question

potgieter avatar image
potgieter asked

Changing solar priority in ESS

Is there a possibility To control when the batteries will be charged by the solar, maybe a specific time or when PV is that the specific high. The batteries is currently being charged in the morning as soon as PV is available and is not used by the grid I will have excess pv later in the day then The batteries can be charged

Thanks

ESS
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jimmyd avatar image jimmyd commented ·

Hi all,

(First-time writer, long time reader.)

Sorry to revive an old thread, but I have been wondering the exact same thing, but haven't been able to find a solution. (Preferably, I don't want to run any scripts, just control the system via the CCGX or remote console.)

I have a Victron Quattro 5kVA, CCGX, two SmartSolar MPPTs, and 7.4 kW lithium battery. I have over-specced the panels, meaning that on a sunny day in South Africa, there is a lot of excess PV power at midday. Also, I can feed power into the grid. Accordingly, I would like the option to set the priority as follows: 1. loads, then 2. grid, and (last of all) 3. batteries. The rationale for this is that I want to utilise the inverter at maximum (about 4 kW) to feed into the grid (for maximum RoI) and then the excess PV power (of which there will be enough at midday) will charge the batteries.

Thoughts or suggestions?

Another query (possibly off-topic but related): is there a way, using the scheduling function, the set what time the batteries charge from PV power? As far as I can tell, the scheduling option only details with battery charging from the grid.

Thanks in advance for any responses,

Jim.

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miles avatar image miles commented ·

Hi,

Did anyone end up working out a way to to set the priority to

  1. Loads (visible by direct connection or energy meter)
  2. Grid export (set to a maxium amount)
  3. then charge the batteries with whats left over ???

This Is what I want to do as well.

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shaneyake avatar image shaneyake miles commented ·

As mentioned below, if you install the Large firmware on the GX you can use node Red to do this. I am actually doing this as well as forecasting PV production so I know how much to export before charging the batteries. This is not as simple as a menu option but can be done.

https://www.victronenergy.com/live/venus-os:large

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miles avatar image miles shaneyake commented ·
Excellent,Thanks shaneyake - I Have tried to follow the intsructions to install the firmware, but no matter how many USB's or even a micro SD card with the latest firmware file on them, The Venus GX will not see the update file? any ideas what I could do?
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shaneyake avatar image shaneyake miles commented ·
Do you have this file? venus-swu-beaglebone-20210810115008-v2.80~11-large-20.swu
This is for the Venus GX, he is a link to Victron Dropbox.
https://www.dropbox.com/sh/i8ru22o4ydws1rx/AADrA_kcoaCCZ_LU6g56XSXra/v2.80~11-large-20?dl=0&subfolder_nav_tracking=1
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shaneyake avatar image shaneyake shaneyake commented ·
Also make sure usb is formatted as FAT
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miles avatar image miles shaneyake commented ·

Yes the usb is fat formatted. I’m currently running 2.72 normal firmware. I have just tried loading that latest large file you mentioned and still the Venus just won’t do anything with the file. It does see it briefly and pops up a message. “Attached storage contains a firmware image, not using for data logging.”

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shaneyake avatar image shaneyake miles commented ·
That is very strange, I had similar problem today but updated the GX to largest via menu then rebooted with USB inserted and then it showed up and I was able to upgrade to that file but on a Cerbo.
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miles avatar image miles shaneyake commented ·
Yay, I finally got it updated to the large firmware by SSH.....

Do you have have a node red file that I can look at that shows how you set it up? It is all new to me, any help will be much appreciated. not sure how we would do that here though....

Thanks so much, :)

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shaneyake avatar image shaneyake miles commented ·

screen-shot-2021-08-15-at-94744-pm.png

This is an example of possible operation.

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

The priority use for PV in this system is :

  1. Loads (visible by direct connection or energy meter)
  2. Battery charge
  3. Grid export

There is no function to export PV to the grid before the batteries are charged.

Is this really what you want to do?

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potgieter avatar image potgieter commented ·

Thank you for responding. Unfortunately the PV is used in the morning to charge the batteries and not being used by the loads, loads is currently taking energy from the grId. Only when the battery is fully charged, or there is more PV available then the loans use the PV. The priority use for PV is thus not correct on my system can you please explain to correct this.

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

It might be you have a minimum SOC set, and the battery is discharging below that point (through self discharge), or via the BatteryLife algorithm parameter.

I have a BYD battery system on my own ESS, and have less need for BatteryLife.

Is the morning PV charge going to loads once the battery SOC is above the minimum set in this ESS menu on the CCGX?


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

Here is my screenshot this shows that the batteries is not less thanthe SOC? Really don’t understand why it’s charging the batteries

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Keith Arnold avatar image Keith Arnold commented ·

I have a Multi with Fronius on AC out 1. All loads are on ACout 1+2. Zero feed-in active.

With steady state loads all is well. But in a domestic environment there are a number of loads that are on/off control. When these are on/off then all is not well at the expense of Solar and no charging (or very little) takes place.

Would really have liked to have the Grid deal with the on/off fluctuating loads, maximize Solar and take up a large chunk of the fluctuation by charging power. Adaptive control. eg when the load is detected to be fluctuating due to say 1 - 1.5 kW on/off type control then change priority could maximize solar?

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jimmyd avatar image jimmyd commented ·

Hi Guy,

Old thread, I know, sorry. Yes, I would like to change the priority order (using your numbering) to 1, 3, 2. Load first, then grid, then finally battery. Is there a way to do that?

Instead, or in addition, is there a way to schedule battery charging from PV power? (Easy to schedule battery charging from grid.) Aim: schedule the battery to be charged in the middle of the day, and export power to the grid all day (morning, middle, and afternoon).

Thanks,

Jim.

