question

mike48t avatar image
mike48t asked

ESS System using grid when plenty of Solar available, and Multiplus stuck on float,

I note many have had a similar problem, but all the "remedies offered tried with no improvement"

System is 24V with CCGX , Multiplus 5000VA/24 2 x MPPT Solar chargers, BMV, 12 x OPzV600 Cells, previously connected offgrid, but now with Grid connection,

System updated to latest firmware on all components, and configure with ESS,

Sorry to be a bore with the following but most replies ask for full tech setups to help, !!

Battery capacity set to 600AH, Battery monitor enabled and with SOC Bulk Finished 85%, charge efficiency 0.80

Inverter Output V = 230, DC inputs 21, 24, 22 volts respectively

AES Enabled, (Default)

Charger

Enabled

Charge Curve Adaptive+ Battery safe

Absorb 29.6

Float 26,4

Charge Current 50A,

repeat Absorb 8 hr

ditto interval 7 days

max absorb time 8 hours

Temp comp -32.4

Virtual switch , = Do not use

Assistant ESS ( Energy storage system) with

1 Battery System set to Use OPzS or OPzV batteries

Battery capacity 600AH

Sustain during 24Hours 23.00V

After 24 hours 25.00V

Dynamic Cut off in order, 24,00 V ,, 22,50V ,, 21,10V ,, 20,00V

restart offset 0.60V

No PV inverters

VE Config,

Battery Cap 600AH

Powerassist unchecked

Lithium batteries Unchecked

Dynamic current Limter unchecked

Storage Mode Unchecked,

On CCGX the following has been set under the ESS and DVCC setting

DVCC currently off ( Disabled)

ESS

Mode Optimised ( without battery life)

Grid Metering Inverter/Charger

MIN SOC ( Unless grid fails) 70%

Limit charge power disabled

Limit inverter power disables

Grid Set Point 50W

Grid Feed in enabled ( DC coupled PV - Feed in Excess)

Feed-in limiting active, NO


The comms is provided by the VE direct



your thoughts would be greatly appreciated,










ESS
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mike48t avatar image mike48t commented ·

HI Didnt quite give all the info, i wanted to ,

Here is a 2 day graph, that shows PV power being diverted to mains when batteries need charging,

further, I have disconnected the VE Direct cables to the Solar Chargers and as you can see on the batteries reached 100% ( Full charge from the Solar)

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1601455629878.png (182.3 KiB)
laurentiupitran avatar image laurentiupitran commented ·

attached files with ESS three phase system during 2 days ; clear will see that is usage from grid , during day time when energy production is plenty and not need to take from grid....

percentage taken from grid is enuff big, around 10 percent of total usage as also enuff injected to grid....

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6 Answers
Warwick Bruce Chapman avatar image
Warwick Bruce Chapman answered ·

Please enable DVCC. Please ensure the Multi firmware is updated. Needs to be > 422. Please also ensure the MPPTs are updated. Need to be > 1.46. ESS assistant also needs to be updated.

https://www.victronenergy.com/media/pg/2556-GX_Device_Manual_Venus_GX/en/dvcc---distributed-voltage-and-current-control.html


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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Mike48t,

I had a look at the VRM history for the past 7 days on that site, and I can't see anything unusual?

The system appears to be charging the batteries from solar, running the loads from the batteries and solar, exporting a little bit of solar when the batteries are full and running the loads from the grid when the batteries are flat.

Can you have a closer look at your VRM advanced history and find a period of time recently where the system is not behaving as your describe to have a closer look at?

Did you make some changes to the configuration?

The MultiPlus is moving between the charge stages, from Bulk to Absorption, to Float. It does seem like something changed 6 days ago?


One thing I noticed is that your AC input grid voltage is VERY WEAK. It can move between 190V and 250V with only a few amps difference. I would recommend having a very close look at the AC wiring to your Multi, it might need to be improved and increased in size.

The only time I can see grid power consumption is when the battery state of charge is below the ESS threshold which seems to be set at 50%. Otherwise there is a little bit of export when the batteries are full:


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mike48t avatar image mike48t commented ·

HI thanks for the feedback, , DVCC is on, and set up as indicated for GEL ,, Firware on all except the Multiplus is up to date, ( as is the latest ESS assistant update), the current Firmware is 465 on the Multi.

