It’s no “bug”, more the absence of a desired feature: He likes to be able to use 20% as MinSoc-Setting, but avoid the system selling to grid bellow (for example) 40%, so there is “enough backup” for eventual consumption above the schedules estimate.
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Aww okii, I only enter how much KW of battery I want DESS to think it can use and not the total of all the batteries.
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that is smart.
Yet, it is a bit un-ideal as the battery-size is the underlaying value to calculate how much soc-change is required to achieve a discharge of “10 kWh”. So by “undersizing” the battery-configuration, the discharge-schedule and reality should be a bit off. (Planing for 10 kWh, but only discharging 8 kWh because SoC drops faster than expected for example)
True, but works well for me and have backup reserve, I also put discharge and charge limits to match the limits I have set in the cerbo and inverter, then DESS will map out its schedule to these specs. Everyone is different and it’s good fun to try every setting going to find your own.
I experience 2 issues causing unwanted grid usage:
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When there is more electricity usage during the night than forecasted, electricity in the morning is used from grid instead of battery because dess leaves no margin for extra usage.
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When the battery is charged fully during the day and dess is waiting for discharging period in the evening, grid instead of battery is used when solar doesn’t provide enough energy.
I would try dropping all the DESS settings by 1 or 2 kW to slow it down
Tried that already, dess will still discharge only for a longer period because it will recalculate schedule during discharge. It will still be on minimum soc in the morning.
Only lowering the soc with 10% with nodered around 2AM works around this problem.
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Manipulating DESS values seems like a patch, and not a very good one. DESS causes unwanted grid consumption so often that I find it strange it’s improvements were dropped.
Maybe it’s time for me to implement a min SOC manipulator like discussed above.
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Aww okii ace, least you have work around 
This is the scheduled graph. My scheduled graph is also looking good, no grid usage, but the actual graph at the end of the day is always different (which makes sense because it’s a forecast which will differ from the real usage and production during the day) and shows the 2 issues mentioned before pretty often.
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I would also appricate two soft limits:
- DESS min SOC - leave capacity to prevent grid consumption in the monring
- DESS max SOC - leave space in battery for more sun or less consumption
With 8ct/kWh or even 0ct/kWh selling price and around 36ct/kWh buying price, keeping (configurable) 10% room for uncertainty of prognosis whould be great.
In my case (PV: 8.5 kWp PV, battery: 56kWh, consumption: 12-30 kwh/day) I could avoid consuption at high prices completly.
Is there a feature request I could vote? I haven’t found one.
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