Over recent years Koolen Industries and We Drive Solar have invested heavily in developing advanced charging infrastructure, including bidirectional charging. The Solar City charging post from We Drive Solar can now be found across the Netherlands and is already being used by several leading customers. In Europe’s largest bidirectional charging project, now starting in Utrecht, this charger plays a key role.
“We are directly helping to reduce grid congestion in Utrecht with our technology,” says Robin Berg, Director of We Drive Solar. For more than fifteen years he has been using solar power to charge electric cars. Along the way he realised that those cars could play a crucial role in relieving the overloaded electricity grid.
“In 2016 we signed an agreement with Renault Group in Paris to explore bidirectional charging. This led to the 2019 pilot with the Renault ZOE in the city of Utrecht. That pilot paved the way for the scale‑up phase, which starts now. Because the demand for charging stations that are fit for the future energy system is growing, we are working with Koolen Industries, the investment group of Kees Koolen. Development, production and delivery of bidirectional charging solutions takes place in Hengelo under the name We Drive Solar.”
Market for charging stations
The charging‑station market has developed enormously in recent years. For almost a decade We Drive Solar has been a front‑runner in smart charging solutions. The company supplies bidirectional charging posts suitable for:
- energy balancing
- solarguided charging
- discharging vehicles
The chargers are also ready for smart charging (power management) with a limited grid connection. Where solar panels are present, the available capacity can be supplemented in real time with locally generated solar power. This allows more cars to charge simultaneously and can generate additional revenue for the housing association/homeowner or the owner of the solar panels.
Solar City charger
The Solar City is a robust freestanding charger that provides the power and flexibility needed for larger charging demands. The post is designed for installation on a foundation and can charge two vehicles at the same time. It can also smart‑charge and balance the grid. Even in Utrecht’s historic city centre, the Solar City integrates seamlessly into the streetscape.
We Drive Solar also operates charging plazas beneath a Solar Carport, such as at insurance company a.s.r., CTpark Amsterdam City, the Jaarbeurs and Triodos Bank.
Full V2G Ecosystem
What makes this day unique is that it’s a full V2G ecosystem going live. On top of the integration of Mobilize V2G Toolkit with the We Drive Solar charger, a full V2G ecosystem is now in operation. We Drive Solar has developed an aggregation service based on the departure times of the shared cars and the hourly energy market prizes (EPEX). This means that MyWheels can actually make money as we are charging and discharging their cars; the grid congestion is lowered by discharging during peak hours, and renewable energy is being made available 24/7, allowing more renewables on the grid. This is now live on the 50 Renault 5 as of today.
Business case
There is a clear business case for the partners in these projects, as seen in the bidirectional ecosystem of Renault Group, We Drive Solar and MyWheels. Berg: “Solar energy is becoming available in ever‑greater quantities, and at the same time we need to relieve the grid because it is so congested. V2G technology is a smart and efficient solution. For at least ten years various parties have been trying to deploy the technology on a small scale, but no one has yet developed a scalable concept. Together with Renault Group we have now succeeded. Renault has integrated the technology into an affordable car and We Drive Solar has invested in a scalable charger.”
The partnership had to be financially attractive. The business case is compelling: because car sharing uses reservations, MyWheels knows exactly when a car needs to be fully charged. Charging and discharging can therefore be scheduled accurately. We Drive Solar has a dynamic energy contract for each charging post, so it is clear when electricity is cheap and cars should be charged. With plenty of wind overnight or sun during the day, electricity may cost only a few cents per kWh—or even be free. In the evening, when demand peaks, prices rise and feeding electricity back becomes attractive. The difference is the revenue model. For the grid operator Stedin this results in reduced congestion at peak times.
Grid congestion is urgent in Utrecht
The Utrecht region has one of the most overloaded power grids in the Netherlands. That is why the city was chosen to launch the car‑sharing service with EVs and V2G technology. The 500 electric Renault models operated by MyWheels can relieve grid congestion by 5 megawatts. The regional shortfall at peaks, however, is 250 megawatts—so fifty times as many EVs are needed. Berg: “Scaling up is essential now. Renault can build the cars in two months, and we can supply the charging posts within a few months. The congestion in the region could be solved within a year.”
