FAQ

Does OpenDTU-OnBattery work without a battery?

Yes, OpenDTU-OnBattery always worked in systems without battery.

In addition, you can activate the "solar panels only" option in the DPL (Dynamic Power Limiter) in order to achieve zero feed throttle (Nulleinspeisung) even if you do not use a battery.

Is it possible to have 2 solar panels directly on the HOYMILES and connect the other 2 inputs to the 48v battery system?

No, this is not supported. (we talk about a 4 input, two MPPT version, eg HM-1500) The HOYMILES in this setup will only "coincidentally" cover your household consumption exactly when the solar panels can provide enough power. At night this will not work **because only about 50% of the power limit can be reached (two inputs out of four are used). **

The set limit to the HOYMILES applies to the sum of all MPPTs (i.e. all inputs). This means is, on a four input system with two MPPTs, any given limit will be split equally among two MPPTs.
e.g. a limit of 400W set, HOYMILES HM-1200/1500 will expect 200W from each of the two MPTTs. So, at night when only one MPPT (two inputs) is connected to the battery, 400W/2=200W is delivered although the set limit is 400W.

The limit is then probably adjust itself and gradually/possibly(?) might still somehow get there, but honestly, we would strongly advise against it.

Keep in mind, above applies when you connect the two panels to one MPPT, and the battery to the other MPTT (HM-1500 has two MPTTs each handling two inputs).

Actually, OpenDTU-OnBattery has an embeded algorithm trying to estimate the number of active inputs and "scale" the commands given to the inverter. "Scaling" works only for inverters which have one MPTT pro Input (e.g. HM-800 and HMS-1600 models). Inverters whose MPPTs control more than one Input (e.g. HM-1500 with two MPPTs for four Inputs) cannot be scaled for the time being:

• Prerequisite #1: The total power of the inverter is higher than the number of Inputs times 10. e.g. HM-800 (two MPPTs/two Inputs) 2x10=20W, HMS-1600 (four MPPTs/four Inputs) 4x10=40W
• Prerequisite #2: Only the Inputs that deliver more than 2W will be taken into account.

Based on the above conditions, OpenDTU-OnBattery will scale the limit appropriately.

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Can OpenDTU-OnBattery handle the information of multiple Victron MPPTs?

As of Firmware 2024.03.23, OpenDTU-OnBattery supports up to two Victron MPPT charge controllers using the VE.Direct interface.

As of Firmware 2024.06.03, OpenDTU-OnBattery supports up to three Victron MPPT charge controllers on ESP32-S3-USB boards (this fiddles with the available hardware UARTs to make it possible to use a third Victron MPPT. If three MPPTs are defined int the pin mapping, you will not be able to use the SmartShunt and JK BMS battery interfaces).

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Do I need separate Victron MPPTs if I place my Solar Panels in different directions? (the infamous East/West Question)

You do not need to have separate Victron MPPTs for each direction.

For more information: https://github.com/helgeerbe/OpenDTU-OnBattery/wiki/Victron-MPPT-battery-charger#east--west--panels-with-only-one-victron

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Huawei AC charger RG4850 with CMT2300A radio board (for HMT- HMS- Series Inverters)

Using the Huawei AC charger in combination with the CMT2300A radio board (for HMT- HMS- Inverters) is supported as of the latest Firmware (stand: Sep.2024)
Please Note: Due to the fact that the ESP32 has only two SPI available, ONLY TWO OF THREE (NRF24, CMT23000, MC2515) modules can run simultanously.
The OpenDTU-OnBattery checks presence of the modules and allocates SPI to them in fixed sequence:

1. NRF24
   
2. CMT2300
   
3. HuaweiCAN (MC2515)
   

If the OpenDTU-OnBattery finds a PIN definition in the config, it assigns one of the two available SPI.
If all three modules are present, the OpenDTU-OnBattery will allocate the first two with an SPI and the third will be denied, without hanging up. If you have all three modules "present" on your PCB board, you need to disable one of them: Change your Pin-Out configuration and define with -1 the pins of the module you want to have disabled.

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Can OpenDTU-OnBattery Dynamic Power Limiter control more than one Inverter?

Yes!
As of Release 2024.11.20 OpenDTU-OnBattery can dynamically adjust the power output of many inverters
(Releases before 2024.11.20 can dynamically adjust the power output of only one inverter).

