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spacecow avatar image
spacecow asked

How to disable charing from the grid and allowing AC coupled PV charge battery

Hello,

I recently got my system ( 3P MultiPlus-II 48/5000/70-48, 3x Voltsmile V10, SmartSolar MPPT VE.Can 250/70 rev2 & SmartSolar Charger MPPT 150/35, 2x Deye SUN-M80G3-EU-Q0, 1x Deye SUN-M80G3-EU) installed. Due to the bad weather I ran into a problem, when the battery reaches minimum SoC it gets charged from the grid. When it changes to chraging, the SoC instantly jumps by ~5% and 10 seconds later the battery is in discharge again with another jump of -5% SoC. Then this repeats around 20 seconds to 1 minute, depending on the load.


How can I generally disable charging from the grid.

I found the solution with setting in DVCC "limit charge current" to 0A and 'feed in excess DC PV power' to keep charging from MPPTs with no limit. With this the battery is marked with ESS #6 an should not be loaded from the Multiplus.

But I think with this charging from the AC coupled inverters (all at AC OUT) wont work as the Multiplus will never charge the battery due to the limit. Unfortunatly due to the weather I was not able to verify this.

Is ther a way to only disable charging from the AC-In but allow charging If I have excess power from the AC coupled PV inverters.

I tried looking for this but only found the DVCC solution.


battery chargingESSDVCC
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matt1309 avatar image matt1309 commented ·
Does the same solution you've applied for DC not work for AC? ie enabling AC coupled pv - feed in excess. Not work?
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spacecow avatar image spacecow matt1309 commented ·

Even disabling charging via DVCC "limit charge current" to 0A does not work as you could seeESS #6 "User configured a charge limit of zero" (its in german) is visible but still the battery is charged from the grid.1712611169478.png

Is there any idea how to solve this.

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3 Answers
shockbroker avatar image
shockbroker answered ·

This is a confusing question. At minimum SOC you´d actually want to charge with AC before you hit 0% or not? Isn't the real problem the 5% jumps in SOC at start/end of charging? Why do you mention these when you want to disable charging completely? And, is the reason that you just don't disconnect the grid that you intending to feed back?

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spacecow avatar image spacecow commented ·
I don't want to charge from the grid at all, and I don't want to disconnect from the grid as I sometimes have insuficient power from my pv or excess power to feed back.
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duivert avatar image
duivert answered ·

hi whats your grid set point?

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spacecow avatar image spacecow commented ·
My grid setpoint is 0W
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Alexandra avatar image
Alexandra answered ·

Simplest way is to disconnect from Grid. Not a great solution in low lights. Unfortunately AC PV uses the same mechanism as grid charging. So it is either that or disable the internal charger and relay on DC mppt to get the battery full.

The only other way is to make sure peak shaving is off at min SOC.

As a guess there is a power assist happening which draws the battery down, then a top up to maintain a level.

And to add to that you might find it is the battery sending the charge signal and the then system overriding it, hence the up/down hysteresis. So maybe a slightly higher min SOC will help as well.

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spacecow avatar image spacecow commented ·
Disconnecting from the grid is not an option, currently I need more power than I get from the PV. Charging from the AC coupled PV could be distinguished if there is exceed AC power so the powermeter measures a negativ power this amount can be utilised for charging, at least I would expect this behaviour.


I have peak shaving completly off.

I increased the min SoC from 10% to 25% with the same effect.

The jump by 5-10% of SoC between loading and unloading might lead to this repeating behaviour, but without loading there should be no effect from this.

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