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jr6542 avatar image
jr6542 asked

Are you interested in controlling your hot water or other loads when there is excess solar?

Hello,

I have create a simple solution to allow the control of the hot water immersion heater based on the state of charge and / or the current grid load for a victron system. For example if the SOC is 95%+ the immersion heater kicks in, but if the kettle goes on and the draw from grid increases then it stands by. If the system has excess solar then the tank heats up before sending to grid.

The solution needs no direct wiring into the solar system to work - it relies on the VRM API.

The only potential wiring is to use pretty much any home automation device (shelly, kasa, wemo etc) to control a contactor (relay) that in turn controls a 3kw immersion heater. This is similar in complexity to wiring a simple "timer control" to the immersion.

I've developed a simple app to for manual boost / on / off and to monitor the history remotely.

I'd like to know if anyone is interested in helping in the Beta stage of this project. There's no expensive equipment to buy.

If anyone is interested or would like to know more please drop me a line here.

Cheers

Jon

<personal info removed. Moved to mods>

Hot Water Diversion
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Rob Duthie avatar image Rob Duthie commented ·

Hi

Yes i can help with that if required as i normaly wire into the spare relay contacts on a GX or Raspi and use VE configure assistant program to set the condidtions to switch on the relay at a certain SOC or excess solar etc. Which for most people i can be issue as it not quite that easy to get right as it is quirky software.

I could be done more easily using VE configure and or the GX raspi GUI but Vicrton has not done that yet like other manufactures have, as its has a spare replay to do this, but is limited. Other wise Victron gear is good and easy to use and setup, But i have noticed some chinese companies are brining out gear that is very simalar in operation and function to victron, Victron are you listening?


Regards

Rob Duthie

NZ

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3 Answers
nickdb avatar image
nickdb answered ·

@JR6542 This is somewhat borderline advertising which would see the topic closed. Perhaps detail what costs are involved, if this is a free app or do you intend charging for it.

Include a detailed overview of the solution and how it enhances a Victron system.

Enthusiasm is great but leveraging the community to test and market a paid for product is unlikely to be viewed positively.

This section in particular is about collaboration and sharing of ideas.

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jr6542 avatar image
jr6542 answered ·

Many thanks for your comment @nickdb . All good points. I should have been clearer (in my enthusiasm!) to state this is not something that is for sale. As you say, the forum is for sharing ideas and that's what I was going for here - by seeing if anyone else would like to try the system and share their ideas on how to make it better.

The automation described uses VRM's API and in my home I've leveraged this to control the hot water system and other large loads. Essentially it's simple gateway between the VRM API and existing home automation APIs.

Given the time spent - I'd love to see if it can save other people money too. To reiterate - folks are welcome to use it for free. I am interested in knowing if it works as well in other systems as it does mine.

One further point to address "how it enhances a Victron system." - Maximising solar usage by controlling the hot water immersion heater, based on SOC and load, as described (for example) without the need to purchase any specific hardware that monitors the solar system (unlike iBoost, for example).

Apologies if this is not the place to post - please do feel free to have the post moderated :-)

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nickdb avatar image nickdb ♦♦ commented ·

Thanks for clarifying. Good luck with the project.

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luka-renko avatar image luka-renko commented ·

I want to do something similar on my sailboat: I have water heater with SHELLY 1PM Mini gen3 and was thinking to use Node-Red on Cerbo to implement the basic rules when to turn on the heater (when on shore power or battery SOC is more than 50%..).

What is the benefit of using VRM API?

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nickdb avatar image nickdb ♦♦ luka-renko commented ·

@Luka Renko Sailboats are out my comfort zone, but providing there is reliable wifi (local lan, not internet), smart, DIN mounted, timers are very common these days. Most interface with node-red, read power etc and are then very easy to control with logic.

I do the same with heatpumps etc (various topics on this open on mods).

If you are comfortable with nodered the basic logic isn't difficult and you can easily switch devices based on time of day, SOC, power consumed etc. With it running locally there is no requirement for internet access, which may be problematic for a sailboat.

It is also useful for gathering telemetry that can't be sent to VRM. In my case I am able to chart sensor data and plot that via a dashboard, like so.

screenshot-2024-07-20-at-083727.png

But, that's enough hijacking of this thread.

If you have a different requirement, or are looking for idea perhaps open a new topic or have a search for similar concepts, there have been a few.

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screenshot-2024-07-20-at-083727.png (165.4 KiB)
nickdb avatar image nickdb ♦♦ luka-renko commented ·

For a localised system using the gx is faster and more granular.

The API opens it up to remote control via third party system or app. This can be challenging for mobile applications.

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iand avatar image
iand answered ·

I've tried this on my boat using assistants to switch in an immersion heater connected to ACOUT2 when there's excess solar.
The problem is that if you're using an external BMS (REC-BMS in my case) to control the Multiplus/Quattro the switching can only be done on battery voltage, not SoC. I set levels which worked when using solar only with little else going on (e.g. turn on at 53.8V (about 99% SoC), off at 53V (about 95% SoC)).

However it then also turns on when the generator is running (battery voltage is raised when charging at ~100A) even though SoC hasn't reached the limit.

It would be really helpful if BMS SoC could be used for switching when using an external BMS (it works if the Quattro is the master, but not when externally controlled).

I'm not using Node-Red because the boatbuilder is providing support and maintainance, and they just use the basic OS...

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