Hello everybody,
System efficiency has been discussed on this forum before Disappointed in export efficiency , Battery/System efficiency only 70%? and Multiplus-II 48/5000 efficiency curve - VictronEnergy . I decided to do a very crude efficiency analysis on a system working in ESS mode (0W grid setpoint).
For the DC power the DC shunt is used in the BMS and for the AC power the power reported by the MultiPlus is used. MQTT address: N/{installation_id}/vebus/{device_id}/Devices/{device_number}/Ac/Inverter/P. The system is one Multiplus in an isolated room (21 - 28 degrees Celsius) with a 48V 32kWh MG energy systems battery. A week of power data was analysed with the system in ESS mode. The data is put in 100 W bins, and the median is taken to compute the efficiency of the bin.
The bins are also coloured for the amount of data points in them. In ESS mode a relatively large amount of energy is inverted at AC power points where the MultiPlus is not at its peak efficiency. The battery efficiency during this week is calculated to be 96.6%, and the true system efficiency is 77.7%; this includes the battery efficiency.
Take all of this with a grain of salt. I did not calibrate any sensors and I have no clue how accurate each one is. The power data includes the BMS, the Cerbo and the continuous power draw of the Multiplus. I thought I’d share for the people who are interested.
