Excess electricity is surplus electrical energy that must be dumped (or curtailed) because it cannot be used to serve a load or charge batteries. Excess electricity occurs when surplus power is produced (either by a renewable source or by the generator when its minimum output exceeds the load) and the batteries are unable to absorb it all.
Note: It is possible to have a capacity shortage on one bus and excess electricity on the other in the same time step if there is an undersized converter or a converter without the "Parallel with AC generator?" option selected.
