From the screenshots i presume you run DESS? Looks like DESS calculated it needed to use the grid to get to the desired SOC. Why that was the desired SOC? Depends on your prices and settings in DESS.
Yes - I have enabled DESS but as I am at this moment self efficient this should not happen - and the buy price was definitely not the cheapest (2-3am was slightly cheaper - not to mention around noon)
I already got an MQTT server in my setup (for other sensors) and adding an additional one is not supported - only possibility would be replicating from the Venus MQTT server…
Thanks - yes I have tried that and now I am using the ha plug-in victron_mqtt that I am now helping to improve to get all the DESS values into HomeAssistant! - and yes: also soon hopefully all the schedule values of DESS!
Unfortunately the behavior still persists on a general principle:
battery has sufficient SOc left (> 35%)
But DESS decides to use Grid over Battery
On the other hand: in the same hour it does deliver power to the grid from the battery
Net consequence is that I have to pay more than necessary - and battery costs are negligible (0.04Eu) compared to Grid cost (0.25Eu)
Blue (without text) is: self consume increased discharge!
My interpretation is that DESS has in its plan a (lower?) SOC target and when it reaches that because of some energy getting used, then it falls back to grid (to maintain Target SOC) even if there is no need…
Would you like to share your VRM DESS settings?
Which device provides the Cerbo the SOC?
What i find helpful sometimes is to also read Venus OS beta posts.
Sometimes there are insights to system behavior or other hints or tips.
It seems since the latest beta update two users stated that with DESS Trading the self consumption was managed better.
You are right the DC to DC converter is Not relevant in the night time.
DESS has trouble with peak usage as you have noticed when there are heavier loads switched on at different time intervals it cant know about up front.
Here the heat pump boiler every day runs on the same time. But if the airconditioners are running more than expected at night, DESS has some small grid usages, to keep up with the trading plan for that moment. It should be a bit more flexibel in these cases I think.
Sometimes when there is more capacity left in storage for the morning hours export, than there is no grid usage at night, at least I did not notice. But DESS is really good and the overall Victron experience with VRM is outstanding. So I don’t know if sometimes a 40cents is that big of an issue to make a fuss over it.
Just using it without DESS and do some node red and try your own systematic, you wil notice how hard it is the more you try to dive into the matter. I tried and it cost a lot of time, I gave up because DESS is doing a great job, at least for my system it is.
Just curious about your DESS Settings?
perhaps you can also take a peek at the SOC data graph under advanced in VRM?
Often the SOC from the BMS is not that accurate, having percentage jumps. But I don’t know about the Pytess BMS.
I use a Victron Shunt for my system and also noticed these grid usages sometimes though very small, it does not irritate me with trading.
The Victron Shunt is very precise managing 90kWh (next month 150kWh) storage. I use 3 multiplus 8000 and at the beginning playing with DESS was not that satisfying at all. It irritated me also that it had used grid at night and every 60cents. Playing with the price settings and observe can give some insights too.
I use the latest Venus OS beta and at the moment I am very happy with DESS trading. With the VRM database issues last week it missed some peak price for selling but it is what it is. An outage can occur also on the internet Connection and so on.
@Ersus : what I find unexplainable is that at night DESS is running without any SOC target (=0)
but when something unexpected is kicking in for a short period (hot water boiler running 10min) of time then it changes its idea and starts to increase the Target SOC all of a sudden!
06:11:39 Battery draining drops to close to 0 Grid consumption drops to 400W (a ramp down)
from then on battery is sligthly charging and GRID consumption at arround 400W
06:15:03 DESS changes to:
reactive strategy: Schedule minimum discharge
Target SOC: 66%
SOC: 68%
Battery consumption increases
Grid consumption 0W
I understand that the DESS is complex.
But this scenario is simple enough and in the end this switch of reactive state and increase in Target SOC needs to get investigated - something is going wrong there!
For what it is worth - why would it decide to increase Target SOC? Maybe Solar Power was just starting to kick in a little - but definitely not at above 200W…
and if you look instead at yesterday evening (earlier post):
There the Target SOC was 0 and all of a sudden changes to a high value close to existing SOC.
And then again it drops to Target SOC of 0.
Something is not right there and victron should have an explanation why this is happening.
unfortunately there are no logs (taht I know of) that one could look at locally to find some motivation why DESS would be deciding on such a plan change.
maybe logging those would at least give an indication why…
You see that the DESS SOC Schedule is zero when ‘Self consume’ is Prioritized. Perhaps this is wanted so the system wont interact with the ‘Self consume’?
From your screenshots, I can see, that the gx went into Idle_maintain_target_soc during pro grid. This happens, when your system reaches the calculated target soc too early. (That can have many reasons)
However, the cut there is “too hard”, so in the current betas, this has been fixed. If this situation appears, the reactive strategy would be “Selfconsume_accept_bellow_tsoc” and just continue to drive loads rather than idling - accepting that soc goes bellow target soc and let the scheduler make the best out of it
So, you can either try the beta, or wait for the next official release.