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Peak billing
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The peak billing model is intended for systems using power control. The model is based on the irradiation measured at the PV system site at the time of curtailment. The formula is based on the “Spitzabrechnungsverfahren” from the German Federal Network Agency (Bundesnetzagentur) but can be applied to any location, provided the system fulfills the prerequisites. VCOM searches the last 3 months of data for a valid reference period.
Prerequisites
Irradiation data: the system must have an irradiance sensor
Grid operator's relative active power setpoint value
The derated power must be lower than the expected power
The measured power must be lower than the expected power
Example
In the chart, you can see that the grid operator curtailed the system at 4:30 PM. The yield losses are then calculated on the basis of a ticket.
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Chart: curtailment example
Ticket with yield loss calculation: peak billing
Formula
Peak billing formula
Variable | Explanation |
|---|---|
WA,i | Curtailed energy during the 15-minute interval i in kWh |
Gi | Average irradiance during the 15-minute interval i during the curtailment in kW/m² |
PVZist | Average actual feed-in during the comparison period in kW |
GVZ | Average irradiance during the comparison period in kW/m² |
Plim,i | Setpoint value in kW |
Info
The comparison period is the last calendar day on which there was no curtailment measure. Only the quarter-hour periods in which the average output is at least 10% of the system's nominal output are considered.