From Feed-in Tariffs to System Integration: Why Rooftop Solar Needs a Managed Transition

Why small rooftop PV needs an orderly transition and why the technical tools already exist

The 2027 amendment of Germany's Renewable Energy Sources Act (EEG) raises the right question: how can photovoltaics contribute more effectively to a stable and flexible energy system? The answer, however, should not be an abrupt withdrawal of support for small rooftop installations. Instead, it should be a predictable transition toward greater storage deployment, controllability, and intelligent grid integration through energy management systems.

The debate surrounding the 2027 EEG reform should not be reduced to the question of whether small PV systems should continue exporting electricity to the grid. The key issue is how to manage the transition from a simple feed-in model toward a system-oriented prosumer model. A recent white paper by E3/DC (German language) provides an important technical foundation for this discussion. Its findings suggest that the current expansion of building-integrated photovoltaics has not led to widespread overloads in low-voltage distribution networks. Rather, the data points to manageable early indicators that require targeted responses: battery storage, intelligent control systems, energy management systems, controllable distribution transformers, and an accelerated rollout of smart metering infrastructure.

The central conclusion is therefore not that everything can continue as before. Rather, it is that further rooftop PV expansion remains technically feasible if generation, consumption, and grid operation are managed in a more integrated and intelligent way. This is precisely where the constructive link to the EEG reform lies. The direction is right if photovoltaics become increasingly linked to self-consumption, storage, flexibility, and system integration. What would be problematic, however, is a hard break in support mechanisms before the necessary technical and market prerequisites are widely available and ready for mass deployment.

The tools already exist — implementation is what matters
The regulatory framework for rooftop solar installations is essentially already in place. On the consumption side, § 14a of Germany's Energy Industry Act (EnWG) allows distribution system operators to manage flexible electrical loads such as EV charging points, heat pumps, and battery storage systems during periods of local grid congestion. This makes it possible to address local bottlenecks without fundamentally limiting the connection of new flexible loads.

On the generation side, § 9 of Germany's Renewable Energy Sources Act (EEG) establishes technical requirements for renewable energy installations, including controllability, real-time monitoring of feed-in, and export limitations where necessary. For rooftop PV systems, this means that the regulatory framework already contains mechanisms that can make electricity exports technically manageable when required by the grid.

The crucial issue is therefore not the creation of ever more intervention mechanisms, but rather the practical implementation of the instruments that already exist. Their effectiveness depends on one key condition: smart metering systems, control technologies, and standardized processes must actually be available. Without this rollout, system-oriented control in the small-scale PV segment remains partly theoretical.

Direct market participation for renewable electricity, dynamic feed-in models, and grid-supportive operation can only become mainstream if they are simple, reliable, and economically viable for prosumers, installers, grid operators, and market participants alike.

The EEG Reform needs the right sequence
The planned restructuring of the EEG should therefore not take the form of an abrupt disruption. The transition from the current model toward a system-oriented prosumer model is the right objective. But the sequence matters: first, the necessary system prerequisites must be established; only then should support mechanisms be gradually reduced.

For small rooftop systems, there is therefore a strong case for a simple, predictable, and gradually declining transitional remuneration scheme. Such an approach would preserve investment certainty while still enabling the necessary transformation of the energy system. At the same time, the rollout of smart meters, control units, battery integration, energy management systems, and scalable direct-marketing models should be accelerated consistently.

Such an approach would neither defend the status quo nor reject market integration. On the contrary, it would create a credible pathway toward greater market and system integration. Private investments in rooftop PV, home batteries, charging infrastructure, and energy management systems will only continue at scale if the economic framework remains understandable and predictable.

System integration yes — but without an investment shock
The target vision is clear: the next phase of the energy transition in buildings will not be based on simple electricity exports but on intelligent energy systems. Photovoltaics, battery storage, heat pumps, electric mobility, and energy management systems must work together as an integrated whole.

The good news is that the necessary technical building blocks already exist. The challenge lies in scaling them, standardizing them, and making them easy to implement in mass-market applications.

Precisely for this reason, the EEG reform should not force small rooftop systems into a market-based model through the abrupt elimination of feed-in remuneration when the necessary conditions are not yet available everywhere. Anyone seeking greater system integration must first build the bridge toward it: through smart metering and control technologies, clear regulatory frameworks, simple processes, and a transition pathway that does not discourage investment.

The message is therefore clear: system integration, yes — but not through an abrupt end to support mechanisms. Small PV systems need a predictable transition: a simple and gradually declining transitional remuneration scheme combined with a determined rollout of smart metering, controllability, storage integration, and scalable direct-marketing models.

In this way, the EEG reform can enable the transition from the old "produce and forget" model to a truly system-oriented prosumer model without unnecessarily undermining confidence in private rooftop PV investments. The transformation is technically achievable. It simply needs to happen in the right order.