EV Capacity Planning & Load Management

Maximum Import Capacity (MIC) is the agreed maximum rate at which a site can draw power from the grid. Too low and the site pays excess capacity charges for every half-hour period above the limit, potentially making EV charging financially unviable. Too high and the site pays standing charges for unused capacity year after year. The MIC is also a key input to the DNO connection offer: a larger MIC requires more reinforcement, a bigger cable, and a higher connection charge. Getting the MIC right at the first application avoids both the cost of excess demand charges and the cost of renegotiating an over-sized connection. USP's right-sizing analysis determines the technically correct and economically optimal MIC for each project.

Dynamic load management (DLM) is the technology that allows a site to install significantly more charger capacity than the MIC would otherwise accommodate. By monitoring total site consumption in real time and automatically reducing EV charging rates when other loads are high, DLM prevents MIC breaches while maximising charger utilisation. For a public hub with a 40% diversity factor, DLM effectively multiplies the useful charging capacity for a given MIC by a factor of 2.5. For fleet depots with managed charging, the factor can be 2-3x. USP selects the appropriate DLM platform for each project, integrates it with the charger management system, and configures it for the specific load profile and MIC agreed with the DNO.

Half-hourly settled electricity tariffs mean that the price paid for each unit of electricity varies throughout the day, with significant price differentials between overnight off-peak periods and daytime peaks. For fleet depots where vehicles dwell overnight, shifting the majority of charging to off-peak hours can reduce energy costs by 30-50%. For public hubs where customers charge at variable times, the EMS can prioritise faster charging when prices are low and throttle when prices spike, reducing average energy cost without significantly degrading customer experience. USP advises on tariff selection and demand-shifting strategy as part of every capacity planning engagement.

USP applies a consistent six-step framework to every EV capacity planning project. Step one: calculate the theoretical unmanaged peak (charger count multiplied by rated power). Step two: apply DLM diversity to model the managed coincident peak (typically 40-70% of step one for public hubs, 30-50% for fleet). Step three: add base load from non-EV site operations. Step four: subtract BESS peak shaving contribution (typically 20-50% of the managed EV peak for a correctly sized system). Step five: project the demand trajectory over five years as the fleet or hub utilisation grows. Step six: compare the capital cost of a smaller MIC with ongoing BESS running costs against the capital cost of a larger MIC without BESS. The output is a recommended MIC and supporting justification for the DNO application.