Multi RS Solar charging from Grid at ess mode

[Dominik]

I would expect solar to power loads first then surplus to the batteries . When solar is not enough it should use battery if it is above minimum SOC. At least that is how my old VE Bus ESS works.

Why would it first charge battery to 100% and then start using it ?

This is my other instalation with old Multi and Cerbo ESS.

[Dominik]

DVCC Is enabled but i dont have BMS communication. I measure SOC via SmartShunt.

[Frisianstar]

With dvcc you must have a bms, if not, disable dvcc, according to the dvcc manual…

From the bms dvcc receive data about Charge Voltage and Current Limit and also Decharge Current Limit, as set in the bms.

[Dominik]

Ok DVCC Off. Do you think it can be causing issues i am describing ?

[Frisianstar]

I am quite sure of that, Victron software is complex but not clever.

[Dominik]

Okay intetesting will see then … will let you know if it did something .

[alexpescaru]

I will tell you how my Multi RS works…
I have set Minimum SOC limit (named from this on, MSOCL) to 30%.

(Situation A) During day:

• It’s not using grid.
• It uses solar to power loads.
• If excess solar, above loads, the difference charges battery.
• If not enough solar, it supplements solar with battery for powering loads and it discharge battery down to MSOCL (see Situation C).

(Situation B) During night:

• It’s not using grid.
• It discharge the battery down to MSOCL (see Situation C).

(Situation C) If SOC reaches MSOCL:

• During night:
  a) it starts using grid for powering loads.
  b) it stays there at MSOCL and it’s NOT consuming from battery
  c) it’s NOT charging from grid.
• During day:
  a) it starts using grid for powering loads.
  b) the solar will ONLY charge battery, up until reaching MSOCL+5% (in my case, 35%)
  c) once reaching MSOCL+5%, it repeats (Situation A)

It will never charge from grid, unless one of the below happens:

• the SOC is at (or falls below) MSOCL for more than 24 hours and then it charges back up to and no more than MSOCL. This is a slow charge with 10% of the set maximum charge current. (in my case I have it 65A, so with no more than 6.5A)
• the battery is in Storage mode (no consumption from battery for more than 24h) and only once per week.
• if Automatic equalization is enabled and it’s not enough solar.

Example: A lot of clouds and during a 24 hours period there was no increase from 30% limit.

[Dominik]

Thank you for explanation ! And yes that is exactly how i expect it to work . But for me MSOCL is 20%. And in a screenshot i have sent you it was still using solar only to charge battery and loads were still fed by Grid. And it was wayy above minimal SOC. It started to supply energy to loads only after battery reached 100% (exactly) . Then MPPT had to throttle down because battery was full and loads were not as high as Solar production. Which is lost energy that could have been used instead of cycling battery.

It is kind of visible on this graph. You can see smooth raise in SOC and also battery current .

[alexpescaru]

The difference from my system is that you are using a shunt.
My system is using the SOC and the current measured by BMS and Multi RS.
You have a shunt that it’s providing SOC and current measurements.

Try to disable SCS - shared current sense and SVS - shared voltage sense.
Mine are OFF.

[Dominik]

Sorry i added some picture in post above to show the behaviour a little. I have entirely disabled DVCC as recommended in few posts before.

[Dominik]

So reporting back after 3 days and it looks like it helped !

It seems the DVCC was doing problems when there was no BMS present.

Thanks everyone for help ! i will reach back in a week to let you know if still works as espected

[Dominik]

Okay guys as i promised after a week :

It works so it was DVCC which was making a mess. Thank you all for help !