Time-Shifted PV Feed-In – Between Regulation and Return

Energy supply is becoming an increasingly strategic topic for businesses – one reason why photovoltaic systems are booming in the commercial and industrial sector. In times of rising electricity prices, ambitious climate targets, and technical innovations such as battery storage, the time-shifted feed-in of solar power is gaining ever more importance. But just how economically attractive is this model really – and which regulatory hurdles must be overcome?

Status Quo of EEG Remuneration

Under the EEG 2023, the financing of larger PV systems takes place via the market premium model (Section 20 EEG). Here, the electricity generated is marketed directly on the spot market. The difference between the exchange revenue and the statutory so-called “value to be applied” is offset by the market premium. Settlement is carried out in 15-minute intervals by the transmission system operators.

For systems on buildings or noise barriers, an additional building bonus applies if the system is installed entirely on or against a building (Section 48 EEG). In the case of partial feed-in – i.e. when part of the electricity is self-consumed and the rest is fed into the grid – the following values to be applied apply (as of July 2025) (Bundesnetzagentur):

These values relate to the case of market premium marketing with the building bonus. The actual revenues are therefore made up of the respective Marktwert Solar plus the individual market premium. The monthly determined “Marktwert Solar” reflects the average revenues on the electricity exchange achieved through the direct marketing of solar power subsidized under the market premium model.

For commercial or industrial PV projects, this means: the larger the system, the lower the remuneration rate – which, however, can often be economically offset by higher self-consumption shares, storage integration, and the avoidance of electricity prices through self-supply.

Exclusivity Principle, Delineation Option, Exclusivity Option – and What Applies to Reverse Feed-In

Exclusivity Principle (Section 3 No. 1 EEG)

A central element of the EEG framework is the so-called exclusivity principle (Section 3 No. 1 EEG). It stipulates: only if electricity originates exclusively from a renewable energy installation does it qualify as eligible EEG electricity. For operators of photovoltaic systems with battery storage, this means specifically: only if the storage is charged exclusively with PV electricity does the stored and later fed-in electricity remain eligible for subsidy – for example within the framework of the market premium under direct marketing.

As soon as the storage is charged even partially with grid electricity (“grey electricity”), this remuneration entitlement lapses. The stored electricity loses its “EEG status” and is treated like conventional electricity – without subsidy, but with levies. Grid fees, electricity tax, and other surcharges may apply.

Delineation Option (Section 19 (3b) EEG)

To address this risk, the legislator created the delineation option. Through a technical metering concept – for example with separate meters – operators can prove seamlessly which share of the electricity in the storage comes from their own PV generation. This cleanly delineated share remains recognized as EEG electricity despite later feed-in and can be remunerated with the market premium. The delineation is thus a technical solution to effectively “save” the exclusivity principle, even when the storage also uses other sources.

⚠️ Important: the metering must be precise and legally compliant. Without reliable evidence, the remuneration entitlement for the entire stored electricity lapses.

Technically required are precise balancing group management and active participation in direct marketing. Storage systems must be integrated via remote controllability, forecast values, and market value reporting in accordance with Section 9 EEG. Metering concepts require smart meters that distinguish exactly between PV, grid, and storage electricity.

Legally, the topic remains complex: the delineation option can only be used successfully if the operator proves seamlessly and in a metrologically flawless manner which share of the stored electricity originates exclusively from their own EEG installation. If this proof is not unambiguous – for example due to a metering error or unclear allocation – the entire stored electricity is deemed ineligible for subsidy. In this case, the entitlement to the market premium or feed-in tariff lapses for the entire storage content, even if a proportion of PV electricity was actually stored.

Exclusivity Option

The exclusivity option is another way to fulfill the exclusivity principle – a kind of regulatory shortcut: the storage is operated exclusively with PV electricity by design. This can be achieved, for example, through physical separation, programmed control, or the deliberate avoidance of grid charging. In this case, no technical delineation needs to be carried out – the storage is systemically deemed EEG-compliant. This means: it is sufficient for the operator to credibly assure the grid operator and the Bundesnetzagentur that the storage is operated exclusively with PV electricity.

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

The Future of EEG Remuneration

The discussion so far assumes that one opts for a fixed EEG remuneration. However, this is not strictly necessary. EEG remuneration is continuously declining, especially for larger systems, and its future is uncertain. For operators, this means: the later the commissioning, the lower the guaranteed remuneration rate. That is why marketing outside the EEG – for example through PPAs, participation in the balancing energy market, or self-consumption – is becoming increasingly attractive.

Feed-In Without EEG Remuneration

If EEG remuneration is waived, the PV surplus is marketed directly on the electricity market at the current exchange electricity price. This price is volatile and, in times of high solar irradiation (large PV surplus), is often below the previous guaranteed remuneration rates. In this constellation, a battery storage system can help to shift the feed-in in time. As a result, electricity can be delivered during phases with higher market prices, which increases revenues and reduces dependence on momentary price peaks on the electricity market. At the same time, dropping EEG remuneration enables more flexible operation of the storage: grid electricity could also be usefully stored temporarily – for example during negative exchange prices – which makes additional use cases economically viable.

Conclusion

The combination of declining EEG remuneration and growing market volatility is increasingly shifting the focus toward flexible direct marketing. Battery storage plays a central role here: it not only enables the time-shifted feed-in of PV electricity at better market prices, but also opens up new fields of application beyond the EEG logic. Those who take regulatory requirements into account can use storage in the future as a strategic marketing instrument – both for economic optimization and for system-supportive grid integration.

Sources:

• EEG subsidy rates and market premiums (Bundesnetzagentur) swlandau.de+4Bundesnetzagentur+4geb-info.de+4

• Delineation and exclusivity principle (EEG Sections 3, 19)

• Marktwert Solar, grid fees, grid design