EV charging sites with more plugs get more use, Kempower finds

When it comes to public EV charging, more plugs may matter a whole lot more than bigger power numbers, according to new North American data from Kempower.

The Finnish EV charger maker analyzed public charging sites connected to its ChargEye cloud software and found that plug count had roughly three times the relationship with site utilization as total installed charging power.

Put simply, giving more EV drivers somewhere to plug in appears to be more useful than installing fewer chargers with a huge amount of power behind them.

Kempower found a correlation of 0.63 between plug count and site utilization, compared with just 0.228 between installed power and utilization. In its dataset, sites with eight plugs delivered more than twice as much energy as four-plug sites – 128,342 kWh versus 61,453 kWh.

That doesn’t mean charging speed isn’t important. It means installing a whole lot of power that sits unused won’t automatically attract more drivers or sell more electricity.

“Public charging is increasingly becoming an infrastructure utilization challenge, not simply a power deployment challenge,” said Jed Routh, vice president of markets and products for Kempower North America. “Our ChargEye data shows that giving more vehicles access to charging and dynamically distributing available power can help operators get more from their charging infrastructure.”

Why sharing power can work better

Kempower’s distributed charging setup connects multiple plugs to a centralized power unit. Its software then shifts the available power between vehicles in 25 kW increments, depending on what each EV can accept in real time.

For example, if one EV’s charging curve drops from 250 kW to 100 kW, the system can send that unused capacity to another vehicle instead of letting it sit idle. When enough capacity is available, a vehicle can receive up to 320 kW.

Kempower says the public charging sites in its dataset that used distributed charging averaged 83% higher utilization than sites with fixed-power dispensers. Its analysis suggests that around 100 kW of available power per plug is the sweet spot when all connectors are occupied.

For charging operators, that could mean adding more plugs without paying for enough grid capacity to deliver every connector’s maximum advertised speed at the same time. More drivers can plug in, and the system divvies up the available power based on what the vehicles actually need.

There’s an important caveat, though: Kempower’s white paper doesn’t disclose how many sites it studied, the observation period, how it calculated utilization, or whether it controlled for variables such as location, traffic, site age, pricing, and reliability. The results show a correlation – they don’t prove that adding plugs by itself makes a charging site busier.

Still, the findings make practical sense. A charging site doesn’t need enough power for every EV to pull its peak rate at once, because EVs don’t maintain that rate throughout an entire charging session. Spreading the available power across more plugs could allow operators to serve more drivers without building an oversized, more expensive grid connection.