I really would like to have a feature in ESS allowing to schedule discharge. Maybe to deny discharge for certain hours whichever way it suits better. I
I am using schduled charging partly for this purpose but it isn´t the same. It works fine for charging dring cheap night time slots.
There are hours slot where I do not want to consume my battery energy as price is so cheap. This way my battery also lasts longer time covering high price slots.
Setting discharge limit is too difficult by reducing/increasing power steo by step. It could be more like turn on/off, this is what I do in Node red now. I couldn´t find a way to do nice timer control but I am sure there is way to do it.
Control via ESS menu in VRM would be much better way to handle it.
Zusammenfassung
I think DESS is exactly doing that out of the box.
When consumption from Grid is cheaper, it won’t discharge your battery.
I don’t know the exact formula victron is using on that, but from a logical point of view, i would assume it’s
- costs/kwh (storage)
- plus price you get for feedin 1 kWh. ^1
- plus some inefficiency surcharge, probably 30% (actually based on a variable system efficency, according to the docs)
So, in my case, DESS would avoid the battery discharge if Grid Price falls bellow (3+8)*1,3=14.3 cent - which is almost never happening during times where a discharge is usually required here.
Make sure you setup your battery costs properly, then DESS will do the right thing, even if it might not 100% match your expectation.
^1 This is nowhere mentioned in the docs, but I would assume that victron is not considering the physical costs as real costs/kWh - the energy itself has to come from somewhere, so there are opportunity costs due to NOT selling that energy but charging the battery.
You should be able to verify this: Say, this night you will have Grid costs of 20 cent - set the price per kWh in DESS to 21 cent, and see if it properly avoids to discharge the battery during that time.
(Need to do this early, to give the schedule time to recalculate)
I’ve just updated my Battery Costs to “30 cents/kWh” - and will check what is happening now.
First test (Grid-Price is currently 22 cents) do not show any attempts to offload consumption to grid instead of battery. Will leave that sitting for a while, may take time to take effect.