The distribution grid: invisible and central to the energy transition

The expansion of renewable energy is visible everywhere. Across Switzerland, black-blue photovoltaic panels are gleaming on more and more roofs. At present, the expansion is mainly focused on decentralised solar production. In total, 30,046 PV systems were connected to BKW’s distribution grid at the end of 2024, representing a total installed capacity of 650 MW – or almost twice that of the Mühleberg nuclear power plant. The energy transition is therefore in full swing.

The distribution grid must evolve in step with the expansion of solar energy

But the energy transition cannot be achieved through the solar boom alone. Alongside electricity production, other challenges are also increasingly coming into focus, namely the conversion and expansion of the grid infrastructure. In addition to the transmission grid, the distribution grid must also be further developed and reinforced, because practically all PV systems, EV charging stations and heat pumps are connected to the distribution grid (see the graphic below for an overview of the grid levels). The lower grid levels are far more hidden than the electricity production facilities and the transmission grid. The power cables in neighbourhoods are often laid underground, while transformer stations and distribution cabinets are behind locked doors. Every day, we pass by the inconspicuous concrete cubes that stand in garages, next to bicycle parking spaces and at the roadside, escaping our attention. Yet they play a crucial role in the transformation of our electricity system.

The energy transition begins in the neighbourhood

The expansion of PV systems is changing the flow of electricity in the power grid. Unlike in the old world of energy, electricity no longer flows only from central power plants to consumers, but also back again. Together with increased electricity consumption by heat pumps and EV charging stations, PV systems mean that the power grid has to transport higher power flows. This is why extensive expansion and conversion is already necessary today at all grid levels, from the power grid in the neighbourhood and the high-voltage grid through to the large transmission grid. ‘While the approval procedures for production facilities are being accelerated, this is not the case for the power grid,’ explains Andreas Ebner, Head of Grid Planning and Projects at BKW. This can mean, for example, that a PV system is approved, but the grid reinforcement or transformer station required to transport the energy is not. In the worst case, this makes it impossible to connect this and other photovoltaic systems in the neighbourhood in question.

The energy transition requires new transformer stations and lines

The Swiss Federal Office of Energy expects annual investments in the electricity grid to increase by 70 percent (SFOE Distribution Grid Study 2022). According to BKW’s analyses based on its own grid data, the largest share of the necessary investments in its grid will be in the (rural) medium- and low-voltage grid. Existing transformer stations will have to be upgraded, additional ones built and integrated into the existing electricity grid by means of lines. This is not only a financial challenge, but above all also a spatial planning and administrative one. Although the transformer stations are relatively small, at around 10 square metres each, they have to be built where electricity is distributed and consumed or produced. Finding locations and routing lines is becoming increasingly difficult. The permits for the necessary connection to the electricity grid are also time-consuming.

Transformer stations are the heart of the local electricity grid. They transform the voltage, contain a large connector strip to which several cables are connected, and include fuse elements. Transformer stations are needed to safely distribute electricity from various sources to individual households. For physical reasons, the supply radius of transformer stations is limited. This means that they have to be built close to consumers and producers. The more PV systems, heat pumps and EV charging stations are connected to the electricity grid, the more transformer stations are needed in order to absorb and distribute the electricity produced.

The grid express is heading in the right direction, but does not go far enough

Simplifying and accelerating the expansion of electricity grids is the aim of the revision of the Electricity Act. The dispatch on this so-called “grid express” was adopted by the Federal Council on 21 May 2025. BKW expressly supports the proposal and welcomes the planned acceleration in the transmission grid as an important and correct step. BKW also supports the new regulation for simplified site selection for transformer stations outside building zones and the accelerated resolution of differences in the planning approval procedure in the event of conflicting positions among authorities.

However, this is only a small part of the solution. In order for the proposed accelerations in grid expansion to have their full effect, the entire grid infrastructure must be taken into account. The lines between the transformer stations and the high-voltage grid are given too little consideration in the proposal. To achieve the energy transition, grid expansion must be driven forward with the same priority and consistency as the expansion of electricity production – and across all grid levels.

Statement on the amendment to the Electricity Act (acceleration of the expansion and conversion of the electricity grids)

Download

Statement on accelerating the expansion and conversion of electricity grids (amendment to the Ordinance on the planning approval procedure for electrical installations)

Download

News & Stories