Switch MQTT enable/disable Dynamic Power limiter

[isabido]

I am using OpenDTU with this wonderful option (Dynamic Power limiter). I would like to be able to enable and disable via MQTT for some automations in HomeAssistant that I am trying to use.

It would be a great improvement!

Thank you for your fantastic development.

[schlimmchen]

https://github.com/helgeerbe/OpenDTU-OnBattery/wiki/MQTT#power-limiter-topics

Does that satisfy your need?

[isabido]

Thank you for such a prompt response, I was looking at these options and if I am interpreting it correctly, it does not solve the need.

I really see it as simpler, publishing an enable/disable Dynamic Power Limiter switch via mqtt

Something like that?

[schlimmchen]

I don't understand... There is a topic into which you publish a value "1" or "0". The topic is "powerlimiter/cmd/mode". If the value is "1", the DPL will be disabled (and the inverter will be shut down), as if you disabled the DPL from the OpenDTU-OnBattery WebUI. If the value is "0", the DPL will operate as setup using the OpenDTU-OnBattery WebUI.

What about this does not work for you?

Thanks for the screenshot, however, I don't know what it is imitating and how to get a toggle switch working there. Make the toggle switch write "0" if enabled, and make it write "1" if disabled. That should be what you want.

[Manos1966]

Thanks for the explanations @schlimmchen
I added an extra comment in the Wiki "Dynamic Power Limiter" regarding this.
https://github.com/helgeerbe/OpenDTU-OnBattery/wiki/Dynamic-Power-Limiter

[isabido]

If I set the value to 1, the DPL is deactivated but it also turns off the inverter! I do not need that.

I need with DPL or without DPL but working at 100%. Forgive my English, I don't know if I can explain myself.

[Manos1966]

If I set the value to 1, the DPL is deactivated but it also turns off the inverter! I do not need that.

I need with DPL or without DPL but working at 100%. Forgive my English, I don't know if I can explain myself.

@isabido read the link schlimchen posted and focus on the function when value is set to "2" 😉

[isabido]

Oops, forgive my bad English, I just re-read it again with Google Translate and now I see that what I need is...

Activate DPL in the web interface, and then change between 0 (activated according to web) and 2 (DPL deactivated)

Tomorrow when the sun rises we'll try it! I'm going to create a helper BUTTON in HOMEASSISTANT, let's see if I remember how to do it!

Thank you all for the help. In any case, it would be interesting to facilitate it in future versions so that it appears directly as an entity in homeassistant.

[isabido]

It's already done, and it seems to work.

But the truth is that this involves creating an assistant with a button and two automations for the on and off position.

I think it would be an interesting improvement to publish it as an Entity directly in MQTT.

Thank you all for the support.

[Manos1966]

Great Job @isabido

Also nice to see that it is worthwhile to have the Wiki in English language (instead of German) 👍

[isabido]

When you send the parameter to value 2, the device turns off, NOT only disables the DPL. It behaves as if you were sending a 1.

[schlimmchen]

that suggest that you are not using a VE.Direct charge controller, so the OpenDTUonBattery does not know how much solar power is being produced. ist that correct?

[Manos1966]

Hi @isabido

Really what I need is to use all the maximum production to heat water as a priority, if the DPL is active as the grid balance is close to 0w, it does not start the surplus system, because it obviously does not see surpluses as the inverter is limited.

Why do you use DPL?

1. Do not use DPL
2. Send all produced electricity to the grid electricity-meter
3. You measure the electricity meter. It will show negative values. For example -400W
4. You know you are producing 400W more than what your house needs
5. Start the thermoelectric resistance with 400W
6. You electricity meter will show 0W

Some tipps: It is better to have many thermoelectric resistances of different size for example, one 250W, one 500W in order to be able to switch them on/off.
I know that in Greece you can order them and they are made to measure, they cost only 40EUR (I have two of them...)

