In this paper, a complete control architecture is proposed for the voltage conditioning stage of a hybrid power generation system composed of a Stirling engine coupled with a supercapacitor. Such a solar energy-based generation system aims at providing electricity to off-grid regions. The novelty of the proposed architecture is that it completely handles constraints on all the state variables of the electric stage while providing near to optimal performances in terms of settling time. The derivation of the control law enables a deep understanding of the main issues involved in the success of the closed-loop control. Moreover, the resulting feedback laws are real-time compatible and are given in a complete explicit form. (C) 2014 Elsevier Ltd. All rights reserved.