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EV Charging Information

In systems where EV chargers are used, our EV charge room endpoint can be used to get the available charge room in the site. This charge room takes grid limits (contractual and physical) into consideration, as well as the available discharge power of the battery that is on site. This information is updated in the same cycle that the EMS is updated, usually every second.

What does EV charge room mean?​

The EV charge room indicates by how much the power limit of an EV charging station should be adjusted. It is a power delta. A positive number means that the power limit of a charger can be increased, while a negative value means that the limit should be lowered to aid the site to stay within the grid limits. The EV charge room is therefore NOT the power limit for the EV charger. As we do not know the active power output of the charger, we can only indicate the available room (or lack thereof) for the site to stay within the grid limits.

Please note that we apply a safety margin to the grid limits, to rapid adjustments of an EV charging station do not result in exceeding the grid limits. The default value configured by Ampowr is 10%.

Example calculations​

The following examples are and do not consider individual phases

// Example 1: Available charge room
Grid import limit: 100kW
Safety margin: 10%
Effective grid import limit: 90kW

ESS active power: 0kW
ESS available discharge power: 100kW

Grid active power: 60kW

// (Effective grid limit - Grid active power) + (ESS available discharge power - ESS active power)
// (90kW - 60kW) + (100kW - 0kW)
Total EV charge room: 130kW

-> This means that the EV charging limit can be increased by 130kW
// Example 2: Available charge room with no battery room
Grid import limit: 100kW
Safety margin: 10%
Effective grid import limit: 90kW

ESS active power: 100kW
ESS available discharge power: 100kW

Grid active power: 60kW

// (Effective grid limit - Grid active power) + (ESS available discharge power - ESS active power)
// (90kW - 60kW) + (100kW - 100kW)
Total EV charge room: 30kW

-> This means that the EV charging limit can be increased by 30kW
// Example 3: Site exceeding grid limits
Grid import limit: 100kW
Safety margin: 10%
Effective grid import limit: 90kW

ESS active power: 100kW
ESS available discharge power: 100kW

Grid active power: 110kW

// (Effective grid limit - Grid active power) + (ESS available discharge power - ESS active power)
// (90kW - 110kW) + (100kW - 100kW)
Total EV charge room: -20kW

-> This means that the EV charging limit should be decreased by 20kW

Response​

The response of this endpoint will contain both the total available current, but more importantly, the available current for every phase.

// GET /sites/:siteId/ev/charge-room
// Example response

{
  "requestId": "evf_1234567",
  "timestamp": 1719474475595,
  "total": 100,
  "per_phase": {
    "L1": 20,
    "L2": 40,
    "L3": 40
  },
  "unit": "A"
}