There is a growing number of producers of solar power in Switzerland. But unlike the electricity generated by hydropower plants, the production of photovoltaic plants is not controlled. This is becoming an increasing challenge for grid stability, as electricity generation and consumption must always be balanced. The volume of electricity transported via the grid is the determining factor for maintaining this balance. Consequently, power plant operators connected to the transmission system, as well as distribution system operators, must notify Swissgrid via their balance group how much electricity they will transport via the grid.
Balance group schedules as a basis for planning grid operations
These operators also prepare production forecasts using weather and historical data from electricity meters. They use these forecasts to feed the schedules of the balance groups. These schedules correspond to the planned feed-in and feed-out volumes of electrical energy for a specific period. Swissgrid bases its grid operation planning on this information and works on the planning until all the parameters are in the green zone. Swissgrid compensates for deviations in real-time operation with control power. This is a reserve for feeding electricity into the grid or removing it, depending on the situation.
Stable grid operation is becoming increasingly challenging
In the spring and summer of 2024, ensuring stable grid operation became increasingly challenging due to discrepancies between forecasted and actual photovoltaic feed-in volumes. The number of cases of this kind has been rising rapidly since the summer of 2023. This resulted in several instances when fluctuations in the grid could not be balanced out with control energy or power reserves. The ensuing additional costs had to be passed on to electricity consumers.
The quality of forecasts and data must be as accurate as possible
The real problem is not renewable energies or photovoltaic plants, but the quality of forecasts and data. The older the forecasts, the greater the risk of deviations between the balance group schedules and real-time operation. This is a major problem. Swissgrid only receives limited meter data from lower grid levels and has no control over its quality. To keep the forecasts up to date, a relatively simple improvement would be to update them also on weekends and public holidays, for example.
All the players in the electricity sector must contribute
As well as improving the quality of forecasts and data, other sustainable solutions must be found. Improvements are needed in terms of demand management, the controllability of plants and balancing in cooperation with Europe. This concerns all the players in the electricity sector. Whenever possible, Swissgrid adopts solutions involving innovation and digitalisation and works with partners in the industry to improve the availability of data regarding the photovoltaic energy being fed into the grid.
Improving the internal data basis for feeding photovoltaic energy into the grid
For this reason, Swissgrid launched a project in 2023 to significantly improve the internal data basis for feeding photovoltaic energy into the grid. The aim is to produce forecasts with a high regional and temporal resolution based on publicly available data on the photovoltaic plants installed in Switzerland. These forecasts will be made available internally via the Swissgrid data platform. The data can be used for various purposes, for example to better assess the impact of the photovoltaic feed-in on load flows and balancing. This will create direct added value for system operation.
The aim is to produce forecasts with a high regional and temporal resolution based on publicly available data on the photovoltaic plants installed in Switzerland.
An electricity agreement with Europe would provide a remedy
Deviations between generation and consumption have been successfully resolved thanks to cross-border cooperation with the transmission system operators in neighbouring countries. This illustrates once again the importance of cooperation with Europe to ensure the secure and stable operation of the Swiss extra-high-voltage grid. An electricity agreement with Europe would create the necessary legal certainty to enable Swissgrid to conserve direct access to a larger market for control power. All of this would substantially increase security with regard to stable grid operation in critical situations.
Author
