Local flexibility: Utrecht’s shared cars become batteries for the city

As solar panels spread across Europe’s cities, a new challenge is emerging: how can all that clean electricity be used when it is produced, without overwhelming already congested grids?

Utrecht is turning part of the answer into an everyday service. Its shared electric cars do more than moving people from one place to another. When parked, 50 of them can store locally produced solar power and return electricity to the grid when demand rises.

The bold result of this vehicle-to-grid equipped car sharing is more local grid flexibility—and a reminder that cities do not have to wait for grid reinforcement before taking action.

Making room for more solar

In Utrecht, panels have already been installed on around 35% of the city’s roofs. But rapid electrification and variable renewable production are putting increasing pressure on the regional electricity network. Instead of treating mobility and energy as separate challenges, the municipality helped bring together local company We Drive Solar, car-sharing operator MyWheels, Renault Group and grid operator Stedin.

Their Vehicle-to-Grid system charges shared electric cars when renewable electricity is abundant and demand is low. During busy periods, electricity stored in their batteries can flow back into the local grid. Bookings tell the system when each car will next be needed, ensuring that drivers still find it sufficiently charged.

In June 2025, the partners launched the first 50 bidirectional Renault 5 cars. The ambition is to expand the fleet to 500 vehicles, creating up to 5 MW of flexible capacity.

From promising experiment to public infrastructure

The launch was built on years of testing. Utrecht and its partners began exploring bidirectional charging more than a decade ago, followed by a pilot with Renault in 2019. This step-by-step approach matters. Utrecht did not wait for every technical and regulatory question to be settled. It used pilots to build evidence and test different solutions to avoid being dependent on a single manufacturer or technology. The city team, strongly backed by the Mayor, also established trust between public and private partners.

The model also creates value beyond the electricity system:

• Shared cars can replace privately owned vehicles,
• reduce pressure on public space and
• make electric mobility available without requiring every household to buy a car.

Three lessons for other municipalities

• Connect policy areas. Renewable energy, mobility and grid planning work better when addressed together.
• Work with the grid operator early. Local flexibility can ease immediate pressure even while network expansion continues.
• Design pilots for scale. Utrecht used real infrastructure and everyday user behaviour to turn an experiment into a practical urban service.

Utrecht shows that grid congestion need not bring local electrification to a halt. With the right partnerships, the batteries already arriving on city streets can help make space for even more homegrown energy.

Find the full Utrecht case study and more inspiring examples on the Homegrown Energy Campaign website.

This information campaign is ran by Energy Cities together with the EU Covenant of Mayors. Each month, we bring new stories and fresh angles on how local municipal teams manage to overcome concrete obstacles to create hyper-local, community-anchored energy services that create long-term benefits for the area.