zero feed is not working as expected, missing zero export script switches

[rradkov]

Hello everyone !
first of all I want to thanks to everyone who contribute to this project to be so great!

Unfortunately I have a few issues with OpenDTU DPL policies which lead me to return to the grid more than 1kW of energy for the past month.
Here is my setup:
I have generic esp32s3_usb with 8MB flash memory. Firmware 2024.09.11
HMS-2000 4T inverter.
1 Shelly EM for monitoring import/export from/to the grid
1 shelly 1pm for monitoring the HMS and in case of DTU failure to turn off the inverter.
In the beginning I was with OpenDTU and desktop device with purpose of running zero export script.
The main problem then was that the OpenDTU was not able to reconnect to the HMS each morning. Temporary solution was each morning to power cycle the DTU.
I've asked for help in OpenDTU community and they recommended to reinstall the ESP with OpenDTU-OnBattery.
In the begging all was good, DTU was able to connect to the inverter without any issues but lately I'm noticing that the configuration and settings regarding zero export is not working as expected. For the past month(September) total energy returned is more than 1,7kW which I think is a lot !

I know that usually when applying new settings to the inverter it can take up to 3 seconds but lately I'm noticing that there are more that 5 seconds before new settings is applied to the inverter. Here is few screenshots from Home assistance as evidence

Here is my current configuration:
DTU each second is gathering the information from my Shelly EM

Here is the settings for the inverter:

Here is the pulling interval

Can someone advice me which settings I should configure in order to reduce exported energy ?

Some of the settings that I'm missing here that can potentially "fix" this issue from Zero export script are:
Intermediate meter
POWERMETER_MIN_POINT
ON_GRID_FEED_FAST_LIMIT_DECREASE

Are you planning implementing those two settings soon?

[Gururom]

Deine URL Zeile zur Abfrage des Shellys 3EM ist meiner meinung nach falsch.
Da sollte stehen "http://ShellyIP/status"
Aber dafür gibts je den Testbutton unten

[rradkov]

Sorry, but OpenDTU-OnBattery is a hobbyist/enthusiast project, and we cannot guarantee that no power is exported. It's not even possible... If exporting power ist so critical, you need a piece of hardware in series with your power supply, which is able to react in realtime.

Hey I know that this is hobbyist project and there is no guarantees but my main point was if those 3 switches: Intermediate meter POWERMETER_MIN_POINT ON_GRID_FEED_FAST_LIMIT_DECREASE are implemented as in the zero export script will probably solve the issue that potentially more people will encounter.

[schlimmchen]

Well... I am not going to research what these switches mean in that third party script... Maybe if you explain them well I can tell you if something similar is in OpenDTU-OnBattery or if I think it's worth a feature request.

[rradkov]

here is the information: you've asked::

[SELECT_INTERMEDIATE_METER]

if you have an intermediate meter ("Zwischenzähler") to measure the outputpower of your inverter you can set it here. It is faster than the DTU current_power value

--- define your intermediate meter - if you don´t have one set the following defines to false to use the value from your DTU---

if your powermeter falls below POWERMETER_MIN_POINT: immediatelly decrease the limit

ON_GRID_FEED_FAST_LIMIT_DECREASE = false

if your powermeter jumps under this point, the limit will be reduced instantly. it is like a "super high priority limit change".

POWERMETER_MIN_POINT = -600

[spcqike]

I don’t see any reason for these two switches. An intermediate meter might be faster, that’s true. But the Hoymiles is as slow as it is. You can’t transmit a new limit faster than it handles it anyway.

and with our actual DPL implementation I don’t see a reason for such a min point either as we have a target and an allowed hysteresis. Our cycle time is as fast as 1-2s. So if your load shuts down and you start exporting, the next DPL cycle will decrease your limit.

[Manos1966]

@rradkov I see you are still not gettting the point...

spcqike and schlimchen may correct me, your Problem is that the HOYMILES is too slow! (not the OpenDTU-OnBattery).

