Dynamic electricity tariff for e-cars: A test on public charging infrastructure

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Anyone who doesn't have a parking space with a wallbox is excluded from some advantages of an electric car – especially from cheap electricity prices: On average, at home per kilowatt-hour according to BDEW 39.6 cents are due. This price includes a monthly basic fee. New customers sometimes pay significantly less, so a price comparison via the usual portals can be very worthwhile.

An electric car runs cheapest with energy from a depreciated photovoltaic system. But even without solar power, there are reduced grid fees. In addition, since January 1st, suppliers must offer a dynamic electricity tariff, which can be particularly cheap at certain times. In a pilot project at enercity in Hanover, this idea is being transferred to public charging infrastructure: at eleven central locations in the Lower Saxony state capital, charging stations with hourly changing tariffs are in operation under the keyword FlexLaden. Good reason for heise Autos to try it out in practice. Does it work?

Potentially higher revenue

What enercity is doing here combines several approaches that can make public charging more attractive in the future. These charging stations work with direct current and offer 150 kW of power. While such fast charging stations cost more to invest in because they have to be connected to the medium-voltage grid, they are more economical from the operators' perspective because more kilowatt-hours can be sold per unit of time. This pays off with sufficient utilization. Furthermore, public space is used better: if the German vehicle fleet is predominantly converted to electric cars in the long term, charging spaces must be cleared quickly for others. DC columns are the logical answer.

The electricity at these charging stations can be activated without a contract or registration. In the industry, this is called ad hoc charging. An additional special feature of the enercity pilot project is the partner ev pay: The company, specializing in software, handles billing in compliance with calibration law. Among other things, ev pay can integrate dynamic tariffs. From the perspective of electric car drivers, paying with a smartphone or credit card is particularly low-threshold. For this purpose, ev pay also provides the terminal.

Grid-friendly charging

Dynamic electricity tariffs are, of course, not an end in themselves. Rather, they follow the principle of grid-friendly charging. The production of electricity from renewable energies is in the previous year to date according to Fraunhofer ISE at 62.5 percent – and it fluctuates. At the same time, demand is volatile. With the steering effect of a dynamic electricity tariff, electric car drivers are encouraged to charge at a sensible time. Demand is attracted by supply. This potentially creates a win-win situation.

So, off to Hanover. An Xpeng G6 is available as a test vehicle, which can charge at up to 451 kW. How much do the Alpitronic charging stations, designed for 150 kW, actually deliver? First, they have to be found. Due to data protection regulations, enercity provides the street of the location, but not the house number. The charging station in Ritterstraße was still clearly visible – and it was free.

Activation at the payment terminal

Of course, customers with a charging card or a charging app can also activate the electricity at this DC charging station. The highlight remains ad hoc payment with a credit card. A clearly visible graphic makes it clear that the credit card must be held to the payment terminal. At this point, however, misunderstandings can arise: on the control panel, the function must first be activated by pressing and confirming, and the desired of two charging points on the station must be selected.

Subsequently, the credit card is checked for coverage with an imaginary advance payment of 80  Euros. This can also be confusing if you are not used to it. Only the electricity that has actually flowed is billed. This then flows quite "quickly". The charge level of the Xpeng G6 upon arrival at the enercity charging station was 78  percent. The power immediately increased to 149 kW. This documents, on the one hand, the immense fast-charging capability of the Xpeng and, on the other hand, that the Alpitronic station releases full power if no vehicle is at the second charging point – and that was the case.

Competition for major operators

Ad hoc charging without registration, it is obvious, has a very large potential, especially at the charging parks of discounters and DIY stores. For these operators, it is not important to force users into a contract with a monthly basic fee. With the payment terminal, billing is low-threshold and simple. In this context, the current situation in the public charging market must be described again: The National Charging Infrastructure Control Center states that more than 95  percent of electric cars are charged via contract if it happens at a public charging station. Ad hoc payment has so far played only a minor role.

The reason is offers like the L tariff from market leader EnBW: at the locations of this operator, and mind you only there, the kilowatt-hour costs 39  cents if a monthly basic fee of 11.99  Euros is paid. With other operators, the rate can rise to up to 89  cents. Contract users will therefore use the EnBW charging stations if possible and thus utilize them better.

The market is starting to work

The result is an oligopoly. Few participants determine market events. Supermarkets and DIY stores, for whom ad hoc charging is particularly attractive, are creating serious competition. With software solutions like those from ev pay, it is possible to integrate charging processes into the existing checkout system without any problems. This allows low prices to be achieved.

Enercity is still a bit away from the particularly low electricity prices like those at Aldi (29 to 47  cents) or EnBW: enercity announces the hourly tariffs for the following day around 1 PM and at the same time guarantees a maximum limit of 67  cents per kilowatt-hour. In the heise Autos experiment, it was 59  cents. Less than 50  cents are rarely seen.

Perhaps dumping prices are not the point in this first step either. Rather, enercity and ev pay are demonstrating the practical feasibility of a principle – and it works. My, perhaps too bold, prediction: If there is DC electricity for 29  cents per kilowatt-hour at two in the morning, people will get up. This is the new interpretation of searching for the gas station with the lowest fuel price.

(mho)