Minimum SOC Using DESS

Q&A and troubleshooting DESS
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Am I correct in thinking that there’s only a single Minimum SOC setting when using DESS? This is the value in Settings > System Setup > ESS > Minimum SOC?

If this is the case, what I don’t understand is why there isn’t a separate minimum SOC setting for the DESS system? No one wants DESS to drain the battery anywhere near the minimum SOC value because the battery will idle at that point and the system will start using grid power. DESS should have a configurable “buffer” above the battery’s minimum SOC.

This may be something that the algorithm learns over time but in my opinion, you should be able to set this manually.

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Yes there is only one setting. A second setting has been requested multiple times, don’t know if it’s on the roadmap.

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Ok, thanks. I didn’t think I was going mad :slight_smile:

Seems like a very obvious omission to me. This morning DESS quite happily ran my battery all the way down to the minimum SOC and I spent a couple of hours running off grid power before the solar kicked in. A few hours earlier it had a two hour off-peak window it could have used to charge the battery but decided not to for some reason. It was probably a bit cloudier than expected this morning so maybe the solar forecast was a bit optimistic.

Either way, DESS shouldn’t run the battery down so low. It should by default have more of a buffer at the lower end of the SOC range. If your battery’s minimum SOC is 20%, DESS should target maybe 30 - 40% minimum. Obviously this varies wildly with different systems and use-cases so it should be a configurable parameter.

Hopefully they will implement this feature soon!

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Was here for something else, but hey this post was on top.

Also found it a problem, So just made a nodered flow for it. My minimal battery SoC unless grid fails is depended on the amount of daylight hours.

Currently in a Summer, Autumn/Spring/Winter setting. (25%/35%/50%) and possible 10% lower if gid power price excluding tax go’s below 0

Was my first time nodered, still tweaking.

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I fully agree to this.

There seems to be already a margin of error in the current DESS calculation behavior, since in the plan it goes to minimum 21%, meaning 1% above the min SOC of 20%. But 1% of the battery is, for most systems, not a lot. I other words, you installed a batterysystem to become more independent on the electricity grid during peak times, but in the end, during that peak period you still need to be carefull not to turn only this extra 70 watt lightbulb.

Ideally you want it to be a user setting, but setting it already 5-10% higher would already be a big step (i.e. calculate DESS with minimum expected value to be 25-30%). Especially now that in the Netherlands we are starting the wintertime where 1% safetybuffer in the DESS calculation is really nothing.

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