Since you are really determined to find a solution, here is one option for you:

Radical Option:
According to the number you provided (1,7kWh), if we suppose that the average electricity injection is at size I calculated in my other post, you have no batteries so it occurs only during daylight, you have on average SIX TIMES per day (otherwise SIX TIMES per 24hrs) a situation where HOYMILES produces more electricity than required.
SOLUTION:
Install a SHELLY PM between HOYMILES and electricity (You already have it INSTALLED 😉 )
Install a SHELLY 3erm at Power Meter (You already have it INSTALLED 😉 )
Activate a condition on the Shelly 1PM: when the Shelly 3em is NEGATIVE by more than -xx, SHUTDOWN HOYMILES for 1 Minute!
When the HOYMILES powers up, it increases production gradually thus takes time to reach the target level and by then, there is not energy injected into the network.
This way you are safe 🥂

Since you have everything needed already installed, it is very easy 😉

[Manos1966]

Unfortunately here xxxx if you export energy to the grid, you need to follow some strict regulatory laws(only certified electrician can install PV systems) and sign a contract with electricity service provider. If PV system is not certified and you're exporting to the grid, I need to pay exported energy at the price of importing it. Also they can potentially give me a ticket for that.

Oh, I see!
The bad news: The HOYMILES are "slow" in adjusting their energy limit.
It is less of a question whether the OpenDTU-OnBattery is fast or not (of course you can improve it).
It is the issue of the HOYMILES receiving a command for a new Watt limit and how long it takes to adjust to it.

The "less bad" news:

1. We actually talk about small electricity volumes here

2. The amount of electricity that you inject to the grid is actually nuch less than you think:
   Your (and everybody's) graphs do NOT report with enough precision in order to give the correct picture.
   The electricity you pay in based on kWh = Kilowatts per hour = 1000Watts per 3600seconds
   Lets suppose your HOYMILES had -621,5 W (in your graph) at 52seconds and it took until 59second to correct it
   It took also 7 seconds to go from -621,5W up to 22W, a total of 643,5 W difference over 7 seconds
   Taking on a linear basis (for simplification - not true but, I am lazy today), the rate is (643,5 / 7) 91,9W per second
   so:
   :52 second -621,5
   :53 second -621,5 + 91,9 = -529,6
   :54 second -621,5 + 91,9 + 91,9 = -437,7
   :55 second -621,5 + 91,9 + 91,9 + 91,9 = -345,8
   :56 second -621,5 + 91,9 + 91,9 + 91,9 + 91,9 = -253,9
   :57 second -621,5 + 91,9 + 91,9 + 91,9 + 91,9 + 91,9 = -162
   :58 second -621,5 + 91,9 + 91,9 + 91,9 + 91,9 + 91,9 + 91,9 = -70,1
   :59 second +22

   So.... in total (621,5+529,6+437,7+345,8+253,9+162+70) = 2420,6 / 7 = you injected on average -345,8 per second (for seven seconds!
   How many kWh it represents = (345,8 / 1000) x 7sec / 3600sec = 0,00067 kWh
   Medium size households reached a record high of EUR0.12 Kilowatt-hour in December of 2024 (I wish we had that price in Germany...)
   So, EUR0,12 x 0,00067 kWh = my calculator can not even show this number! 😆 0,00008 EUR or 0,008cent

What I am trying to say, is:

1. I do not believe your electricity provider will make an issue if you inject into the grid 0,00067 kWh every time your HOYMILES makes an adjustment.
2. If you have to pay for it, I do not believe you should worry yourself about 0,008cent
3. I would question if your electricity provider has the means to measure this UNLESS you have an electricity meter measuring the amount of electricity you inject back to the network (our German ones do that). EVEN IF THIS HAPPENS, I do not believe it will be an issue for the amount of electricity injected.

[Manos1966]

Just a quick one: It is better to post pictures WITHOUT the Serial number of your electricity meter.
I do not really know why but, better please delete these pictures (one never knows)

Your model is a sanxing dlms S12U16
(and you have THREE ! 😨 )

And it is single phase meter so I gues they install three meters, one for each phase? 😨 🤦‍♂️

[rradkov]

well, the picture showed not only mine meter 👯

[Manos1966]

Well, unfortunately you are right, this meter does collect export data 😞
Practically, if the meter shows something starting with 1.8. it shows your consumption.
If it shows something with 2.8. it is what you export to the grid.

