The integration of renewable energies, especially photovoltaics (PV), poses new challenges for the Swiss electricity grid. The currently installed PV capacity is around 6 GW. By 2040, this is expected to increase to up to 30 GW. This development is leading to increasing imbalances in the Swiss control area, especially when PV production is high and consumption is low. In several cases since 2023, over 1 GW of balancing energy has had to be activated.

Swissgrid has launched the PV4Balancing pilot project to counter this trend in a structural manner. The aim is to develop a system service product that takes into account the special features of PV systems and taps into their potential for grid stabilization.

Objective and functioning of PV4Balancing

PV4Balancing is a new ancillary services pilot product designed to curtail PV plants as negative tertiary control power (TRL–). Unlike conventional TRL products, there is no obligation to maintain a fixed capacity at all times. Instead, standby bids are submitted based on the nominal capacity, whereby the actual PV production is reduced in the event of activation.

The data on current production is continuously transmitted to Swissgrid so that the available capacity can be estimated in real time. The reduction must take place within 12.5 minutes of activation. The product will be tested technically and organizationally as part of a one-year pilot. The test period runs from June 1, 2025, to June 1, 2026.

Participants in the pilot project will receive a fixed remuneration of 3 Swiss francs per megawatt hour of installed capacity for each hour of participation. Remuneration will be paid regardless of whether activation takes place.

Sample calculation: For a PV system with 1 MW of installed capacity, this results in: 1 MW * 3 CHF/MWh * 8760 hours = CHF 26,280 per year for pure provision.

In the event of activation, there is an additional market-based remuneration based on the tertiary control energy model. Remuneration is based on the pay-as-bid principle, with bids of up to CHF 15,000 per megawatt hour possible. With PV4Balancing, the usual compensation energy costs also apply in the event of activation, in line with existing TRL products.

Role of VGT in the pilot project

VGT is an active participant in the Swissgrid PV4Balancing working group and provides the technical integration and aggregation of controllable PV systems. The aim is to integrate smaller decentralized PV systems into the new ancillary services product via standardized interfaces and pooling mechanisms.

The connection is made via the VGT platform, which supports real-time data transmission, call-off logic, and balance group settlement. Customers with suitable PV systems can thus participate in the pilot project and tap into new revenue potential without having to significantly change their own consumption strategy or system operation.

Significance for the ancillary services market

PV4Balancing represents a structural advance for the integration of decentralized generation into the control energy market. It takes into account the volatile characteristics of PV systems and creates a defined process for their grid-friendly use. Following a successful pilot phase, the product is to be transferred to the regular ancillary services market from 2027.

The experience gained from the pilot project will be used to design processes, remuneration models, and technical requirements that are suitable for practical application. It is already evident today that grid-friendly curtailment of PV systems is being successfully practiced as a control service in other European countries. With PV4Balancing, Swissgrid is pursuing a similar approach that is tailored to the decentralized structure in Switzerland.

With PV4Balancing, Swissgrid is taking an innovative step toward the systematic integration of photovoltaic systems into the control energy market. The project combines grid stability with economic added value for operators and service providers. As a technical implementation partner, VGT is contributing to the successful piloting of the project and opening up access to a new market segment within ancillary services for its customers.

Sources

1. Swissgrid (2024): PV4Balancing product sheet – Curtailment of PV plants as a new ancillary service, internal document
2. Swissgrid (September 23, 2024): Kick-off PV4Balancing working group, presentation
3. Swissgrid (2024): Framework agreement for participation in the PV4Balancing pilot project, contract document
4. Swissgrid (2025): Blog post: The sun as a resource for stable grid operation, https://www.swissgrid.ch/de/home/newsroom/blog/2025/die-sonne-als-ressource-fuer-einen-stabilen-netzbetrieb.html