A method of determining an optimal operating speed of a variable speed genset is provided. The method may include determining whether an actual operating speed of the genset approximates a desired operating speed, the desired operating speed being predetermined based on a measured load value associated with the genset, the desired operating speed being associated with an applied offset value that is adjustable between a minimum offset value and a maximum offset value; incrementing the applied offset value of the desired operating speed to decrease the actual operating speed if the actual operating speed approximates the desired operating speed, and the applied offset value is less than the maximum offset value; and determining the desired operating speed as the optimal operating speed if the actual operating speed approximates the desired operating speed, and the applied offset value is equal to the maximum offset value.