this research project are as follows. Three (3) research papers were published in international journals (ISI Web of Science) and two (2) technical papers were presented in international conferences (in Scopus). For human resource development, one (1) master degree student was graduated under the support of this project.