Staggered PV feed-in – between regulation and yield

For companies, energy supply is becoming an increasingly strategic issue - one reason why photovoltaic systems are booming in the commercial and industrial sector. In times of rising electricity prices, ambitious climate goals, and technological innovations such as battery storage, the deferred feeding of solar power is becoming increasingly important. But how economically attractive is this model really – and what regulatory hurdles need to be overcome?

Status quo of the EEG remuneration

According to the EEG 2023, the financing of larger PV systems is conducted through the market premium model (§ 20 EEG). Here, the generated electricity is marketed directly on the spot market. The difference between the stock market revenue and the legally defined so-called "feed-in value" is compensated by the market premium. Billing occurs at 15-minute intervals by the transmission system operators.

For systems on buildings or noise barriers, an additional building bonus applies if the system is completely installed on or at a building (§ 48 EEG). In the case of partial feeding – that is, when part of the electricity is consumed by the owner and the remainder is fed into the grid – the following feed-in values apply (as of July 2025) (Federal Network Agency):

These values refer to the case of market premium marketing with a building bonus. The actual revenues consist of the respective market value of solar plus the individual market premium. The monthly determined "market value of solar" reflects the average revenues at the electricity exchange generated by the direct marketing of solar power supported under the market premium model.

For commercial or industrial PV projects, this means: The larger the system, the lower the remuneration rate – which can often be economically compensated by higher self-consumption shares, storage integration, and avoiding electricity costs from direct consumption.

Exclusivity principle, delimitation option, exclusivity option – and what applies to feed-in

Exclusivity principle (§ 3 No. 1 EEG)

A central component of the EEG regulatory framework is the so-called exclusivity principle (§ 3 No. 1 EEG). It states: Only if electricity comes exclusively from a renewable energy system is it considered eligible EEG electricity. For operators of photovoltaic systems with battery storage, this means: Only if the storage unit is exclusively charged with PV electricity, does the stored and later fed-in electricity remain eligible – for example, within the framework of the market premium in direct marketing.

As soon as the storage is charged even partially with grid electricity (“gray electricity”), this entitlement to remuneration is lost. The stored electricity loses its "EEG status" and is treated as conventional electricity – without support, but with levies. Grid fees, electricity taxes, and further levies may apply.

Delimitation option (§ 19 Abs. 3b EEG)

To address this risk, the legislator has created the delimitation option. Operators can use a technical measurement concept – for example, with separate meters – to reliably prove which proportion of the electricity in the storage comes from their own PV generation. This clearly defined share remains recognized as EEG electricity despite later feeding and can be compensated with the market premium. The delimitation is thus a technical solution to effectively "save" the exclusivity principle, even if the storage unit uses other sources as well.

⚠️ Important: The measurement must be precise and compliant with legal regulations. Without reliable evidence, the entitlement to remuneration for the entire storage electricity is lost.

Technically required are precise balance sheet management and active participation in direct marketing. Storage units must be integrated via remote control, forecast values, and market value reports according to § 9 EEG. Measurement concepts require smart meters that can accurately distinguish between PV, grid, and storage electricity.

Legally, the topic remains complex: The delimitation option can only be successfully utilized if the operator provides seamless and measurement-compliant evidence of which proportion of the stored electricity comes exclusively from their own EEG system. If this proof is not clear – for example, due to a measurement error or unclear assignment – the entire stored electricity is deemed ineligible for support. In this case, the entitlement to market premium or feed-in remuneration for the entire storage content is lost, even if PV electricity was actually stored in part.

Exclusivity option

The exclusivity option is another way to fulfill the exclusivity principle – a kind of regulatory shortcut: The storage is designed to be operated exclusively with PV electricity. This can occur, for example, through structural separation, programmed control, or intentional avoidance of grid feeding. In this case, no technical delimitation needs to be made – the storage is systemically considered EEG-compliant. This means: It is sufficient for the operator to credibly assure the grid operator and the Federal Network Agency that the storage is exclusively operated with PV electricity.

The exclusivity option is often attractive for smaller operators because it saves measuring and retrofitting efforts. In return, it significantly restricts the flexibility of storage operation.

Future of the EEG remuneration

The previous statements assume that one opts for a fixed EEG remuneration. However, this is not necessarily required. The EEG remuneration is continuously decreasing, especially for larger systems, and its future is uncertain. For operators, this means: The later the commissioning, the lower the guaranteed remuneration rate. Therefore, marketing outside the EEG – for example, through PPAs, participation in the ancillary services market, or self-consumption – is becoming increasingly attractive.

Feed-in without EEG remuneration

If the EEG remuneration is waived, the marketing of the PV surplus occurs directly on the electricity market at the current stock market electricity price. This price is volatile and often falls below the previously guaranteed remuneration rates during periods of high solar radiation (lots of PV surplus). A battery storage system can help in this situation to temporarily shift the feed-in. This allows electricity to be delivered during phases with higher market prices, increasing revenues and reducing dependence on momentary price spikes in the electricity market. At the same time, waiving the EEG remuneration provides a more flexible operation of the storage: Grid electricity could also be meaningfully stored during negative stock market prices, opening up additional economically feasible application cases.

Conclusion

The combination of declining EEG remuneration and increasing market volatility is shifting the focus increasingly toward flexible direct marketing. Battery storage plays a central role: It not only enables the deferred feeding of PV electricity at better market prices but also opens up new application fields beyond EEG logic. Those who consider regulatory requirements can utilize storage as a strategic marketing instrument in the future – both for economic optimization and for system-supporting grid integration.

Sources:

• EEG support rates and market premiums (Federal Network Agency) swlandau.de+4Bundesnetzagentur+4geb-info.de+4

• Delimitation and exclusivity principle (EEG §§3, 19)

• Market value of solar, grid fees, grid design