For older releases before 2024.11.20 there are alternatives:

Note: Member @genmad has made available a Test-script to handle many inverters, using a Shelly PRO 3EM (actually, any Shelly with API Gen.2 is suitable to run the script): shellyAPIGen2AndAboveScripts

I am currently operating two OpenDTUonBattery with Dynamic Power Limiter on two 800W (HM-800) Inverters without batteries. So far it's working quite well and the controllers don't oscillate. Only when there are clouds and frequent changes between sun and shade does the regulation go off.
Also ich betreibe zwei OpenDTU-OnBattery Steuerungen mit aktiviertem Dynamic Power Limiter (Nulleinspeisung) für zwei 800W Balkonkraftwerte (HM-800) momentan noch ohne Akkus. Das läuft bislang ganz gut und die Regler schwingen sich auch nicht auf.
Nur wenn Wolken kommen und oft zwischen Sonne und Schatten wechselt, dann geht die Regelung ab.
One Inverter and OpenDTUonBattery for each of the three electricity Phases (L1,L2,L3). Each Inverter is controlled by one OpenDTUonBattery. I have one DTU on Phase L1 and one on Phase L2, (these 2 phases make up the lion's share of the continuous load) and only let the respective DTU see this phase in the Shelly3EM (/emeter/0 and /emeter/1), this is a way of preventing unwanted oscillations
Jeder WR wird von einer DTU gesteuert. Ich habe allerdings bei mir jeweils eine DTU auf L1 und L2, (diese 2 Phasen machen den Löwenanteil an dauerlast aus) und lasse die jeweilige DTU auch nur diese Phase im Shelly3EM sehen (/emeter/0 und /emeter/1), vielleicht ist das ja eine Moeglichkeit, ungewollte Schwingereien zu unterbinden.

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[genmad] https://github.com/helgeerbe/OpenDTU-OnBattery/discussions/830#discussioncomment-9014179

Also ich habe das "steuern" des Leistungsbedarfs auf verschiedene virtuelle Leistungsmesser ausprobiert und es geht. Und hier die Einschränkungen dafür:
ShellyPro3EM wird benötigt ( Shelly 3 EM geht nicht)
Man lege sich ein Script an so wie dieses was ich auch nur geklaut habe:

function GetPwr(request, response)
{
//print('Executing function open');
let EMpower = Shelly.getComponentStatus("em:0");
response.body = "PWR: " + JSON.stringify(EMpower.total_act_power); // hier noch etwas rechnen wieviel power soll von dieser Instanz benötigt werden, wieviel soll die nächste Instanz liefern ...
response.code = 200;
response.send();
}
HTTPServer.registerEndpoint('pwr1', GetPwr)
function GetPwr(request, response)
{
//print('Executing function open');
let EMpower = Shelly.getComponentStatus("em:0");
response.body = "PWR: " + JSON.stringify(EMpower.total_act_power); // hier noch etwas rechnen wieviel power soll von dieser Instanz benötigt werden, wieviel soll der vorgänger liefern ...
response.code = 200;
response.send();
}
HTTPServer.registerEndpoint('pwr2', GetPwr)
hier zwei mal dupliziert und dann kann man den via http://shellypro3em/script/2/pwr1 und http://shellypro3em/script/2/pwr2 abfragen.

Dies ist eine sehr simple Lösung die einfach die Leistung in n PWR Teile aufteilt, so wie man das gerne mache möchte. Alles Gleichmäßig, oder kaskadierend oder ... ( nur die Aufteilung muss man noch schreiben).
Nachteil dieser Lösung ist, dass es nicht die momentane mögliche Erzeugungsleistung der verschiedenen Wechselrichter und der Batterien dahinter betrachtet. Kann man aber auch machen, wird dann nur noch komplizierter, da man dann mittels mqtt die Leitungs von Solar und BAterrie holen muss und entsprechend auswerten muss. Also n nichts für Programmieranfänger.

Vorteil: man kann Phasenbedarfsunabhängig verschiedene WR steuern. Vielleicht ist das für den einen oder anderen schon eine gangbare Lösung.

And here: https://github.com/helgeerbe/OpenDTU-OnBattery/discussions/830#discussioncomment-9068160

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