Integration of small PV systems into the electricity market

A study commissioned by the Federal Environment Agency examines how small rooftop photovoltaic systems react to negative electricity prices and what role flexibility will play in the future.

The Solar Peak Act has set the course for reducing negative prices. It now makes sense to simplify the processes involved in direct marketing and to focus on the market integration of new consumers. This is the conclusion of a study conducted by the Öko-Institut and the Stiftung Umweltenergierecht on behalf of the Federal Environment Agency. According to the study, the number of negative electricity prices is likely to fall in the long term with increasing flexibility.

The study focuses on the question of how the operation of small rooftop systems can be made more market-oriented, particularly against the backdrop of frequent negative electricity prices during periods of high solar power generation. The central basis is the Solar Peak Act, which has been in force since February 2025. Since then, many newly installed systems no longer receive subsidies when electricity prices are negative. This affects not only directly marketed systems with a capacity of over 100 kW, but also new systems with a capacity of 7 kW following the installation of a smart metering system.

The analysis shows clear differences in the response behavior of the systems:
Directly marketed photovoltaic systems react most strongly to price signals by reducing or postponing their feed-in when prices are negative. Plants in the feed-in tariff with an intelligent metering system do not receive any remuneration when prices are negative, but can shift feed-in volumes to times of positive prices through self-consumption or battery storage. In contrast, existing plants without an intelligent metering system and subsidized plants remain largely inflexible.

Sufficient expansion of flexibility required

Despite a further increase in installed photovoltaic capacity, the authors expect a decline in negative electricity prices in the long term. The prerequisite for this is a sufficient expansion of flexibility on the demand side, for example through battery storage, controllable loads, electromobility or heat pumps. Modelling shows that generation peaks can increasingly be absorbed by flexible consumption in the future without requiring a complete market response from all photovoltaic systems.

The study identifies the consistent use of market signals on the consumption side, for example through dynamic electricity tariffs, as a key field of action. The decisive factor for system stability is less the curtailment of small rooftop systems and more a growing flexible electricity consumption that can absorb high feed-in peaks.

The short report "Marktintegration kleiner Photovoltaik-Dachanlagen. Between negative electricity prices and flexibility" is available on the website of the Federal Environment Agency.

Author: Katia Meyer-Tiedn