question

jeepee avatar image
jeepee asked

Victron system in combination with dynamic pricing?

Hi all,

I'm new here and tried to search for the question above to no avail.

In the Netherlands it is possible to get a electricity contract based on dynamic pricing on an hourly basis (1 day forward). I'm thinking of a system where I charge a battery during very low pricing using net feed in and discharging during peak pricing (morning and evening).

Is it possible to set times where the battery will be charged with net feed in? For example 2pm if the battery is below let's say 80% SOC?

Is it possible to set timed activation where my home goes "off-grid" during peak electricity price (morning and evening) and switch this off at 10% SOC?

I've scanned the "Smartgrid II" manual for timed activation/deactivation but couldn't find something that resembled this fucntionality.

P.S.: what topic is this? offgrid doesn't seem to cover it?

Thanks,

EDIT: see https://aleasoft.com/energy-markets/epex-spot-netherlands-prices-demand/ as a data source for 1 day ahead "planning" of dynamic electricity pricing in NL.

offgridgrid parallel
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Christian Butterweck avatar image Christian Butterweck commented ·

@jeepee @Guy Stewart @mvader

The question of the topic starter is solved. Epex prices Netherlands (NL) are supported since today by my script.

I integrated the free Entso-E API so that whole europe is supported now.

See https://www.entsoe.eu/data/map/ or

https://transparency.entsoe.eu/transmission-domain/r2/dayAheadPrices/

https://github.com/christian1980nrw/victron-awattar-tibber/releases/tag/v0.8

Happy new year.

Regards

Christian

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jeepee avatar image jeepee Christian Butterweck commented ·
Hi Christian,


Very interesting! I think I understand the charging part of the script. However, does the script also push your home "off-grid -> on battery" once electricity prices hit a certain level? How do you cut the grid current to the inverter when prices are high? I guess this was solely written for a charger and not for example a Victron Multiplus II?

I could see a system without solar panels just a Multiplus II with a large battery. The multiplus would be connected between the grid and the AC loads in your home. It charges the battery with the script and force the house offgrid (discharge the battery) at high electricity prices.

Regards,

Jean-Paul

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Christian Butterweck avatar image Christian Butterweck jeepee commented ·
Yes, i am developing it with a Multiplus II. Its running under Venus OS (Raspberry PI) without additional software. Its not cutting the grid, its only charging depending the prices. Why should it be cut? If the load is too high for the inverter or the battery is empty, you still need the grid.
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jeepee avatar image jeepee Christian Butterweck commented ·
Wouldn't this just result in your battery being charged cheaply but not discharging as long as the grid is up? Mind you, I currently don't own a multiplus just trying to make the economic case for myself.
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Christian Butterweck avatar image Christian Butterweck jeepee commented ·

You need a ESS system with a energy meter. The energy meter is connected to the system so that the Multiplus knows how much energy has to be discharged. https://www.victronenergy.com/media/pg/Energy_Storage_System/en/ess-introduction---features.html

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redjudge avatar image redjudge Christian Butterweck commented ·
@Christian Butterweck:

1. Does it work also on a Cerbo GX device?

2. I tried to use your tibber code, but I see only an error on tibber. Is the code still working?

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Christian Butterweck avatar image Christian Butterweck redjudge commented ·
@redjudge Thanks for your message, yes it should work on a Cerbo.

My tibber code is only for germany, can you send me a screenshot of the error message, so i can ask the tibber support?


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redjudge avatar image redjudge Christian Butterweck commented ·

@Christian Butterweck

Bin doch aus Deutschland.

Gruß

64820013-306b-41a7-97f1-9e4011643f56.png
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Christian Butterweck avatar image Christian Butterweck redjudge commented ·

...sehr seltsam. Ich hab mal einen neuen Code erzeugt in der App. Vielleicht laufen die nach einiger Zeit ab. Versuch mal https://invite.tibber.com/z1z2om8s

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5 Answers
nickdb avatar image
nickdb answered ·

So, the product was not designed for this specific use case but you have tools that you can use to come close to what you want to do. Depending on your tech background there are development tools that can help automate a lot of this outside of the conventional management console.

You would need to use ESS (even if there isn't solar) - please read up on this and follow the tutorials at professional.victronenergy.com.

ESS provides scheduled charging/discharging with some control over minimum/max discharge and charging.

There is always a little grid used, and scheduled charging is time based, it does not stop automatically if the battery is fully charged within the window.

You can use node red and create your own logic flows to manipulate the system with a greater degree of accuracy - even pulling schedules dynamically via the utility's API, if they have one.

If you use the search function here you will find many other similar discussions which will provide some context.

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jeepee avatar image jeepee commented ·

"there is always a little grid used" -> how about forcing the system into backup mode with a programmable relais? Or would this cause a lot of wear on the system?

EDIT: something like this -> https://heschen.com/products/b071xqglww but then with higher amps

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shaneyake avatar image shaneyake jeepee commented ·
You can force the inverter to disconnect from grid from NodeRed or via Aux input but it is better to just leave the system connected to grid in most cases as you will have a few milliseconds of no power everytime you connect or disconnect which can cause problems with some appliances.
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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @jeepee,

It is possible today to do this manually with the ESS scheduled charging feature.

We are also working on making this possible automatically via one of those price data feeds, but there is no timeline to that project.

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Christian Butterweck avatar image Christian Butterweck commented ·

@mvader (Victron Energy)

@Guy Stewart (Victron Community Manager)


Within the last days i created a script that is exactly doing this dynamic pricing calculation on your plannings. Maybe you can integrate it into Venus OS.

https://github.com/christian1980nrw/victron-awattar-tibber
https://community.victronenergy.com/questions/174231/script-charge-ess-systems-at-night-depending-spot.html

I could use two more Multiplus-II 48/3000/35-32 to go to 3-phase (just in case you wanna say thank you ;-) ).


Regards Christian

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ Christian Butterweck commented ·
Hi Christian, nice! I'll get the people working on this to look at your github project
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Christian Butterweck avatar image Christian Butterweck mvader (Victron Energy) ♦♦ commented ·

Thanks @mvader . I just released v0.2. ;-)

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jeepee avatar image
jeepee answered ·

Thanks for the super fast responses! I'll dig in on the keywords provided :)

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Jason - UK avatar image
Jason - UK answered ·

I am looking at using my Multiplus ESS with a IFTTT enabled smart time clock to try and control the charge times dependant on the cost of energy with my energy supplier, also connected to IFTTT. I'll be trying several solutions hopfully this weekend. I'll post my finding on the below thread once I have finished.

https://community.victronenergy.com/questions/160552/external-charge-controller-when-using-ess-assistan.html?childToView=160851#comment-160851

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Richard Norman avatar image
Richard Norman answered ·

One thing to consider rather than disconnecting during peak on the ESS is to set an negative grid set point, something like -50 to -100 watts this will typically stop a net import for a period.


Even set to zero you will only typically see a 0.0xx kWh usage, although this will depend on your grid code and the ramp up ramp down speed your allowed.

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