Electricity for a charging site is not billed the way home electricity is. A second component, based on peak power rather than total energy, often exceeds the energy cost itself.
Two meters of the same electricity
Commercial tariffs bill energy consumed and, separately, the highest short interval of power drawn during the billing period. That peak sets a charge applied across the whole month.
The logic is that the utility must size wires, transformers and generation to serve the maximum, whether or not that maximum lasts long.
A customer with steady consumption and a customer with brief enormous spikes may use similar energy while presenting very different costs to the network.
Fast charging is almost purely a spike
A high-power charging session pulls a large load for a short time. Several vehicles arriving together multiply that instantaneously.
The site may sit idle for hours afterward, but the month's peak has already been set. Idle time reduces energy sold without reducing the demand charge.
Low-utilization sites are therefore the most exposed. A single busy afternoon can define a cost the rest of the month has to cover.
Why session pricing looks strange as a result
Operators recover a cost driven by peaks through prices charged per unit of energy or per minute, which are only loosely related to what created the cost.
That mismatch produces pricing that varies by location and by time of day, and prices that stay high at quiet sites where drivers expect them to be low.
Idle fees and session fees are part of the same recovery. They push behavior toward shorter occupancy, which raises throughput against the same fixed costs.
Storage and managed power are the engineering answers
A battery installed at the site can supply part of the surge and recharge slowly, flattening what the utility meter sees.
Power sharing does the same in software, allocating a fixed site capacity across active stalls so the total never crosses a threshold.
Both reduce cost at the expense of peak speed. A driver experiencing slower charging while several stalls are busy is often seeing this mechanism working.
Tariff design is changing the picture
Several states have approved tariffs that reduce or phase in demand charges for charging sites, on the reasoning that early networks cannot reach the utilization the standard structure assumes.
Those arrangements are transitional and vary widely by utility, which is one reason charging economics differ so much across state lines.
As utilization rises, the peak is spread across more sessions and the charge stops dominating. The problem is a startup-phase problem that solves itself only with volume.