6.8. Load management

Load management systems offer a solution for charging infrastructure where a site has a limited electrical supply capacity. It can provide a means of avoiding capacity charges. It works by distributing the total power available across the chargepoints in use.

The image below explains the principles of load management, using three different charging scenarios.

There is a legal requirement for private chargepoints to be smart. This means chargepoints in residential developments and at workplaces lend themselves well to being load managed. The solution is particularly relevant to situations where cars are parked for longer periods as they have greater flexibility in their charging demand.

Load management systems will be less applicable to public infrastructure, where users expect a chargepoint to deliver its stated power rating. These users will generally be more time-limited, either by their own schedule or by parking restrictions, and will therefore likely only tolerate small reductions in the stated charger power.

In longer stay locations, this may be acceptable, an example being public or community car parks located close to residential areas that offer overnight AC charging. The Agile Streets trial referred to earlier in the guidance has been testament to this, as customers who are open to flexibility in their charging demand can reap environmental and cost benefits.

Another use case could be AC chargepoints at park and ride sites, as commuters often leave their car plugged in for the entire workday. The viability of this solution would depend on the parking rules in place at each site; specifically those rules regarding enforcement of overstays on fast chargepoints. It could however be technically feasible to introduce a solution where, across a portion of bookable chargepoints, drivers could input their desired charging quantity (kWh) and anticipated return time. The energy could then be distributed across the vehicles according to an optimised charging schedule.

Load management could also be used at public rapid and ultra-rapid DC chargers. Increasingly, chargepoint manufacturers are releasing units that offer load management capability. This allows greater asset efficiency as it can take advantage of two principal charging variables:

1. That some vehicles can DC charge at higher rates than others;
2. That the charging rate accepted by an electric vehicle battery automatically adjusts during different phases of the charge cycle (eg it reduces once the battery reaches 80-100% of charge).