imgGermany’s transition to renewable energy has markedly slowed down, the result of a new law last year that excludes larger systems from the feed-in tariff and levies surcharges on PV system owners who consume the electricity that their systems generate.Photo: Bernhard Lang/Getty Images

Among European countries, Germany is probably the best known worldwide for its Energiewende (“energy transition”), with good reason: Although it gets a smaller portion of its electricity from renewables than does Denmark, Portugal, or Spain, Germany generates more raw kilowatt-hours of electricity than any of those other countries do. What’s more, Germany has a far larger and more industrialized economy—the fourth largest in the world—and so its need for reliable power is greater. In 2014, wind, biomass, solar, and waste-to-energy plants met 24 percent of Germany’s electricity demand.

Most impressive has been Germany’s integration of more than 38 GW of solar PV, the largest solar capacity in the world, providing more than 6 percent of Germany’s electricity in 2014. A feed-in tariff enacted in 2000 simplified and streamlined the process for building solar and other renewable energy projects, connecting them to the grid, and selling power to the local utility at a fixed rate. This policy led to a rapid growth of solar and established a model that has been adopted by many other countries. The German power grid’s robust interconnections to the wider European grid also made the transition to renewables easier than in, say, Spain or Portugal. And in general, the German government’s support for renewables has been more stable and less susceptible to political whim than elsewhere.

graphic link to Europe's Road to Renewables article

However, the Energiewende has had some missteps. Even as Germany’s solar capacity was rapidly expanding, the country’s existing interconnection standards required that distributed generation facilities, including solar PV installations, automatically disconnect from the bulk grid if system frequency exceeded 50.2 hertz—a situation that can occur when power supply exceeds demand. Solar sometimes provides more than 40 percent of the country’s electricity needs at midday, so this standard could have resulted in vast amounts of PV capacity going off-line all at once.

As a remedy, Germany began requiring new frequency settings for all PV systems in 2012. This meant retrofitting at least 315,000 existing installations with smart inverters capable of automatically reducing power output during periods of overfrequency, at an estimated cost of 65 million to 170 million euros. As of August 2014, roughly half of these retrofits had been completed.

Germany must also deal with constraints with its own transmission grid. The current plan is to install up to 30 GW of wind capacity by 2020 in the northern half of the country, but getting this electricity to population centers to the south will require new transmission infrastructure.

Clouding the picture further, the new coalition government elected in 2013 has been more hostile toward renewable energy than its predecessors. Last August, a new German law put forward by Energy and Economics Minister Sigmar Gabriel took effect. Among other things, it excludes larger renewable energy systems from the feed-in tariff and levies surcharges on PV system owners who consume the electricity that their systems generate. This immediately reduced the rate of adoption of renewable energy, with new PV deployments falling from 3.3 GW in 2013 to under 2 GW in 2014. And so, while the Energiewende is not over, it has greatly slowed down.

About the Authors

Christian Roselund (@croselund) is the global content director for SolarPV TV. He previously covered the global solar industry for the trade publications pv magazine and SolarServer. John Bernhardt (@bernzzi) is the outreach and communications director for the Clean Coalition.

To Probe Further

For statistics on solar- and wind-generated electricity in Germany in 2014, see the PowerPoint slides [pdf] by Bruno Burger of the Fraunhofer Institute for Solar Energy Systems. For a more complete breakdown of Germany’s renewable energy sector over the last 25 years, see this table (in German) by the Working Group on Energy Balances.

For a discussion of Germany’s retrofitting of its solar PV inverters, see the executive summary of “Impact of Large-scale Distributed Generation on Network Stability During Over-Frequency Events & Development of Mitigation Measures” [pdf], by engineers at the University of Stuttgart’s Institute of Combustion and Power Plant Technology and the consulting firm Ecofys.

The Conversation (0)
This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

Hundreds of charging stations for electric vehicles dot Utrecht’s urban landscape in the Netherlands like little electric mushrooms. Unlike those you may have grown accustomed to seeing, many of these stations don’t just charge electric cars—they can also send power from vehicle batteries to the local utility grid for use by homes and businesses.

Debates over the feasibility and value of such vehicle-to-grid technology go back decades. Those arguments are not yet settled. But big automakers like Volkswagen, Nissan, and Hyundai have moved to produce the kinds of cars that can use such bidirectional chargers—alongside similar vehicle-to-home technology, whereby your car can power your house, say, during a blackout, as promoted by Ford with its new F-150 Lightning. Given the rapid uptake of electric vehicles, many people are thinking hard about how to make the best use of all that rolling battery power.

The number of charging stations in Utrecht has risen sharply over the past decade.

“People are buying more and more electric cars,” says Eerenberg, the alderman. City officials noticed a surge in such purchases in recent years, only to hear complaints from Utrechters that they then had to go through a long application process to have a charger installed where they could use it. Eerenberg, a computer scientist by training, is still working to unwind these knots. He realizes that the city has to go faster if it is to meet the Dutch government’s mandate for all new cars to be zero-emission in eight years.

The amount of energy being used to charge EVs in Utrecht has skyrocketed in recent years.

