Worldwide revenue for electric vehicle charging services will rise from around USD 152 million today to 2.9 billion annually by 2023, predicts American market research firm Navigant Research. The number of charging stations should hit the 2.5 million mark by then – which appears at first glance to be good news for drivers and carmakers.

But much still remains to be done. Business models are underdeveloped according to analysts, particularly for commercial charging systems. Different variations being tried out include free charging, billing by time or by the kilowatt, and models based on advertising income. And more fundamentally, there are still not enough stations to begin with: According to Germany's National Electromobility Platform (NPE), for example, there are currently 4,800 publicly accessible charging locations in Germany and another 100 with rapid charging capability. Around 10,000 charging stations are available across Europe for environmentally friendly electric vehicles.

Policymakers, automobile manufacturers and public utilities are trying to change this. At the Washington Auto Show, VW and BMW announced their intention of investing millions in high-performance charging stations. Both manufacturers are cooperating with ChargePoint, which operates the largest network in North America with 20,000 stations. These "fast chargers" aim to become the industry standard.

In Germany as well, 7,000 rapid charging stations are meant to be installed in the next five years, which can fill up an eCar even from empty in just a few minutes. Another 28,000 regular chargers are also planned. Under the "SLAM" project (fast charger network for highways and cities), "power fuel stations" for electric cars should be installed at all German freeway rest stops by 2017.

Which standard is coming out on top?

To speed this expansion and provide legal certainty, the German government wants to set uniform standards for charging stations and connector systems in a "Charging Station Act." This would make the "Combined Charging System" (CCS) favored by German manufacturers mandatory for all new stations built by suppliers. This system supports both AC and DC charging. The legislations is causing chagrin for some manufacturers, as Japanese vehicles for example use a different type of connector. They would only be able to use the slower type-2 port for AC charging, which must be available as an option at all stations. No specific system is required by the carmakers themselves, and there is also no uniform approach to inductive (wireless) charging. However, according to the NPE every vehicle from a European manufacturer should support the Combined Charging System in the future.

Reception is more favorable for the requirement that all suppliers register with the German Federal Networks Agency, so that every available charging station can be indicated in apps and websites, although the move has been criticized as causing high administrative costs for non-commercial providers who might therefore choose to remove their stations.

"Charging stations need to become a node in the smart grid if we want to maintain grid stability as electromobility expands. This will only be possible with an intelligent charging infrastructure that can communicate with the power grid." (Enrico Nauck, Fraunhofer Institute for Embedded Systems and Communication Technologies ESK)

Interaction is the key

But all this can only be the start: for electromobility to gain ground, according to the Fraunhofer Institute for Embedded Systems and Communication Technology, there needs to be a unified network in which stations can be used regardless of vehicle make and location. This means that eCars, drivers, grid operators and billing services need to work together with a view to the long term.

Currently it is car owners who determine the charging time, length and required power, and thus also the electricity rate and cost. A grid-controlled charging system should therefore be developed as quickly as possible, where the total charge might be limited or the charging time shifted based on the status of the supply grid. This requires continuous data exchange between consumers in a given operating area and the grid operator. Synergies could also be achieved by connecting heat pumps or night storage heaters.

In a further phase, generation-controlled charging could be developed to accommodate fluctuations in renewable energy and decentralized sources. If the power flow deviates from forecasts, charging could be interrupted, or electricity could even flow back into the grid from the car battery.

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