The alternative is to use variable thermoelectric resistances that you can control per Software.
Below is one I use in a test System and it works exceptionaly well. Unfortunately they are very expensive (compared to the 40EUR I pay to have them made in Greece):

https://www.ta.co.at/en/x2-energy-management/immersion-heater-3000-w-variable-control
The EHS-R immersion heater (included with the ATON) can be controlled directly by the freely programmable controllers (UVR16x2, UVR610, ...) via PWM, with a variable output from 50 W to 3000 W. The immersion heater sends the sensor values back to the CAN-EZ3 for further utilisation or forwarding to the CAN bus or DL bus.

https://www.ta.co.at/aton/
The website has English

https://www.youtube.com/@TechnischeAlternativeRT
Video is only in German

[spcqike]

@Manos1966 he uses this 25A regulator, so it should be possible to limit the output power, shouldn't it?
https://es.aliexpress.com/item/20000003997748.html?spm=a2g0o.cart.0.0.eec37a9dSt4vWf&mp=1&gatewayAdapt=glo2esp

shouldn't it be possible, to just set the DPL to like -20W and let the regulator increase its output, whenever the grid consumption is < 0W? it would be slow, yeah, as it would need some DPL (and external regulator) cycles, but at the end it should open the DPL and consume the excess solar production.

like grid -20W -> heat 20W -> grid 0 -> DPL increases to grid -20W -> heat 40W -> grid 0W -> dpl increase .....

at least thats how i did my smart parkside charger, to charge my 20V 8Ah batterys. (with mqtt and node red)

In that case, it would be preferable to use the surplus production for the rest of the household's consumption.

what other consumption do you have, if you already have a surplus?

if it does not have a minimum of 1000W, there is almost no interest in starting it

that kind of true. 20W heating isn't much for a big water tank. but it's also better than nothing. and, if it is possible to start the automatic heating with a desired grid consumption of like -20W or -50W, why shouldn't one try it? if it works, like it does in my case, you will end up with an "open" limiter. as your load (heater) increases with every calculation cycle.

[isabido]

Thanks for the options and recommendations, but I really don't want to use the GRID value.

I have a significant limitation with the language to make myself understood. Let's see with a practical case.

Let's imagine that I have a consumption of 1Kw at home, I have a solar production of 1Kw.

If I don't start the water heater, the balance is 0kw.

But I want to use all the solar energy produced to heat some water.

So if I turn on the water heater I would have 1Kw in the water heater, 1kw of consumption at home, and therefore a network consumption of 1Kw.

In short, my priority with the surplus is not to feed the house's consumption, it is to HEAT water, even if this implies consuming energy from the electrical grid.

With the options that you are considering, I would only heat the water with the excess energy after feeding all the consumers in the home. And I don't want to do that... the priority is to heat water and when finished, return to DPL mode to avoid draining the network.

[spcqike]

but, does the DPL matter in this scenario at all?

if you don't care about "only using excess energy", and if you don't mind to consume grid energy, why not just start the heater whenever needed?

the opendtu will see, that your grid consumption jumps from 0W to like 1000W and open up the DPL, which let it produce as much pv power as possible.

maybe it's just me, but where is the difference between your wish "disable DPL with a third mode, that just set it to 100%" and my "start your heater, the DPL will follow and likely end up at 100%" in your scenario?

[Manos1966]

@isabido I understand!

The HMS-2000-4T will produce maximum 2000W electricity.
Is it a problem if all HMS-2000-4T electricity (2000W) goes to the GRID?
Why do you want to use DPL?

I have the same opinion as @spcqike

1. Do not use DPL
2. Your HMS-2000-4T produces as much electricity possible.
3. Your OpenDTU has the information on how much electricity the HMS-2000-4T produces
4. This information is also in Home Assistant
5. Use Home Assistant
   • STOP DPL
   • Wait 2 Minutes (for the HMS-2000-4T to adjust to max available production)
     - IF water temperature is below 45º AND HMS-2000-4T produces > 400W THEN START thermoelectric resistance
     - IF HMS-2000-4T produces < 400W THEN STOP thermoelectric resistance
     - IF water temperature is 65-70º THEN
     - STOP thermoelectric resistance
     - START DPL
   • Wait 10 minutes and then start again

[isabido]

No, I would like to do it like that...