“We have calculated that 1.5 million bidirectional EVs would be needed to power the whole of the Netherlands,” Berg says. “If you use solar and wind energy for that, we have a sustainable energy system and no longer need coal‑ or gas‑fired plants. EVs also serve as a buffer to relieve grid peaks, reducing pressure on grid operators who cannot reinforce the network everywhere at once—there is a shortage of money, people and materials. Network expansion will still be necessary, but large‑scale bidirectional charging eases the immediate pressure.”
University of Utrecht study: Shared cars cut grid congestion by 50%
Electric shared cars cause half as much grid congestion as privately owned electric cars. Car‑share users charge differently and avoid peak times. That is the conclusion of a 2020 study by Utrecht University: “The Impact of Transitioning to Shared Electric Vehicles on Grid Congestion and Management”.
More and more Dutch households are buying an electric car because they emit less CO₂ and particulate matter. The number of shared cars in the Netherlands has also grown sharply in recent years. Switching from private cars to shared EVs is sustainable because users drive less and fewer cars need to be produced.
Although the shift to electric mobility is crucial, charging EVs causes peaks in electricity demand. A large EV being charged can place the same load on the grid as several households. The more EVs there are, the greater the strain. That means grid operators must reinforce their networks, which raises social costs. If you can avoid these peaks, you can avoid the expense. Researchers at the Copernicus Institute of Sustainable Development at Utrecht University examined whether the transition to shared EVs has an effect on energy peaks when charging those cars. They used charging data from We Drive Solar’s shared EVs.
Current charging peaks occur on weekday evenings when EV drivers plug in after their trip, while households are using a lot of electricity for cooking, for example. The study shows that the peak falls by more than 50 % when a large share of residents switch to shared cars. Car‑share users are more inclined to choose other transport modes and drive fewer kilometres per car. Shared cars are also less often used for commuting, so fewer cars charge simultaneously when people arrive home from work.
Balancing with electric cars
The study advocates further integration of shared EVs to prevent grid problems and even contribute positively to a more stable electricity network. The time an EV needs to charge is usually much shorter than the time it is plugged in. Research is therefore under way into how EV batteries can be used by grid operators to balance the system—for example by feeding electricity back to the neighbourhood at peak times. The study shows that the potential to balance the grid is greater when a large share of residents switch to shared EVs. Using EVs as batteries on wheels is currently being examined in the Smart Solar Charging project.
TU Delft study: Charging pauses double smart-charging effectiveness
EVs are increasingly charged “smartly”, i.e. only at times when there is plenty of capacity on the grid and low electricity prices. Smart charging prevents overload and saves money. To make the most of smart charging you want not only to reduce charging speed during busy or expensive periods but also to pause charging altogether. Research from Utrecht University and TU Delft shows that adding charging pauses doubles the effectiveness of smart charging. Most cars already support this, but some models do not handle pauses well. The researchers call on car manufacturers to ensure that all models can cope. The standards exist but are not always applied correctly. Making technical smart‑charging requirements mandatory could help.
Fleet project by Stedin, businesses & academia
Grid congestion is a growing problem in the Netherlands. One solution is smart EV charging, with charging speed adjusted to grid load. In the FLEET collaboration project, network operator Stedin, different companies and research institutions began smart‑charging on 380 public posts in Utrecht a few years ago. Smart charging in this trial was based on flexible grid tariffs. This experimental price signal reduced EV peak load by 15 %, relieving the local grid. Users generally noticed nothing because their cars were plugged in longer than necessary and there was enough space to charge them outside the peak.
During the FLEET experiment customers could opt out of smart charging at the post. Although they had said they wanted this option, in practice it was rarely used. Surveys showed that most drivers noticed nothing when the charging was delayed and were generally happy to help relieve grid congestion.
Although the FLEET experiment has ended, smart charging continues at Utrecht’s public posts. Control of the chargers has been switched to grid‑aware charging, which is now being further studied. This method has been rolled out nationwide since 2023. In this system the available capacity for charging EVs varies during the day according to grid load.
