Predicting the kW sweet spot in EV charge point variants

Despite their obvious similarity, not all electric vehicles can accept all charging paradigms. This inconsistency has led to variety in the charging infrastructure. For those companies supplying the industry, choosing the most appropriate equipment to manufacture and install can be a challenge.

The recent dramatic growth of electric vehicle (EV) sales is simultaneously encouraging and confusing. As markets emerge, they grow in several directions at once, so it’s hard to predict exactly how things will turn out. In the EV charger market, equipment manufacturers, installers and operators are running to keep up with unpredictable demand. Here’s how they’re approaching the challenge.

EV fundamentals

Electric vehicles fall into two broad categories: battery electric vehicles (BEVs) that rely entirely on batteries for motive power and hybrid electric vehicles, where the battery is complemented by a petrol or diesel engine. Hybrids are more common than BEVs, but that appears soon to change. According to ACEA, The European Automobile Manufacturers’ Association, BEV sales grew by 24.9% in the last quarter of 2021 vs. the same period in 2020. Comparable plug-in hybrid sales fell by 1.8%. It’s a similar picture in the U.S., where the Department of Energy reports that BEVs accounted for 73% of 608,000 plug-in electric vehicles sold in 2021. This sales figure is nearly double that of 2020.

The basics of charging electric vehicles

Public charge point installations are focused on meeting the needs of BEV drivers, even though plug-in hybrid EVs can use many of them too. Range anxiety is frequently cited as one of the most significant barriers to EV adoption. While that's undoubtedly true, many BEVs now boast a range of 300 miles or more, which is comparable with internal combustion engines. The challenge is to understand where and when EVs should be charged, and the best technologies to deploy for each situation.

As EV analyst and EVAdoption.com CEO Loren McDonald says, “Most cars are parked for 22 to 23 hours each day, so EV parking means EV charging.” That works well when you can get your car close enough to a domestic-level electricity supply at home or work, but there are many circumstances where that’s not possible. One example is in cases where only on-street parking is available.

In EV charging jargon, charging a car from an everyday grid socket is known as Mode 2 or Level 2. It will be limited to the rating of that socket, which in the U.S. is 120 volts at 15 or 20 amps — just 2.4 kW maximum. In the UK, sockets are commonly rated at 240 volts at 13 amps, a little over 3 kW.

Fully charging a Tesla Model 3 without a dedicated charger at home or work could take 24-36 hours, but you’ll rarely be charging from zero and overnight charging, say 12 hours, will often be enough to top up a battery. Mode 3 charging with a dedicated 7 kW charger and cable connects via a Type 1 or Type 2 connector, and the time to charge drops to 8 to 12 hours. In commercial installations, AC charging at up to 22 kW may be installed but such chargers are less common in domestic environments because a 3-phase AC supply is needed to deliver this power level and few homes have this.

While Type 1, 5-pin and Type 2, 7-pin connectors are both in widespread use today, most carmakers are moving toward the Type 2 format. Tesla, the leading EV maker with about 50% market share across Europe and North America, also uses the Type 2 connector for higher power, DC charging, known as Mode 4. Other vehicle manufacturers use CHAdeMO or Combo 2 connectors for DC charging.

Because of the higher power available, anything from 24kW to over 150kW, DC charging is preferred anywhere that faster charging is needed. Highway service stations, supermarkets and car parks at hospitality establishments such as restaurants are good examples. In these public charging environments, how do charge point operators and installers decide what to order from charge point manufacturers and what trends are now appearing?

It all starts with the driver

Driver behavior is the critical factor in understanding what charge points to deploy and where to locate them. That understanding doesn’t just start when the driver buys or leases the vehicle. With some of the data-sharing partnerships emerging along the EV supply chain, charge point installers are getting to know a lot about likely demand before vehicles even hit the road.

General Motors states: “To provide our customers more convenience when it comes to EV charging, GM is working with major EV charging providers including Blink® Charging, ChargePoint®, EV ConnectSM, EVgo, FLO®, GreenlotsTM and SemaConnectTM. Through MyChevrolet and other brand apps, customers will be able to easily see real-time information from approximately 80,000 places to charge throughout the U.S. and Canada, find charging stations along a route and initiate and pay for charging.” But of course, data is not flowing only to drivers, it’s coming back from them too.

McDonald cites a few factors that will determine what chargers are built and where they’re installed and operated. They include:

• - The number of deposits paid on electric vehicles, the vehicle types (and range) and the geographic location of upcoming EV drivers
• - Sales of EVs by type and locality
• - Patterns in car movements in various locations, usually extracted from mobile phone location data – mobile phone apps are integral to the EV driving experience
• - Availability of grid resources to power the chargers and whether these resources are from sustainable assets such as solar farms
• - The cost of electricity from the utility providers: “It may cost twice as much on one side of the highway as it does on the other.”

When these factors and others are considered, the volume of available data is vast. As a result, both installers and operators are now hiring data science teams and employing artificial intelligence (AI), primarily in the form of machine learning (ML), to identify trends and then build out EV charging infrastructure that will best meet the predicted demands of drivers. They hope to meet the demands of governments, too, as they strive to meet ever more stringent emission reduction targets.

Installation growth by type of charge point

Infineon’s whitepaper, “Realizing the future of fast EV charging through CoolSiC™-based topology design,” cites Yole Développement’s 2021 research report, “DC charging for EV: a decisive outlook for the power electronics industry,” to predict that high-end DC fast charging at 100 kW to 200 kW will see 30% compound annual growth rate during the next few years, the fastest in the sector, but even sub-50 kW charging posts will see double-digit growth.

Clearly, the convenience of at-home charging and the lower cost of low-power chargers will mean that the sub 50 kW segments will remain by far the largest by the number of units sold. However, high-power DC fast chargers are the only answer where charging needs to be done in little more time than it takes to fill up a diesel or gasoline car, so growth in demand for these is assured in public charging infrastructure. EVstatistics.com reported in May 2022 that 70% of Electrify America’s U.S. DC fast chargers are 150 kW, so that appears to be the sweet spot for public charging stations.

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