Intro
A CPO may want to apply more than one price model during the session. A concrete example is when the CPO has an electricity contracted tariff which consists of two price rates: a higher rate during peak time, and a lower rate during off-peak time. For example, the electricity costs for the CPO could look like:
- 0.53 €/kWh, for peak period, between 8:00 am and 10:00 pm
- 0.34 €/kWh, for off-peak period, between 10:00 pm and 8:00 am
Given this price scheme, the CPO has interest to reflect it towards the costs offered in its charger, and for that reason also wants the tariff for the charge session to be linked to those prices.
So far, our billing engine could only apply one price model for any given session. The default, without Time of Use (ToU) feature enabled, is that the billing engine will look at the price model that applies at the beginning of the session, and will compute costs accordingly (for the entire session’s duration).
Scope of use: This mechanism should only be used for internal sessions (internal CPO with internal eMSP) or towards Charge Assist ad-hoc payments. Using it with contactless payment terminals should be used with care, since it's likely not possible to provide the pricing towards end user with full transparency. To be clear, this means that ToU should not be used in roaming sessions. This is due to some uncertainty on how the behavior for these sessions should be (classical vs ToU, see scenarions 1 and 2 below) and the fact that roaming protocols are gray on this aspect
Time of Use Tariff feature: behavior and price computation
With the introduction of this new ToU feature, CPO customers can now apply multiple price models instead, and the cost calculation will consider all price models that may apply throughout the session.
Let’s consider the following tariff, which represents a potential CPO price model, according to the
pricing presented in the Intro section.
And consider a session than runs from 21:30 to 22:30, in a charger with the above tariff assigned to it.
Let us now look at the outcome of the session, for two configuration scenarios:
- Scenario 1: Setup GreenFlux supported until now – without ToU enabled
- Scenario 2: Setup with ToU feature enabled.
Scenario 1 – Without ToU:
Scenario 2 – Time of Use (ToU) feature enabled:
As follows, we summarize the main differences of the same session for the two scenarios above:
Scenario 1: No ToU | Scenario 2: Time of Use Enabled | |
Price visualization* | Price shown to the EV Driver is the one applicable at the moment of consultation | Price shown to the EV Driver will be the applicable price(s) in the upcoming 24 H |
Start and stop of session | Identical for both | Identical for both |
Price computation | Billing engine will pick the billing rule applicable at the start of the session and compute the costs. In the case exemplified above, the price 0.58€/kWh will be applied for the energy consumed in the whole session. | Billing engine will consider all applicable billing rules throughout the session, according to the time restrictions. In the case exemplified above, the price 0.58€/kWh will be applied for the energy consumed between 21:30 and 22:00, whereas for the energy consumed between 22:00 and 22:30, the price 0.41 €/kWh will be applied. |
kWh meter reading utilized | only start session meter value and end session meter value required | clock aligned meter values every 15 minutes required |
Charger special configurations required? | No | Yes, see next section |
* price as shown in an app enabled by Charge Assist API (e.g. Charge Assist app)
Technical details
Configuration steps - checklist
Hard requirements:
- The feature just works for chargers in GreenFlux backend
- The ToU feature works only with charging stations that send clock aligned meter values. Please note that not all charge stations support this functionality.
GreenFlux's responsibility:
Step 1: In order to be able to use this feature, EvPortal Super Admin (GFX staff only) needs to enable the illustrated flag at the CPO level (operators should liaise with your appointed CSM - Customer Success Manager). Only once this is enabled for a given CPO, the CPO operator is able to make the further required configurations to make the fully setup of a charge station.
Customer's responsibility:
Needs to be implemented in this order:
Step 2: The charger needs to be configured with specific configurations, please note though that these configuration keys may depend on the charger manufacturer. Hereunder the two configuration keys for a specific charge station.
The two configurations are as follows:
- The charger needs to send values every 900 seconds (do not configure a lower or higher value, it needs to be 900 seconds)
- The mandatory meter values (for time of use purpose) are thee following (please note that the exact nomenclature may depend on the charger manufacturer:
- Energy.Active.Import.Register,Current.Import (for single phase chargers)
- Energy.Active.Import.Register,Current.Import.L1,Current.Import.L2,Current.Import.L3 (for three-phase chargers)
For charge station manufacturer related information, check the manufacturer documentation/support.
Step 3: In order to finalize the the activation for a certain charger, the customer needs to activate the Time of Use flag on the charge station. To do that you can define it when creating a charge station and editing an existing charge station, in the following section:
Step 4: (optional, the time of use feature works fine, even without this step having taken place) In order to guarantee that the CDRs (obtained through platform API) contain charging periods for every 15 min period, then special configurations need to be defined for each platform API subscription. This needs to be requested through your CSM (Customer Success Manager). This configuration will have no impact in the information displayed in front-end, nor in .csv exported CDRs from EvPortal, only when retrieving CDR data through the API.
Happy Flow and Exceptions
When all the configuration settings (above) are in place, and the charge station sends clock aligned meter values, then GreenFlux will compute the costs accordingly.
What happens in extraordinary circumstances?
Situation 1: The charge station is unable to send the clock aligned meter readings:
In this situation, GreenFlux will flag the CDR as not valid and it will be listed in the CDR validation tool – check more about this: CDR Validation. CPO operator will then have two options:
- Option 1: Drop the CDR. This means that the session will be a loss for the CPO operator and the session would have been for free.
- Option 2: Accept the CDR, when this is performed, then GreenFlux will calculate the session costs according to the billing rule (pricing model) that is valid at the time when the session has started. Thus, only one price model will be applied throughout the session.
CPO operator should regularly (e.g. once per week) check the CDR validation tool to spot flagged CDR and take actions on them.
Situation 2: The charge station is offline throughout the entire session:
This is highly dependent on the charge station sending the information properly. When could receive all events in the correct chronological order, then we should be able to process and generate the CDR, provided the conditions in this article are met: CDR Validation (greenflux.com)
As a generic note, it is recommended that time of use feature is only enabled when connectivity between the charge stations and GreenFlux platform is quite stable. Since the Time of Use is substantially dependent on the reception of clock aligned meter values, connectivity issues may affect the order they are received in or not being received at all, which may potential lead to flagged CDRs.
CDR Cost Computation
For illustrating the calculation of CDR costs with DTB feature enabled, let’s consider the following tariff:
Now let’s consider a session in the following characteristics:
- Starts at: 11:00 H
- Ends at: 14:00 H
- Stopped consuming energy (entered in parking mode) at: 13:30 H.
- Charge station contains tariff Demo-ToU-Calculation, has ToU feature flag set to True and is communicating clock-aligned meter values
From above, we can extract that the car was a total of 30 minutes in parking mode.
The CDR will thus be composed by:
And the price computation will be as follows:
CDR special configurations
When detailed cost breakdown, including applicable tariff elements, are required in the CDR (see properties total_wholesale, total_retail and total_reimbursement in this page: CDR API (greenflux.com)), then a configuration item needs to be enabled in the platform API subscription. Only from the moment this configuration is enabled in the subscription, these properties will start being available to be retrieved (without retroactive effects). This configuration is requested through your CSM (Customer Success Manager).