This paper presents a voltage control strategy based on the optimal duty cycle for a renewable energy system comprised of a Thermoelectric Generator (TEG) in cascade with the KY-Converter, a voltage-boosting topology, and coupled to a resistive load. The mathematical model that describes the TEG is presented as well as a derivation for optimal values (i.e. current and voltage) that provide maximum power. The equations for the KY-Converter are described, including the averaged equations in terms of the Duty Cycle using the switching transistors in the topology. The different steps to determine the appropriate TEG for a specific resistive load are provided for the transfer of near maximum power. Simulations are provided for a specific resistive load whose output voltage is regulated and controlled through the use of a KY-Converter for a TEG input.