Does DESS take into account the efficiency curve of charging/inverting?
Because almost always the system goes full power when the energy is the cheapest or expensieve even if the difference with neighboring prices are negligible.
In those situation it can even be better to spread and throttle charging/inverting over a wider period to accomplice a better efficiency with less energy waste and less wear and their on the multiplus(II) and batteries.
Hi @va13 and @grua thank you very much for the links!
I have a bit of reading and experimenting to do.
I’m using the trade-mode instead of green-mode to make use of high energy prices. Sometimes theres only one hour that the energy is very cheap or expensive and then the tradeoff with less energyefficency can be worth to use a higher limit.
Changing the charge-limit and SystemEfficency values looks like it can do the trick, thanks for pointing me to this info!
As far as I understood so far the efficiency is fixed to 90% per default. This is mentioned in the Node-Red Version: GitHub - victronenergy/dynamic-ess
I have a 48V System and my total efficiency is 80% (calculated from kWh counters in/out from VRM).
So I changed default efficiency to 80%. This can be done via dbus com.victronenergy.settings/Settings/DynamicEss/SystemEfficiency
I ssh’d into the Cerbo and changed it with dbus-spy (done in less than a minute).
DESS is now actually planning to charge cheaply tomorrow at an average price of 21 cent/kWh and will only draw from the battery at prices higher than 21 / 0.75 = 28 cent/kWh. At lower prices, it will draw from the grid:
Somehow that is not consistent. I had to increase the battery costs from 0 to 2 cents/kWh again for tomorrow. Otherwise the ratio (price when charging) / (price when discharging) < 75% would not have been maintained. It would then have been discharged at prices that were too low, so charging from the grid would not have been worthwhile.