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justinq avatar image justinq jimmyd commented ·

Yep I would also welcome this feature

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Hi @JimmyD and @Justinq

There are ways to do this using the more advanced, less supported and less documented Mode 2 & Mode 3 features of ESS, either with external controls, or via the NodeRed extended functionality.

It is not supported, or documented how by Victron though, so I would encourage you to open a new question in the Community Modifications Space. From there to investigate the existing documentation, and updating your progress to that question. It is likely that others may be able to help you if you get stuck.

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michael-weser avatar image michael-weser commented ·

Hello Guy,

I have seen a somewhat strange behavior. Today was a rather cloudy, gray day with litte power from solar. The battery SOC was at 40% this morning, at the defined minimum SOC limit. The loads were powered by the grid, all power from the MPPT (~ 70W) was sent to the battery. The SOC slowly raised to ~44% when ESS kicked in, power from MPPT and battery was used to zero out the loads. The SOC quickly fell to 40%, ESS showed reason code #1 and used all solar power to charge the battery again. Why does it do that? Why not use the power form solar to support the loads and just leave the battery at 40%?


My System: MPPT 150-70, MP II 48/5000, 4xPylontech US3000 battery. Grid on ACin, grid meter connected. ESS mode optimized (without batterylife), minimum SOC set at 40%. No charging schedules set.


Thanks for any insight into this.

Michael

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nigelfxs avatar image nigelfxs michael-weser commented ·

Hi Michael

The behaviour you describe is quite normal for ESS when you are close to the programmed minimum SOC limit. My understanding is as follows:

  • When the battery is above the minimum SOC limit, the inverter is enabled and supplies power to the loads (i.e. normal operation). The battery level will increase/drop if the power supplied by the MPPT is more/less than the power required by the inverter.
  • When the battery reaches the minimum SOC limit (i.e. 40% in your example) the inverter turns off and the system goes into "passthrough" mode. You may notice that the Inverter LED on the front panel turns off in this mode). The CCGX will also show "#1". In passthrough mode, the battery does not supply any power to the loads, so all the power from the MPPT is used to recharge the battery.
  • The inverter will then turn back on when the battery increases 3% above the minimum SOC Limit (approximately). The system will then function as per normal - as described in the first point above. The "SOC + 3%" threshold is used to prevent the system from rapidly cycling between normal mode and passthrough mode.
Why not use the power form solar to support the loads and just leave the battery at 40%?

Your suggestion would require the Inverter to limit its output power dynamically - to match the incoming power from the MPPT. This method of operation requires a lot more complex control. This is possible using external control software - see references to ESS Mode 3.

Note that the "normal" ESS mode, that I described above, effectively just switches between normal operation (all loads supplied by battery) and passthrough mode (all loads supplied by grid).

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michael-weser avatar image michael-weser nigelfxs commented ·

I did an experiment and set up a charge schedule with "stop on SOC" and SOC limit set just above minimum SOC. And guess what, it does pretty much exaclty what I wanted it to do. It leaves the battery charged and uses energy from the MPPT to supply the loads. Excess energy goes into the battery. This is the perfect setting for gray winter days with little solar power. To allow the ESS to fully do it's thing, (ie when we get sunnier weather), I have to remember to disable the charging schedule. Maybe I could automate this with MQTT?

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martin24 avatar image
martin24 answered ·

I am thinking about the same problem.

In Germany you are not allowed to feed more than 70% (even lower in some cases) of the total installed peak power into the grid. So during summer time around noon there may be PV energy available that cannot be fed into the grid.

So ideally I would like to discharge the Battery during night, but not start charging when PV power becomes available but later so that this power that cannot be fed into the grid can be used to charge the battery instead of throwing it away because the battery is already fully charged when the 70% limit is reached.

So is there any possibility to start charging delayed (by time or by measured pv power or measured grid feed-in power)?



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justinq avatar image
justinq answered ·

I too am also looking at some sort of solution. I'm in Australia where the network supplier has an export limit of 5kw. I have a greatly oversized system with 6kw of PV on a fronius inverter. On a subboard I have the Victron Multigrid DC coupled with 4kw on a MPPT 250/100 (with plans to take this to 5-6kw). The fronius has a smart meter which ramps the fronius down when it senses export coming from the Victron (so as to not exceed the export limit).


I would like Loads and Export prioritised over charging battery until about 10am-2pm where the "surplus" power that can't otherwise be exported due to max being achieved can then be used to charge the battery.

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martin24 avatar image
martin24 answered ·

As far as I know it is possible to get root access to CCGX or venusGX. Then it should be possible to run a small script to enable/disable charging base on date/time.

But I have not looked into details, yet.


And of course it would be much nicer to get this functionality directly in the firmware ...

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wkirby avatar image wkirby ♦♦ commented ·

Yes, I was thinking the same sort of thing. You could probably run a cron job to write to the dbus enabling / disabling charging at whatever times you find suitable.

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

Out of the box: No. This is not a function that we currently provide in the user interface.

However, it should be possible to do with the currently available tools and controls.

One way would be to write your own control loop with a python script that sets the grid setpoint to negative whatever PV is making... times 0.88 (ish) for efficiency. This could also be done using NodeRed and/or a Raspberry Pi via modbus comms.

If you were considering this, I would suggest a new post in the modifications space to get help from other community members with modifications experience.

Reading these documents would also be a good start: https://www.victronenergy.com/live/ess:ess_mode_2_and_3

(You can use register 2902 to flip the ess mode to 3 when you want to do your own thing, and back to 1 when you want normal ess again).

https://community.victronenergy.com/questions/14801/externalexisting-node-red-connectivity-to-venus-os.html

https://github.com/victronenergy/node-red-contrib-victron

A good implementation could be something that gets included in future general releases.

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