A distinction must be made here between active and reactive power:
If the grid operator specifies an active power specification at the point of interconnection, this always refers to the measurement at the point of interconnection. Therefore, for pure feed-in systems, the operating mode "open-loop control" (without feedback of the actual value) is sufficient. For systems with self-consumption, the opera-ting mode "closed-loop control" (with feedback of the actual value) should be used, since this converts excess PV energy into self-consumption and the power value at the point of interconnection still meets the grid operator's specification.
In pure feed-in systems and also in systems with self-consumption, the operating mode "closed-loop control" (with feedback of the measured values from the point of interconnection) should be selected. This way, the Data Manager accounts for and controls the influences of the line and, if applicable, of the transformer.
In systems with high self-consumption and a high reactive power demand (e.g., operation of electrical machines in commercial and industrial plants without an additional compensation system), the PV inverters might not be able to control the setpoints at the point of interconnection (reactive power value, cos phi value). For example, this can be operation of electrical machines in commercial and industrial plants without additional compensation equipment. In such systems, the PV inverters will generate almost only reactive power and hardly any active power. In such cases, the "open-loop control" operating mode is recommended. Contact your local grid operator.