To answer Guy, unfortunately I switched off the Grid feed about 6 or 7 days ago to see if it made a difference, and since then not see a repeat of the problem (as expected i guess), , I have also since the issue altered the SOC to 50% ,,, Today is the first period in last 7 Days when I seem to have optimum sun conditions and this is in for the next few days so will observe and update,

I take your point about the AC in , but this is a function of a very rural location and end of the line feed ( 25mm cable) from the Local transformer in the village about 1KM away, and this is shared with 3 other users,. I have limited the AC in Current to 8 Amps and no charging batts from the grid to minimise as much as I can the V drop,

I havent noticed the problem since I made the changes to SOC and No grid feed, however i have enabled the grid feed on Thursday last and monitor to see what happens, will advise, thanks again,


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mike48t avatar image mike48t mike48t commented ·

Interestingly today the situation has repeated and is currently showing the Multiplus on Float with 74% soc, The load as 1785 ( which will probably be stable for the next hour or so, and zero to the Grid, with the Solar input as 2300W, once the heater switches off ( in about an hour , I will update the info,

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mike48t avatar image mike48t mike48t commented ·

Here is the result approx 40 minutes later when the heater is off, and showing grid feed with Multi on Float, but battery charge is circa 74%,

Unfortunately i dont get paid for power fed to the grid, so this to me is lost power if I can get the batteries up to 100% by Sundown. normally overnight usage is approx 30% of battery capacity ( IE 100 to 70% if i can achieve fully charged)

The only change done recently is

1) Grid Feed Enabled ( to show issue)

2) SVS under DVCC enable, ( as shown in the note by warwick below)

thanks

Mike

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Warwick Bruce Chapman avatar image Warwick Bruce Chapman mike48t commented ·

Mike, did you put the VE.Direct cables back into the MPPTs. They are needed by DVCC.

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mike48t avatar image mike48t Warwick Bruce Chapman commented ·

Yes, I only did it for and effect trial, thansk,

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mike48t avatar image mike48t mike48t commented ·

Hi Guy, I havew done two things one reset the DVCC as per warwicks suggestion, which reduced incident, so on Guys Advice reset the the Float Voltage slightly lower at 26.4V ( I was a little nervous to go much lower, previously 27.4V), and since then have not noticed any re occurence, the weather has now changed with shorter sun days, and less some ( more overcast),. however the system now seems to be working as I would have expected ,,, the batteries are hovering around the 90% to 100% depending on solar availability, and grid feed has only taken place when there has been an excess of solar above the charge limited conditions, ( IE 2kw or when batteries are fully charged (,,,

Mike

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mike48t avatar image
mike48t answered ·

and now some 4 hours later, the worst possible scenario for me,

The solar is sufficient to run the house, the system is calling for power from my batteries and simultaneously feeding the solar to the grid,

I have determined the need for batteries to provide 30% capacity available for overnight use, and i Hope set accordingley, yet the solar is diverting to grid when batteries need more charge, !!

My guess is assumption that the grid is on nett balance or credit, so it has no overall effect but that is not the case given that I cant access those Tariffs,


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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ commented ·

Hi @Mike48t,

I am guessing a little here now, but in VEConfigure, in the charger tab, please change the repeated absorption time to 8 hours and the repeated absorption interval to 0.5 days.

Then please report back.

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Leslieanne avatar image
Leslieanne answered ·

Hi Mike,

Might your "problem" be as simple as voltage not dropping low enough for long enough overnight for the system to return to bulk? The system seems to be in float at the times of your concern. Your float is set to 26.4 I think, so would need to drop to 24 for some unspecified (as far as the documentation goes) period before a new bulk cycle is triggered for the multi. And when ESS is used, the mppt will just do what the multi tells it, and not always start a new cycle each day.

Cheers, Leslie Anne.

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ commented ·

I think @Leslieanne might have the solution here,

There is some documentation of this in Question 7 and Question 9 of the ESS FAQ.

But not exactly articulated.

I would suggest reducing the sustain voltage to below the point of 1.3V / 12V (so in your case 2.6V, plus some margin lets say 0.5V), so 3.1V below the float voltage.

This is done in the ESS assistant.

Then make sure you set your SOC discharge point to allow for the battery to cycle deeply enough that the voltage drops to below that 2.6V below float point.

Another alternative option would be to increase the float voltage too.

Please do this @Mike48t and report back the results. If successful, I will update that FAQ to include this situation.

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mike48t avatar image mike48t Guy Stewart (Victron Community Manager) ♦♦ commented ·

HI Guy/Leslieanne,, ,thanks for update, ok that all sounds a way forward and logical, will set up this weekend coming and advise as requested, thanks

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dgnevans avatar image
dgnevans answered ·

Where are you getting your SOC reading from the Multiplus or do you have a BMV installed. Confirm you confirm what betteries you are using.

The reason I ask this is the SOC on the mulitplus works best when charging directly from the inverter itself not from an mppt. Your voltage in your picture on the batteries shows at the float votlage. if you can send through the make model of battery we can see if there is a setting issue there. But if you do not have a BMV I would look at adding one to get the correct SOC.

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mike48t avatar image mike48t commented ·

HI, SOC from BMV , the Batteries are GEL OPZV600 Enersys Powersafe ( approx 7 years old).

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laurentiupitran avatar image
laurentiupitran answered ·

hi again,

please have a look to my attached foto, and feel free to comment:

06112020-exemplu.png

it is clear now that ESS system is using grid power when not necessary needed.....just problem of regulation; this is not happened for small amount of energy, but is more pregnant/present as power is increasing.


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