question

malcolmurwin avatar image
malcolmurwin asked

Ess drains batteries into grid

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Has anyone seen this before where ESS drains the batteries into the grid?

ESS
4 comments
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

We need more information about your system and maybe some screenshots of your settings (Venus and VE.config).

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netrange avatar image netrange commented ·
  • ... Deleted by User ...
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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ netrange commented ·

Hi @Netrange

Please don't draw conclusions too fast from a single topic, I think that was related to something else.

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ganderpe avatar image ganderpe Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Helo Daniël Boekel,

does Victron have an Idea why this could happen?
Or is it even a Feature?
I believe it's an ESS Problem under certain conditions.

The BMS from the BYD Lithium Battery was functioning correctly.

I would appreciate it to have an Statement of the Professionals....

Thanks in Advance


Peter


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10 Answers
Rob Fijn avatar image
Rob Fijn answered ·

Dear All, interesting. Yes this happens in my system too.. Not every day.. sometimes.. This can not be seen on the VRM, as this happens only for a few seconds. Have seen this happening only when the battery still need to be charged.

The system I have is small: Multi 12/800/35 MPPT100/50 2xPV 280Wp and a 60Ah Lithium LifePO4(Smart Victron). ESS = Optimized(with BatteryLife) Minimum SOC 65% GridSet point 50Watt

Regards, Rob

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malcolmurwin avatar image
malcolmurwin answered ·

Hi,


system is 2 x multi 48/5000/70 in parallel, 800Ahr VRLA, 2 x SMA solar inverters, color controller firmware 2.66.
ESS Optimised(with BatteryLife), Minimum SOC=80%.

System has been running for around 5 years fine and this problem started about 8 months ago. To solve it I move ESS to “Keep Batteries Charged” but then I cannot take advantage of the batteries unless grid fails.

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Warwick Bruce Chapman avatar image
Warwick Bruce Chapman answered ·

Your ESS Minimum SoC is set to 80%.

If you want to be able to use the top 20% of the batteries to support non-essential loads (upstream of the inverter), but not feed into the grid, then add an energy meter eg. ET112 or ET340.

If the inverter loads are all you want batteries to support with ESS, then just disable DC-coupled Feed-in in the ESS menu.

(Previous version of this answer included the following incorrect statement:

If you have DC-coupled feed-in enabled, ESS will discharge your batteries into the grid until 80%.)

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malcolmurwin avatar image
malcolmurwin answered ·

Problem is not PV related as the discharge happens day and night. It discharges to SOC then recharges to 3% above SOC then cycles this continuously

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Warwick Bruce Chapman avatar image Warwick Bruce Chapman commented ·

Please see my answer below.

If your minimum SoC is set to 80%, ESS will discharge the top 20% into the grid. That is what it is designed to do.

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marekp avatar image marekp Warwick Bruce Chapman commented ·

Hi @warwick,

Can you describe the reason why ESS system would discharge the top 20% of battery energy into the grid when SOC min is set to 80%?

I would understand that discharging if there was a 80% SOC max setting.

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Warwick Bruce Chapman avatar image Warwick Bruce Chapman marekp commented ·

Because that is the minimum SoC the battery is allowed to "drop" to while the grid is there.

Ie. "ESS will not allow the Battery State of Charge to drop lower than this minimum setting of 80%. ESS will allow the top 20% of the battery to be discharged to loads (the grid included) but no more than 20% as that would reduce the SoC below 80%."

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marekp avatar image marekp Warwick Bruce Chapman commented ·

Hi @warwick

Is this setting you are talking about?

"DC-coupled PV - feed in excess"

screen-shot-2021-05-27-at-104452-pm.png

This setting is about "feeding in excess" PV DC-coupled not battery.

Not feeding excess of battery power.

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Warwick Bruce Chapman avatar image Warwick Bruce Chapman marekp commented ·

Yes, that's right. I've amended my previous statement.

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ganderpe avatar image
ganderpe answered ·

Hi,

i had the same Problem.

For 1.5 Houers the ESS draind the Battery to 20% :-(

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Happend already once before.

Fronius, Color Contol, Quattro, BYD Battery, Energymeter....

Does anybody know, why this happens?

Peter




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georgebester avatar image
georgebester answered ·

yes something is not right here as my system also has erratic behavior in the "feedback into grid" which - by using a grid code should not be allowed



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nickdb avatar image nickdb ♦♦ commented ·

Is the status of vrm "realtime"? If not (and I can't see from this screenshot) then the data could be inaccurate. Do you have energy meters and how are they configured - since "AC loads" is shown you must have a meter on that side and "AC output" enabled.

Perhaps rather open your own thread and clearly document your components and settings, since your issue is something else unrelated to this topic.

Looks like something is misconfigured.

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georgebester avatar image
georgebester answered ·

switched back the grid and cant see where 360w is going ?

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Craig Robinson avatar image
Craig Robinson answered ·

Your grid set point should be set to 0W then on your selection screen de select AC coupled feed in excess as your image shows a DC coupled PV Charge so you should have that selected and limit the feed in to just under the max of the PV charger or just set it to zero if you don't want to feed back

the meter needs to be on the AC input side to be able to manage grid power and feed in


Try this first a I had a similar experience and tried setting the grid set point to all sorts of values ie if -50W dc feed back to the grid if 50W it would start charging the battery from the grid although only a small amount



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sean-lepoidevin avatar image
sean-lepoidevin answered ·

Hi, was there any solution to the battery discharging into the grid? We have a site experiencing the same thing.

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wim-immelman avatar image
wim-immelman answered ·

I have the same problem where my battery is being drained into the grid.

I have a simple system (25kWh battery, 3x5kVA Multiplus-II inverters, 3x MPPT with 15kW solar panels).

Even at night, I occasionally will find my batteries being drained into the grid when there should not be any need for it. I've tweaked the Grid SetPoint anything between 0 and 400W but that does not seem to fix this permanently. The ESS assistant baffles me sometimes. I really want to use it, but these types of issues make it difficult, as I'm actually paying for energy being fed back into the grid (using a pre-paid electricity meter that always counts one way).

Similarly, the constant bits of energy being fed back to grid as it's trying to equalize is frustrating - sometimes it will take 10 minutes for the grid value to show a positive number after loads change.


Any insight from Victron staff would be greatly appreciated.


Thanks

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