Add battery inverter efficiency to the equation

[jakenl]

When energy is returned to the battery or used from the battery, there are conversion losses.

Panasonic claims a 'Maximum inverter conversion efficiency' of 90%
Tesla mentions an 'AC-efficiency' of 93% (with the remark: 'AC to battery to AC')

To me unclear whether both mean that 1kWh into the battery means 0,9 or 0,93kWh from the battery, or that the efficiency losses go both ways: 1kWh into the battery stores 0,9kWh and using it from the battery returns only 0,81kWh

The easiest solution is adding 2 parameters to the script: efficiency to and from the battery. The script will be distributed with this parameter on 100 (100%), so it doesn't effect the existing way of using/logging.