All units concerning "electricity" are in kW or kWh
All units concerning money are in €
We follow the principle that: Power that "goes into" the local simulated energy system has positive values. Power that is "taken from" it has negative values. Examples:
The load profile usually contains negative values
The solar generation profile contains usually positive values.
When charging a storage, we use negative values as (from the perspective of the energy system) the power "goes out".
Power flowing from a GridBuilder (e.g. a "normal" grid connection point Grid) into the energy system is positive,
power flowing in the other direction is negative.