Full feed-in, also referred to as full export, describes an operating model for PV systems in which all generated electrical energy—apart from the system’s technical auxiliary consumption—is intended for export to the public grid. Electricity consumed at the site is supplied separately from the grid.
Full Feed-In at a Glance
- The generated PV energy—after deducting technical auxiliary consumption and any losses or curtailment—is intended entirely for export at the designated grid connection point.
- The system operator receives compensation for the exported energy or revenue from market-based electricity sales.
- A revenue-grade metering device records the exported energy at the defined settlement metering point.
- Unlike surplus feed-in, the PV system is not primarily used to supply local loads.
How Does Full Feed-In Work?
The PV modules generate direct current, which the inverter converts into grid-compliant alternating current. The electrical energy is then transferred to the public grid through a defined grid connection point. A revenue-grade metering device records the exported energy at the specified settlement metering point.
Electricity consumed by the building or business is supplied separately from the grid and measured at the designated import metering point. The precise arrangement of meters and electrical connection points depends on the applicable metering concept, the grid operator’s requirements, and the selected compensation or market-based sales model.
A full feed-in system may also temporarily import electrical energy from the grid. Inverters, data loggers, monitoring systems, transformers, and other auxiliary equipment may require energy when the PV system produces little or no power. This technical auxiliary consumption must be distinguished from the electricity consumed by other loads at the site and must be considered in the metering concept.
The exported energy recorded at the settlement metering point may differ from the generation measured directly at the inverters. Possible reasons include cable and conversion losses, technical auxiliary consumption, curtailment, and differences between the measuring devices used.
Where Is Full Feed-In Used?
Full feed-in is commonly used for PV systems whose primary purpose is to generate and sell solar electricity. Examples include ground-mounted PV plants, large rooftop systems without significant local consumption, and installations where generation and consumption are treated separately for technical or contractual purposes.
Full feed-in may also be selected at sites with their own electricity consumption. The decisive factor is whether exporting all generated energy is more suitable than surplus feed-in with self-consumption under the applicable technical, economic, and contractual conditions.
Benefits, Limitations, and Technical Requirements
Full feed-in enables the exported energy to be clearly allocated for metering and commercial settlement. The PV system’s operating strategy does not have to be aligned with the local load profile. However, whether the model is economically advantageous depends on factors including compensation or market revenues, grid electricity prices, the load profile, system size, and the applicable tax framework.
The main technical requirements include a suitable grid connection, an agreed metering concept, and revenue-grade metering. Depending on the market, grid operator, system size, and sales model, additional technical functions may be required.
Monitoring is used to supervise generation, export, availability, and system conditions. A plant controller, by contrast, implements technical requirements at the grid connection point. An interface to an electricity trader, aggregator, or market representative transfers market, power, or dispatch signals between the plant and the relevant market participant. These functions perform different tasks and are not generally interchangeable. An EMS or monitoring system therefore does not automatically replace a plant controller required under the applicable grid connection rules.
Implementation with EcoPhi
EcoPhi can collect and visualize PV generation, grid export, system availability, and relevant operating conditions. Comparing inverter data, meter readings, and, where available, solar irradiance data can help identify yield deviations and investigate potential technical losses. Alarms can be triggered in response to outages, communication failures, or unusually low export power.
Active self-consumption optimization is normally unnecessary for a pure full feed-in system. Depending on the project, EcoPhi can also exchange data with external systems or market participants. The specific implementation depends on the available device interfaces, the metering concept, and the technical requirements. EcoPhi should not be considered a general replacement for a required plant controller or an electricity trader, aggregator, or other market participant.
Conclusion: When Is Full Feed-In Suitable?
With full feed-in, PV generation is intended for export to the public grid. The model enables the exported energy to be clearly allocated but requires an appropriate metering concept. Its economic viability depends on compensation and market conditions as well as the potential benefits of using the electricity for self-consumption instead.
Frequently Asked Questions About Full Feed-In
What is the difference between full feed-in and surplus feed-in?
With full feed-in, all PV generation—apart from the system’s technical auxiliary consumption—is intended for export to the public grid. With surplus feed-in, the PV system first supplies local loads. Only the remaining energy is exported.
Does a full feed-in system have technical auxiliary consumption?
Yes. Inverters, monitoring devices, and auxiliary equipment may require electrical energy for their own operation. This technical auxiliary consumption is not the same as the general electricity consumption of the site.
Is full feed-in more economical than self-consumption?
There is no universal answer. Relevant factors include compensation or market revenues, grid electricity prices, the load profile, system size, and the applicable tax framework.
Does a full feed-in system require an EMS?
An EMS is not normally required for self-consumption optimization in a pure full feed-in system. Monitoring, export control, or technical communication with external systems may nevertheless be necessary or useful.