1.8.0 Energy import,kWh = what you are consuming
2.8.0 Energy export,kWh = what you give to the grid

and then there is more.
1.8.1 Energy import T1,kWh
1.8.2 Energy import T2,kWh
2.8.1 Energy export T1,kWh
2.8.2 Energy export T2,kWh

I understand you challenge, there seems to be a long way to go in your country:

"In our country, the first photovoltaic system on a balcony was installed in a municipal housing in Dupnitsa. The reason for this is primarily the lack of a legal framework and the still unregulated legal path.
At the moment, it is easy to install such systems on private houses, but this is not the case for multi-family residential buildings.
There, it is necessary for the homeowner, who decides to put such a system on his balcony, to have the consent of 51% of the owners of the building. Permission from the energy company serving the building is also required."

"The first photovoltaic microsystem on a balcony is already a fact in Bulgaria. It was installed in a municipal housing, where the socially poor live, in the city of Dupnitsa. It is implemented under the Sunrise project – Households producing household energy from the sun with the support of Habitat Bulgaria and the municipality of Dupnitsa. The goal is for households living in social poverty, and subsequently all others, to reduce their electricity bills. Another advantage is environmental protection."

"The practice of placing solar panels on residential balconies is now firmly established in Germany. For this reason, the first installation was installed precisely by German experts from the German Solar Energy Society (DGS)."

You may want to get a connect to this person who runs the SUNRISE Project:
The SUNRISE Project aims to spread and establish balcony power plants in Eastern and South-Eastern European countries.
Christoph Johan, photovoltaic project engineer from the German Solar Energy Society (DGS)
https://www.dgs-berlin.de/solarprojects/sunrise/?lang=en
He seems to work with Bulgaria Habitat for Humanity
https://www.habitat.org/emea/bg/city/bulgaria-habitat-humanity
so probably you could call them and ask them if they have found an easier way to install "balcony power plants" in Bulgaria.

https://fakti.bg/en/imoti/901060-they-installed-the-first-solar-panel-on-a-balcony-in-our-country-this-is-how-we-produce-our-own-electricity-video

---------Summarizing--------------------

• There are movements in your country to facilitate installation of balcony power plants (or plug-in solar devices)
• There is no legal framework (although this appears to be a major issue (as it is the case in Germany) for buldings with many home owners - Not for single homes
• There are some experts you can get in contact with to ask for more information

Considering everything I read, I am nevertheless surprised that the electricity companies are already installing such high-tech digital electricity meters which already have import/export measuring capability 👍

[Manos1966]

I do not believe you are going to have an issue with your electricity company because:

• You have a high-tech electricity meter = You do not "cheat" by making the electricity meter go "backwards" i.e. show less elecricity then what you actually consumed, which is =highly illegal (similar to the days people changed the odemeters of the cars to show less kilometers driven).
• You have a system installed to ensure "zero feed -in"
• The amount of electricity you export is "accidental" and it is so small that it is irrelevant
• You pay (if I understand correctly) even for this - although I do not believe this to be the case with your electricity meter! This was the case for some electricity meters that would add Import and Export together to one number (so you would pay the sum).

But all this is theory... I do not live in Bulgaria so, better check. 🤞

[Manos1966]

If exporting power ist so critical, you need a piece of hardware in series with your power supply, which is able to react in realtime.

I have a crazy idea which is more "opening Pandora's box" but I mention it for your future plans:
Do you have a 48V battery?
You get a HUAWEI R4850 power supply (they used to cost second-hand 40 USD, now they are over 130EUR 🤮 )
The HUAWEI R4850 can deliver from 100W to 3000W charging power to the 48V battery.
It has response time (adjusting its power) of less than two seconds!
So, with a HUAWEI R4850 in your system, any excess electricity will be immediatelly absorbed by the HUAWEI ! 😎
#1239 (comment)

[Gururom]

Ich würde als erstes das minimum powerlimit im DPL höher setzen, so 40-50watt.
So wird die Einspeisung auch nochmal geringer

[rradkov]

I was thinking that this can be the problem, but it is not... The problem here is the slow reaction of reducing the output of the inverter. That's why I suggested 3 new parameters to be added to the DPL policy