First condition, do not send excesses to the GRID. (first because they don't pay me, and second that I only want to make the inverter work at the necessary power, to take care of the electronics of the inverter, in Spain the temperature in summer is very high)

If not, you will be able to add that 3 mode to enable/disable DPL.

I will set DPL to off always.

And now I will have to do some programming on an ESP32, which will do the following:

Temperature below 60º.
Start PID regulation adjusting based on "Inverter Total Power"

This way I avoid dumping into the grid, and I prioritize all the solar power to heat water.

Temperature above 60º
Start regulation PID based on "Grid Power"

This way it is not sent to the GRID, and when another consumer in the house demands energy it can be attended to.

In any case, I insist, I would like to have an entity in HA to enable/disable DPL.

[Manos1966]

Do I understand correctly that you can regulate the power of the
https://es.aliexpress.com/item/20000003997748.html?spm=a2g0o.cart.0.0.eec37a9dSt4vWf&mp=1&gatewayAdapt=glo2esp
based on the 0-10V you send?

If yes, then you may want to have a look at the Shelly Plus Dimmer 0-10V
https://www.shelly.com/en-de/products/product-overview/shelly-plus-0-10-v-dimmer

It is much easier to control the 0-10V directly from Home Assistant without the need of an ESP32

Here is a video (in German 🙈 ) using the excess electricity to charge a battery
https://www.youtube.com/watch?v=fcFFUN3Pkbo&t=4s

[isabido]

It is not a bad option to use this Shelly Dimmer, but the PID would have to run on HA or a NODERED.

The best thing would be for Shelly DIMMER himself to regulate the PID.

And the best better best!! It would be that OpenDTU integrated it, although you have to use the 0-3.3V to 0-10v or 4-20mA converter (I prefer the latter)

[Manos1966]

I would run everything on Home Assitant HA

• Data from OpenDTU regarding the HMS-2000-4T Inverter Total Power
• Shelly Plus Dimmer
• Water Temperasture
• Control of Shelly Plus Dimmer based on the conditions Inverter Total Power and Water Temperature

I do not think that OpenDTU can integrate the Water Temperature 😉 so this excludes OpenDTU

Theoretically you could run everything using SHELLY equipment, although I do not recommend this.
HA is more powerful for such tasks.
Using only SHELLY equipment you need:

• Shelly Plug or Shelly Plus 1PM
  connected to HMS-2000-4T to measure electricity
• Shelly Plus 1PM with Sensors ro measure water Temperature
• Shelly Plus Dimmer to regulate the power

[isabido]

I am going to study your option of doing it in HA (with something like https://github.com/soloam/ha-pid-controller), although I would prefer to dedicate an ESP32 to perform the PID.

Regarding temperature control in opendtu, I see no problem integrating a DS18B20 type probe.

Even so, the PID will not control by temperature, it will do so following the power of the inverter and the power consumed by the thermos. That is, if the inverter generates 1,345kW, it will adjust so that the water heater consumes those 1,345kW.

The temperature will only be used to turn OFF the PID.

Even so, I would like to be able to have control of (enable/disable) DPL, since when the water reaches 70º, I will need to activate it to not send to the GRID.

I think now we have understood each other. Thank you all for the contributions and suggestions.

[isabido]

HI @schlimmchen Have you considered the option of adding this option in a future version. The famous MODE 3 that we were discussing to enable/disable DPL.

Thanks for your time!

[schlimmchen]

See #701.

[schlimmchen]

Hm, hold on, I have second thoughts about this... For two reasons: (1) The way this mode works will make people shoot themselves in the foot because it drains the battery unconditionally. I would need to adjust the implementation such that it considers the battery stop threshold. (2) I think there is a way to achieve what you want without a special DPL mode:

You are planning to manipulate the DPL using the mode command through MQTT. In that case, it should be sufficient to put the DPL in mode 1. This will disable the DPL. The DPL will shut the inverter down, and then leave it alone. You can then set the inverter limit to 100% (also through MQTT) and enable its power production.

When your water is warm, you can reset the DPL to mode 0 through MQTT (no need to change the inverter state).

What do you think, @isabido?