question

heggink avatar image
heggink asked

Looking for general expert advice and sanity check

Hey everyone,

I am in the process of building a home battery:

  • 48 280AH Lifepo4's in 3 parallel strings
  • JK BMS's
  • connected to 3 Multiplus-II 5000's, Cerbo and display, smart shunt (and anything else I may still need).

Effectively, I am copying Harold Halewijn's setup as described in his many videos on youtube (many thanks for that).

One thing I would like to do is to control the systems using hourly energy rates ie charge when the rates are low, dischare to a base level (25%?) when rate are high and use the remaining energy for the morning peak, rinse and repeat. I currently already heat my boiler during low rates using my home automation (domoticz) where I am pretty proficient in that side of the automation. It's the ESS side where I can do with some advice/help.

I would (really) like help with the following:

  1. sanity check on the overall setup
  2. configuration of the entire system (above and beyond Harold's videos)
  3. help on how to control the system to achieve the schedule I described (MQTT, SSH, JSON, whatever mechanism works)

Happy to spend money on it as it's really important to get it right and maintain high WAF. Based in NL, happy to drive or receive anyone.

Let me know, many thanks in advance!

Herman

Multiplus-IIess settings
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matt1309 avatar image matt1309 commented ·

Not familiar with Harold Halewijn's but I'd just make sure you've got a fast acting fuse between those parallel lifepo4s just incase something funny happens.


(like if BMS 1 went off for some reason, then battery 2 and 3 are fully charge then BMS 1 turns suddenly turns back on and there's inrush current to battery 1, you'll want a fuse there just incase). Given flat curve of lifepo4 you should be fine especially with only 3 packs in parallel but better safe than sorry.


As Kev mentioned below Node red is exactly what you're after in terms of discharging to grid etc. However you can also go the route of managing that externally via another system.

(I personally don't like using an external system to manage this. As then you're reliant on another system, ie say you turn on "exporting" via the domoticz but then the domoticz system crashes so never turns off exporting. I personally prefer to have automation setup on GX devices using node red running on venus os large itself and then if I want to pass in external info or changes from another automation system I do it via node red just so if that external system does go down for some reason, then I've still got Node red to turn something off in the event the "off" message is never received, if that makes sense)


However if you do want to go the external system route anyway, you're spoilt for choice in terms of receiving the data. There's MQTT, modbus TCP on top of node red. You can even make raw python scripts (or any other language) to read data from dbus directly and then pass to external systems however you prefer if MQTT/Modbustcp aren't what you're after).

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3 Answers
mvas avatar image
mvas answered ·

For "expert advice" you could contact your local Victron Dealer.

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heggink avatar image heggink commented ·
I tried. By the looks of it, Victron is really good at selling stuff but most of the sellers don;t offer any advice. Those that do are either in the marine business (where 3 phase and flexible energy contracts are not common) or in the industry, hence my question here...
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kevgermany avatar image
kevgermany answered ·

Take a look at setting the Cerbo up with the large OS and Node-Red. Lots of information in the modifications space here.

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heggink avatar image heggink commented ·
I think that's what I end up doing and then leech teh forum for any issues I may run into.
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trantoriana avatar image
trantoriana answered ·

Hi Herman, i have a three phase system and run with ess. I use hourly dynamic pricing and load when cheap and use from battery when expensive. I keep loading prices for each percentage of battery soc and calculate the savings accordingly. Also 'lock in' power stored in battery coming from pv to be used later.


Visualisation in home assistant like:


img-20240129-065424.jpg

img-20240129-065404.jpg


Might be a bit over complicated as i like to calculate everything but seems your direction.


Drop me a line if you want to know more.


T.


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