Solar package I has new EEG options for large-scale storage created by replacing the previous Storage-related exclusivity principle was relaxed. This principle had been in place since the early days of the EEG and stipulated that an electricity storage system could only be charged with renewable electricity (e.g. from a PV system) if the stored electricity was to be used later. with EEG subsidy was to be fed into the grid. As soon as even a single kilowatt hour of "gray" grid electricity was fed into the storage system - for example by charging from the public grid - the entire contents of the storage system were no longer considered "green". As a result, the stored renewable electricity was no longer eligible for subsidies and there were no guarantees of origin for green electricity.
Restrictions due to the principle of exclusivity
In practice, this narrow interpretation of the exclusivity principle had far-reaching consequences for the economic use of battery storage systems. In particular, this applied to Large battery storage systems in combination with commercial photovoltaic systems. Operators were faced with the fundamental decision of either using their large storage systems for Optimization of the PV feed-in or for Other revenue models to be used. Simultaneous multiple use ("multi-use") was excluded.
In concrete terms, this meant that large storage units charged by the company's own PV electricity were used exclusively for internal storage. Peak shaving and load shifting. Stored surplus solar power could, for example, be fed back into the grid in the evening at higher exchange prices, including EEG subsidies. However, this only works if the PV system continuously produces large amounts of electricity. As soon as the green electricity is not sufficient for this in some winter months, the large-scale storage system has to be filled with gray electricity. However, it was precisely this grid feed-in that led to the Loss of the entire EEG subsidy entitlement - even if green electricity was previously stored.
New EEG options for large storage tanks after solar package I
The Solar Package I and the EEG 2025 have introduced new regulations for the use of electricity storage systems in conjunction with renewable energies. The aim was to Flexibility in the electricity system and integrate storage systems more strongly into the energy transition - without jeopardizing the funding logic of the EEG. For operators of PV systems with large-scale battery storage systems, there are now three clearly defined operating options for the intermediate storage of electricity, particularly for feeding into the public grid.
1. the new demarcation option: flexibility with metrological separation
For Large plants with large storage tanks and Energy management systems there is now the new Accrual option with direct marketing obligation. It allows the storage system to be charged with both renewable electricity and grid electricity - provided, however, that the respective amounts of electricity are clearly separated by measurement. On this basis, the proportion of the stored and fed-in energy that is actually eligible for subsidies is then calculated.
Example: If 70 % of a storage system is charged with solar power and 30 % with grid power over the course of the year, only the corresponding proportion of the grid feed-in (70 %) receives EEG funding.
This option offers Great flexibility for industrial and commercial companieswhich both the Increase photovoltaic self-consumption as well as grid or market-serving storage applications - for example as part of multi-use concepts. To this end, the Federal Network Agency defines the details for verification and balancing.
2. the exclusivity option: clear separation - full remuneration
The new storage-related exclusivity is now also an option. It essentially corresponds to the previous EEG regulation: the electricity storage system is charged exclusively with renewable electricity - and never with grid electricity. If this condition is met over the entire calendar year, the stored electricity is considered to be completely green. Feeding it into the grid is then rewarded with the full EEG remuneration.
This option is particularly suitable for operators who are looking for a technically clean and legally compliant solution, such as for home storage systems or smaller commercial installationsthat rely entirely on self-supply with renewable electricity. The advantage: no complex metering or billing system is required - as long as there is no grid supply, the subsidy entitlement remains fully intact.
3. the flat-rate option: simple & practical for small systems
For still Smaller PV systems with storage - specifically up to 30 kWp capacity - the Package option was created. This enables operators to take advantage of a simplified subsidy without having to implement a detailed metering concept. The prerequisite is that the storage system and PV system belong to the same operator (plug-in solar devices are excluded). The subsidy is granted on a flat-rate basis: it is assumed that 500 KW of eligible electricity per kilowatt of installed PV power flows from the storage system into the grid each year.
This regulation is clearly aimed at Private households or small commercial enterpriseswho want to benefit from the EEG subsidy as easily as possible without having to invest in expensive measurement technology. To this end, the electricity is billed via a direct marketer who can also directly include bidirectional charging.
Overview of EEG options for large-scale storage systems:
| Option | Origin of electricity | Scope of funding | Target group |
| Accrual option | EE + gray electricity | Proportionate EEG subsidy | Large-scale storage/industry |
| Exclusivity option | Only renewable electricity | 100 % of the infeed | Pure RE storage |
| Package option | EE + gray electricity | Fixed for 500 kWh | Home/small business |
More flexibility thanks to the new EEG options for large storage systems
The three newly introduced EEG options for feeding electricity from storage systems into the grid will remove a central stumbling block in the previous storage regulation. Large-scale battery storage systems in particular can now be used more economically and flexibly. The three new EEG options of the Solar package I now enable differentiated storage management. These range from purely green feed-in to pro rata support for mixed loading. This paves the way for multi-use concepts that can combine electricity marketing, grid efficiency and self-consumption - without risking the loss of EEG subsidies.
At the same time, simple subsidy models for smaller systems will be retained. Operators of large PV and storage systems will also continue to have the opportunity to have their projects subsidized under the Innovation tenders to market.