I have tried to switch from Trade mode (without any Battery limitations) to Green mode ( still without explicit Battery limitations like: “disable discharging battery to grid”) this morning (10:16 as per event log) and later tonight (6-8h later) DESS was still draining the battery to grid even though the definition of green mode says that it will not do so.
Quote: “energy in battery is reserved for consumption”
Only when I change battery limits to: “yes, disable discharging battery to grid” did it change its planning… (I did check this a few days ago already with the same observation)
So is this as expected that there is no difference between Green and Trade mode any more with regards to battery to grid?
But one note: when I changed (at 10:16) to Green mode the scheduling did change: it started to fill up the battery first and feed to grid only after filling the battery to 100% - before the change in trade mode it was solar to Battery (Visible also in the second graph/screenshot)
Running on v3.80 (and formerly on 3.80 Beta as well).
I have a system exhibiting the same behaviour about 20 hours after switching from trade to green. in practice system behaviour has not changed, it discharges the battery to min. soc to make room for (probably wrongly) predicted solar, resulting in needing to buy expensive grid power later on.
I have tried some things (other firmware, resetting forecast, changing dess settings, …), the only option i have left is completely disabling and resetting the system deleting the vrm instance and start anew. Not looking forward to that.
Can someone from victron clarify if the description is wrong or the system is malfunctioning?
The only thing you can do is set a battery restriction - see screenshot above.
Then green mode behaves as green mode is described.
As far as I can tell the difference is essentially if battery is charged from solar first in the morning and only then exported to the grid (green mode) only when DESS deems it beneficial from an income/cost perspective (Trade mode) - so it schedules charging later, which may be too late if solar predictions are wrong and/or energy usage during the night is slightly off…
The description of Greenmode needs a tiny clarification there.
Green Mode indeed is able to sell battery 2 grid with no restriction applied.
That is for so called “Green-Electricity-Storage” where you plan to feedin solar at a later time.
It does only sell what it expects to be unneded for self-consumption.
And that is what is meant with "“Only sell surplus after consumption and battery charging”. Energy in the battery NOT scheduled for consumption is considered surplus that can be sold back to grid.
This could be made a bit clearer.
If you don’t want this, or your contract does not allow this, that’s what the permanent battery2grid restriction is for.
Well clarification on the descriptions should be the first step, because to me as of now it implies “Restrict Battery to grid” is enbled when using this mode.
But in the grander scheme of things the issue really is the way that DESS is scheduling and what are the effects when something unexpected is happening on the consume, production side or grid side.
There should always exist a buffer of energy in the battery in case something happens before resorting to importing from grid - there seems to exist a bit, but it is unable to handle peaks of changed usage (weekends washing machines started earlier, making breakfast earlier/later than “normal”, more such events together,…).
Indeed, looking at DESS behaviour the ONLY difference is that green mode does not charge the battery from grid with intent to sell. ALL other behaviour is the same right?
There is one other deviation that I am able to observe (or had observed previously - things might have changed since):
in the morning green mode charges battery first and then exports to grid
Trade mode exports to grid first (when prices are more beneficial for selling) and then when prices are lower or negative it charges the battery (and under wrong conditions/weather predictions it will not be able to charge the battery to survive the night, as it starts too late)
(That’s what I have observed with dynamic Pricing when export to grid…)
This is why I started this thread as during autumn/winter I changed back to green mode to first fill up the battery if ever possible…
Not what im seeing, in green mode it exports everything up to the min soc (so both PV generation and battery power get exported) when power is expensive and solar power is expected later, just like in trade mode.
I am just talking about morning - at least when I made that observations.
And at that time (winter, early spring?) I believe it did not sell battery to the grid either (so the implicit limitation of Battery to grid) was in place.
That may have changed since.
Not knowing if it is a KI/trained model used for DESS it would at least explain the new behavior that when seasons change the “recent” behavior is much more important than something learned last Autumn or spring…
Selling to grid in summer in green mode is no (real) issue (I was running trade mode anyways), but now with sun risings later every day this “selling too much” and then not having enough a bit later as local consumption shifts becomes an issue.
And here KI training definitely would favor recent data and hence be more susceptible to take wrong decisions… The problem might not show up so badly in a month or so - in some ways it is similar to the question “what shall I wear this morning?” You also go wrong more often in Autumn than you do in summer or Winter…
One thing is that strangely when DESS min SOC is reached then the DESS min SOC is increased from 25% to 30%.
Here is where this alternative min SOC limit would help:
Assuming DESS min SOC is always > ESS min SOC (say +5% - ideally configurable)
Then reaching that limit would trigger a separate state - DESS low SOC (not ESS low SOC) and still would let it slide until it reaches Real ESS min SOC.
And then it would start charging from grid - that would have given me a buffer (because of the 5% difference) of 1Kwh before charging the battery from grid.
As a not so nice side effect we also have the fact that the consumption from grid peaks at 6.5kw - and this would negatively impact Grid costs for the wholemonth (such rules starting in January in Austria)
Not what im seeing, in DESS green mode with no battery to grid allowed it still exports to grid before charging the battery. See for example the plan tomorrow, battery SOC down to 10% (min. SOC).
For me green and trade mode behave exactly the same except maybe not charging from grid with the intent to sell (not applicable, see electricity prices).
This happens due to the ESS Mode “Optimized WITH Battery Life”. I would recommend to switch to Optimized without Battery Life and eventually use the dess scheduled balancing instead, if your system requires occassional help to reach 100%. (Mostly happens during Winter)
That 5% minsoc change by ESS is mostly a undesired hickup for dess enabled systems.
Then that was improved as well. Didn’t use bat2grid restrictions since a long time now.
If there is plenty of sun, Green mode behaves almost exactly as Trade mode. Based on solar prediction, it sees that 100% SoC will be reached while there is still more sun in the evening, so it finds the best time to sell excess to the grid, and in your case, the best price was in the morning.
The biggest difference between these two modes is when there is not enough sun to charge to 100% or if the sell price is lower than battery costs. Trade mode will calculate maximum profit and might sell everything to the grid without charging the batteries if there is no price increase later. Green mode will not sell anything if it cannot charge the batteries to 100%.
Today I had to switch to Green mode since my sell price was at 0 or below 0 the whole day. Trade mode decided to curtail solar production and not charge the batteries, as it calculated that charging costs money (half of the entered battery cost per kWh), and it is cheaper not to charge. I wish Trade mode had an option to not waste the solar and ignore the battery cost when it is not possible to sell to the grid yet the batteries are not full.
