Per-phase zero feed-in aims to ensure that no active power is exported to the public grid on any individual phase (L1, L2 or L3) at the grid connection point. Grid imports remain permitted: the objective is to avoid export on each phase, not necessarily to maintain a power flow of exactly 0 W.

Per-phase zero feed-in at a glance

• The power flow on each individual phase matters, not just the total across all three phases.
• Implementation requires measurements for each phase and a corresponding control strategy.
• With inverters that distribute power symmetrically, additional curtailment and simultaneous grid imports may occur.

How does it differ from net zero feed-in?

Net zero feed-in controls the sum of active power across all three phases. Individual phases may still export power while others import it.

Simplified example: L1 exports 2 kW, while L2 and L3 each import 1 kW. The total is 0 kW. This achieves net zero feed-in, but not per-phase zero feed-in.

For per-phase control, a three-phase meter at the grid connection point measures active power, including its direction, separately for each phase. The local controller adjusts photovoltaic output, battery charging or discharging, or suitable controllable loads accordingly. A total power measurement alone is insufficient.

When is per-phase export limitation useful?

It is used in photovoltaic and battery storage systems where export must be avoided on every individual phase, whether as an operating objective or a grid connection requirement. With unevenly distributed loads in particular, net zero feed-in control alone is insufficient.

What are the technical limitations?

Per-phase measurement does not automatically mean independent control of each phase. Many three-phase inverters distribute their output symmetrically. Without other balancing options, the phase with the lowest consumption then limits the permissible generation output. This can require additional curtailment while other phases continue importing power.

Inverters with asymmetric output control or individually controllable devices on each phase can make better use of the available flexibility. Their capabilities during grid-parallel operation are decisive; equivalent functions in backup mode alone do not demonstrate this capability.

Measurement delays and sudden load changes can cause brief periods of export. A small import margin on each phase and defined fallback strategies help limit these events. Permitted deviations depend on the applicable grid connection conditions.

How can EcoPhi support implementation?

EcoPhi can record and visualise per-phase measurements where the meters, interfaces and data points are supported. Active per-phase zero feed-in additionally requires suitable local control logic and controllable system components. Both capabilities must be confirmed for the specific EcoPhi configuration and connected devices. An existing net zero feed-in control function does not automatically provide per-phase zero feed-in.

The concept in brief

Per-phase zero feed-in addresses exports that can be hidden in the total across all three phases. How efficiently it can be implemented depends particularly on the controllability of the connected equipment.

Frequently asked questions

Is battery storage essential?

No. Suitable generation control with a sufficiently fast response can also implement this function.

Does per-phase zero feed-in mean energy independence?

No. The system remains connected to the grid and may import electricity on one or more phases.