So for me effectively a Safety range of 2kWh for unexpected Usage without having to resort to the grid.
This obviously also impacts peak shaving - especially in Austria starting with 2027 when grid cost are starting to be dependent on 15min peak over a month.
Sells battery (in green mode) for 15 minutes and then 15 minutes later buys energy from the grid (in the same amount) because the usage pattern today was slightly different.
Well, ok, there is ESS min SOC limit, which I vary to trick DESS to keep some “buffer” (from 00:00 to 12:00) - but that is a hopeful workarround (that no longer seems to get honored by DESS)
In addition to that there already seems to be some sort of DESS min SOC visible in mqtt, but this seems to change by some unknown means (controlled via DESS over internet scheduling by Victron DESS algorithms I assume)
So actually defining a DESS min SOC is not what we would want : maybe more of a “Target DESS min SOC” that is used for planning the schedule, but which does not charge from grid when it reaches its limit - only gets there when ESS min SOC is reached.
Instead it should probably modify its future planning (selling less and starting to prioritize charging from solar)
A workarround might be custom prices for grid export that would set export prices to negative in the morning, but then I guess scheduling would sell more (in the evening) before that artificial price drop…
I’d second the request — I’m running DESS in trade mode here in Finland on spot pricing and have seen exactly the same thing: the schedule empties the battery right before the expensive evening hours, and then a sudden load (in my case the heat pump kicking into a defrost cycle) forces grid import at the worst possible price.
My practical workaround so far: in winter I simply raise the ESS minimum SOC by about 5–10% on the cold weeks instead of trying to trick the schedule. It’s manual and not elegant, but it keeps the buffer I need. A dedicated DESS minimum SOC above the ESS one would definitely be a cleaner solution — hoping this lands with the peak shaving work you mentioned, mac.
Also recognize the Austria grid cost problem — we have a similar power-based fee element here, so keeping those spikes down matters twice.
My pricing in the UK works slightly different as I get blocks of cheap electricity for EV charging at fixed times but was still finding that DESS would over export and then due to increase load I would have to import at peak prices. As a solution I have implemented my own SOC limit for DESS in Node red which is a sliding value which reduces as I get nearer to my next cheap slot. If the SOC drops below this value then DESS is turned off. If DESS if off and the SOC is now once again above the limit then it turns back on. I have now managed to tune this ramp down of the limit do that I maximise the export credit but don’t ever need to import peak rate. I think this is the real power of the Victron DESS, you can customize it to you needs and it is flexible enough to cope with numerous different pricing structures.
