Abstract: Solar generators, fuel cells and similar d-c voltage sources have a current-voltage characteristic, on which at one point ("maximum power point" MPP) the maximum power can be taken from the d-c voltage source. In an arrangement, in which a d-c voltage source feeds a consumer through a controllable power converter, the optimum operating point is automatically set by setting a reference value for the voltage or the current into the converter, and impressing a supplemental reference value temporarily thereon as a disturbance variable at certain time intervals. If due to the impression, the output power of the d-c voltage source increases, the reference value is adjusted in the direction of the supplemental reference value. If, on the other hand, the sign of the power change is negative, the reference value is changed opposite to the sign of the supplemental reference value. After a finite number of reference value changes, the instantaneous operating point is this brought to the optimum operating point.