question

solarlion avatar image
solarlion asked

ESS – Always go On and Off instead supplying less power?

We have 3 Phase Multiplus II 5000 with 8 Pylontech US3000C and CerboGX in ESS Configuration. 16KWp Solar array DC coupled with two MPPTs.
Starting autumn our solar yield is way less as in summer.
So following starts to happen when the house constantly uses 1000W+ but Solar only Supply 200W.


- Battery fall to minSOC and Inverts stop to supply Energy (currently 40%)
- House run of the Grid and solar is loading the battery to minSOC + 3% (43%)
- ESS Start again, drain the battery very quick back to minSOC
- … repeat

So during the day, we have 10 to 15 times the cycle “Load to 3% - drain very quick back to minSOC”. This can’t be good for the battery.

Any setting I can make, so that the System just send the solar 200W to the house without this “Load / Drain” cycling?

Multiplus-IIESS
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1 Answer
nickdb avatar image
nickdb answered ·

That's kind of how it works. It sounds like you don't have batterylife enabled, I would suggest you use the optimised with batterylife mode to keep the battery in the right zone.

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solarlion avatar image solarlion commented ·

Currently battery live is disabled, and I set ist manually. I dont like the algorithm, when it starts to load in the night and not using the solar coming 1 hour later... So I set it during autumn to 40% minSOC and in Winter to 60%minSoC without thie algorithm. Out of my research there cant be any damage to the battery when minimum is 60% charge for a few weeks. Thats also how the batterys are stored during transport ore in warehouses.

Do you think there is a problem with battery live when 60% minSOC in winter?

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nickdb avatar image nickdb ♦♦ solarlion commented ·
Pylon (and other manufacturers) want their packs regularly fully cycled. Leaving the battery at that level for weeks will encourage SOC drift, because the BMS can't sync, and cell imbalances.

It is pointless setting a minimum SOC so low if you can't get it to fully charge at least every few days.

Batterylife works fine for what it was designed for.

When there is such a difference between power required and power generated it won't work properly until that balance changes.

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solarlion avatar image solarlion nickdb ♦♦ commented ·
With the values I mentioned, battery get to 100% charge at lest 2-3 times a Week. Only on a few days with extreme Rain or snow not.
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nickdb avatar image nickdb ♦♦ solarlion commented ·
That's fine then.
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