Although similar mandates to put more zero-emission vehicles on the road in New York and California failed in the past, the pressure for vehicle electrification is higher now. And Utrecht city officials want to get ahead of demand for greener transportation solutions. This is a city that just built a central underground parking garage for 12,500 bicycles and spent years digging up a freeway that ran through the center of town, replacing it with a canal in the name of clean air and healthy urban living.

A driving force in shaping these changes is Matthijs Kok, the city’s energy-transition manager. He took me on a tour—by bicycle, naturally—of Utrecht’s new green infrastructure, pointing to some recent additions, like a stationary battery designed to store solar energy from the many panels slated for installation at a local public housing development.

This map of Utrecht shows the city’s EV-charging infrastructure. Orange dots are the locations of existing charging stations; red dots denote charging stations under development. Green dots are possible sites for future charging stations.

“This is why we all do it,” Kok says, stepping away from his propped-up bike and pointing to a brick shed that houses a 400-kilowatt transformer. These transformers are the final link in the chain that runs from the power-generating plant to high-tension wires to medium-voltage substations to low-voltage transformers to people’s kitchens.

There are thousands of these transformers in a typical city. But if too many electric cars in one area need charging, transformers like this can easily become overloaded. Bidirectional charging promises to ease such problems.

Kok works with others in city government to compile data and create maps, dividing the city into neighborhoods. Each one is annotated with data on population, types of households, vehicles, and other data. Together with a contracted data-science group, and with input from ordinary citizens, they developed a policy-driven algorithm to help pick the best locations for new charging stations. The city also included incentives for deploying bidirectional chargers in its 10-year contracts with vehicle charge-station operators. So, in these chargers went.

Experts expect bidirectional charging to work particularly well for vehicles that are part of a fleet whose movements are predictable. In such cases, an operator can readily program when to charge and discharge a car’s battery.

We Drive Solar earns credit by sending battery power from its fleet to the local grid during times of peak demand and charges the cars’ batteries back up during off-peak hours. If it does that well, drivers don’t lose any range they might need when they pick up their cars. And these daily energy trades help to keep prices down for subscribers.

Encouraging car-sharing schemes like We Drive Solar appeals to Utrecht officials because of the struggle with parking—a chronic ailment common to most growing cities. A huge construction site near the Utrecht city center will soon add 10,000 new apartments. Additional housing is welcome, but 10,000 additional cars would not be. Planners want the ratio to be more like one car for every 10 households—and the amount of dedicated public parking in the new neighborhoods will reflect that goal.

This photograph shows four parked vehicles, each with the words \u201cWe Drive Solar\u201d prominently displayed, and each plugged into a charge point.Some of the cars available from We Drive Solar, including these Hyundai Ioniq 5s, are capable of bidirectional charging.We Drive Solar

Projections for the large-scale electrification of transportation in Europe are daunting. According to a Eurelectric/Deloitte report, there could be 50 million to 70 million electric vehicles in Europe by 2030, requiring several million new charging points, bidirectional or otherwise. Power-distribution grids will need hundreds of billions of euros in investment to support these new stations.

The morning before Eerenberg sat down with me at city hall to explain Utrecht’s charge-station planning algorithm, war broke out in Ukraine. Energy prices now strain many households to the breaking point. Gasoline has reached $6 a gallon (if not more) in some places in the United States. In Germany in mid-June, the driver of a modest VW Golf had to pay about €100 (more than $100) to fill the tank. In the U.K., utility bills shot up on average by more than 50 percent on the first of April.

The war upended energy policies across the European continent and around the world, focusing people’s attention on energy independence and security, and reinforcing policies already in motion, such as the creation of emission-free zones in city centers and the replacement of conventional cars with electric ones. How best to bring about the needed changes is often unclear, but modeling can help.

Nico Brinkel, who is working on his doctorate in Wilfried van Sark’s photovoltaics-integration lab at Utrecht University, focuses his models at the local level. In his calculations, he figures that, in and around Utrecht, low-voltage grid reinforcements cost about €17,000 per transformer and about €100,000 per kilometer of replacement cable. “If we are moving to a fully electrical system, if we’re adding a lot of wind energy, a lot of solar, a lot of heat pumps, a lot of electric vehicles…,” his voice trails off. “Our grid was not designed for this.”

But the electrical infrastructure will have to keep up. One of Brinkel’s studies suggests that if a good fraction of the EV chargers are bidirectional, such costs could be spread out in a more manageable way. “Ideally, I think it would be best if all of the new chargers were bidirectional,” he says. “The extra costs are not that high.”

Berg doesn’t need convincing. He has been thinking about what bidirectional charging offers the whole of the Netherlands. He figures that 1.5 million EVs with bidirectional capabilities—in a country of 8 million cars—would balance the national grid. “You could do anything with renewable energy then,” he says.

Seeing that his country is starting with just hundreds of cars capable of bidirectional charging, 1.5 million is a big number. But one day, the Dutch might actually get there.

This article appears in the August 2022 print issue as “A Road Test for Vehicle-to-Grid Tech.”

Keep Reading ↓Show less