Setting a quantity ef in storage units
Setting a quantity ef, the energy in a storage unit at the end of the time horizon. Its value will be the consequence of the last charging and discharging powers applied, the losses and the energy level at the last time step. This very energy level is not the final energy level because the last power values have not been applied.
Studying an energy system with a storage unit over a day, i.e. 24 time steps (hours). e!=e <=> ef!=e[time.I[:-1]] because the time steps go from 0 to 23.