Energy price calculation

The EMS never bases its decisions on the raw EPEX spot price directly. It first converts EPEX into the net injection price and the net consumption price using the contract parameters you configured. These net prices drive every price-based decision in the system, including curtailment and cost optimization.

The formulas

Both prices are expressed in €/MWh:

Injection price   = (B × EPEX) − injection cost − injection distribution cost
Consumption price = (A × EPEX) + consumption cost + consumption distribution cost

Where:

• A = consumption scaling factor

• B = injection scaling factor

• The costs are your fixed per-MWh contract components.

The injection price is what you actually earn (or pay) per MWh when you inject: it is the EPEX price minus the costs that come with injecting. Because those costs are subtracted, the injection price turns negative before EPEX itself does. The consumption price is what you actually pay per MWh imported: the EPEX price plus your consumption costs.

Contract parameters

You configure the following parameters for your project. They correspond one-to-one with the terms in the formulas above:

Parameter	Symbol	Effect
Consumption scaling factor	A	Multiplies EPEX in the consumption price
Consumption cost	—	Added to the consumption price
Consumption distribution cost	—	Added to the consumption price
Injection scaling factor	B	Multiplies EPEX in the injection price
Injection cost	—	Subtracted from the injection price
Injection distribution cost	—	Subtracted from the injection price

The break-even point

The injection and consumption costs are already included in the net prices — you do not set a separate threshold anywhere. The break-even EPEX price for injection is simply the sum of your injection costs:

Break-even EPEX = injection cost + injection distribution cost

Above that EPEX price the net injection price is positive (injecting pays); below it the net injection price is negative.

Worked example

With an injection scaling factor B = 1, injection cost €5/MWh and injection distribution cost €1/MWh:

Injection price = (1 × EPEX) − 5 − 1 = EPEX − 6

• The break-even EPEX price is 6 €/MWh (5 + 1). At exactly EPEX 6 the net injection price is 0.

• At an EPEX price of 4.01 €/MWh, the net injection price is 4.01 − 6 = −1.99 €/MWh. This is negative — injecting would cost you €1.99 per MWh.

• The injection price only becomes positive once EPEX rises above 6 €/MWh.

The −1.99 in this example is not a setting or a threshold — it is the net injection price at that moment's EPEX. The value that price-based decisions compare against is the injection price crossing zero, which for this contract corresponds exactly to EPEX crossing 6 €/MWh.

Where these prices are used

• Curtailment: PV production is limited when the net injection price is negative.

• Cost optimization: the battery is charged and discharged based on the net consumption and injection prices across the forecast.