Multi RS Solar – How to control “Maximum feed-in” limit via Node-RED

Node-RED
, , ,
1

Hi everyone,

I have one Multi RS Solar on a 3-phase grid connection.

I’m trying to control the exact “Maximum feed-in” limit that is shown in VictronConnect (see screenshot below). This is the only setting that behaves exactly the way I want:

  • Keep battery charged
  • Throttle the MPPTs when the battery is full
  • Supply power to the loads on AC-in
  • Keep feed-in around zero (or completely zero when energy prices are negative)
    feedin limit
    feedin limit1266×1000 108 KB

I have already tried:

  • Every available Victron node in Node-RED
  • Writing to /Settings/CGwacs/MaxFeedInPower, /Settings/CGwacs/DisableFeedIn, /Settings/CGwacs/AcPowerSetpoint, etc.
  • Used dbus-spy while changing the value in VictronConnect, but I cannot find the exact path/value that is being written.

When I set this value to 0 W in VictronConnect, the system does exactly what I need. I only want to change this value dynamically via Node-RED (for example to 0 W when electricity prices go negative).

Does anyone know the correct way that actually writes to this exact setting?

System info:

  • Venus OS: 3.80~11
  • Multi RS Solar firmware: 1.29
  • Grid meter: VM-3P75CT (CAN connected)
2

That value, when it’s modified, is triggering a direct write of an internal register of Multi RS.
That value is stored into the non-volatile memory (EEPROM) of the Multi RS. Writing it repeatedly it will wear out the non-volatile memory.
Although, a base line for microcontrollers EEPROM write count is about 100k write cycles per cell and supposing you will write that value 10 times a day, the first failure will be in about 25 years… Or soon. :smile:

1 Like
3

Thanks for your information i’m not going to write that much on that register. In 2027 the register will be kept at 0 because of changes in regulations in the Netherlands.

But by pointing me to registers and remembering a topic you told about writing in those registers I got it working :grinning_face_with_smiling_eyes: and much help from Gemini. I’m now able to set this register with node-red.

Thanks a lot for pointing me in the right direction.

1 Like
4

Glad that you sorted it. :+1:
Make sure that the flow is not abusing of that write.

I am curious, which is the register? By any chance 0xD09D?

5

it is register 0xD08E.

6

Right… 0xD08E, VE_REG_MULTIC_ACIN1_FEEDIN_POWER_LIMIT
Don’t know why I’ve thought of 0xD09D, VE_REG_MULTIC_MAX_FEEDIN_POWER

Wonder from where Gemini found out these, quite new registers, implemented only on the latest Multi RS firmware versions. :wink:

7

Gemini told me to go to “spymode” using “candump” changing the value in victron connect app and look what’s coming on the canbus.

To verify I changed the value again in victron connect. After that tryed to write 16 or 32 bit both didn’t change the value. Only when using cansend it changed the value.

8

Ahaaa… So not Gemini, you’ve done the “hardwork”, aka spywork. :smile:

It’s a signed 32 bit value.

You can use vreg.

vreg -c socketcan:can0 -n 0x40 -s 0xD08E sn32:-100

0x40 is the address of Multi RS, probably the same in your system.
And sn32:-100, it’s sending value -100 as signed 32 bit - you can put here your value instead of -100.

9

Nice :smiling_face_with_sunglasses: got it working that way with vreg -c socketcan:vecan1 -n 0x41 -s 0xD08E sn32:0
Somehow it’s on 0x41