FAQ

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, OpenDTUonBattery 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, OpenDTUonBattery will scale the limit appropriately.

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Why is OpenDTU-onBattery only able to manage five inverters (instead of ten)?

and

How to change the Max Number of Inverters that OpenDTUonBattery can handle (default is 5)

Have a look here: https://github.com/helgeerbe/OpenDTU-OnBattery/wiki/Compile-your-own-Firmware-with-Visual-Studio-Code#the-most-often-raised-question

UPDATE: As of Firmware 2024.03.23 the full number of inverters is supported.

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

No ....and Yes, there are solutions:

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

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

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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 not supported at the moment https://github.com/helgeerbe/OpenDTU-OnBattery/wiki/Device-Profiles#other-information

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