For the past three days I noticed that my Victron DESS discharges the batteries to the grid early in the morning and late in the afternoon. The DESS is in ‘Green mode’ since I don’t want to trade electricity, I just want to optimally use my PV energy. Two examples of this strange behaviour are below. The first graph for both examples is created with Homewizard data collected from my smart meter, the second graph is from my Victron system.
Example 1 (Monday 2 March, 2 kWh in the morning and 4 kWh in the afternoon):
Example 2 (Wednesday 4 March, 3 kWh in the morning and 6 kWh in the afternoon):
I don’t know why this happens, all feedback and help is welcome.
I have four Pylontech US5000 modules, 19,2kWh in total.
Prices for today:
Prices for 2 March:
Prices for 4 March:
Not sure what you mean with DESS plan for tomorrow, but I think it’s this (5 March):
Not sure if I’m reading all the numbers correctly but it seems to me that these days you have way more PV than your consumption forecast. DESS will try to optimize costs by dumping the remaining energy to grid at the highest profit to make room for all the fresh PV in the forecast for the next day.
Imagine what would happen if it didn’t do that and saldering would end. It would mean you have full batteries in summer always. Consuming your own PV with very little consumption forecast and dumping other PV to grid even at negative prices. DESS, even in green mode, needs to make room to store forecasted PV.
Unless I’m completely misinterpreting your screenshots 
Good point, I think you’re right.
Last Friday five new PV panels (450 Wp) were installed on the roof of my house, that’s an increase of ~40% compared to what I already had. The new panels have direct DC feed-in to my batteries (MPPT), the existing panels have an AC inverter.
So apparently the DESS is not yet ‘used to’ my new PV panels, seems like a plausible explanation. I wonder what will happen in a couple of weeks.
