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Tibor Kocsis avatar image
Tibor Kocsis asked

Features missing : ESS limit charge power when FeedIn enable without BMS

Missing option in ESS - setting the maximum charging current or power in ESS in case of enabling feed-in. There are many installations that have lead-acid AGM batteries without BMS that have a communication port or any possibility to connect with VenusGX or CerboGx. In the event that the system is isolated or has feed-in prohibited, the DVCC function is sufficient. However, many installations have overcurrents enabled, and then the DVCC max charge inverter setting ignores it and lets all the generated energy from the PV panels into the battery, and often the internal BMS battery disconnects the battery for its own protection. If the Victron system is so expensive and high-quality, it has many disadvantages and this one is very important. This faulty function changes the batteries. I know there are a lot of smart people here, that's why I'm asking you for a suggestion or the possibility to modify it via rednode, but the best solution would be directly in ESS and GX firmware.

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larsea-dk answered ·

Current settings for mppts are ignored with feedin enabled, since it of course need to push power to the grid.

But voltage limits should not be ignored. I do though run with external control from my bms, which control the max voltage setting for the battery. Have you tried to set the max voltage in the remote consol? “Max charge voltage” in the DVCC menu? When running feedin, the system uses the battery as buffer, so you should allow a bit buffer and not set the voltage limit to 100% SOC… 95% would be better, but try adjust to find the best.

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nickdb avatar image nickdb ♦♦ commented ·

The current limits hard set on the mppts aren't ignored. Only the manually set DVCC limit, if set.

Max charge voltage is not intended to be used on a permanent basis except for specific uses (balancing issues of managed batteries, mainly pylontech). This is documented in the DVCC guide. That setting only applies to managed batteries anyway so doesn't apply to the topic.

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larsea-dk answered ·

I might have read your post wrongly the first time. Yes, the missing limit current for battery both with or without a BMS is definitely a huge issue for the Victron system if used for feedin excess. I really think Victron are able to do some programming to fix this. I have 2 mppt's supplying up to 200A, which is to high for my battery setup over longer time, so indeed this feature should be implemented.

It should just raise the current until the set battery max current is reached, then feed in excess power to grid(as per manual as I read it). And if still too much current than i.e. a multiplus can handle, the MPPT's should lower the charge current.

c1ee3c7b-ba5a-47e6-b680-8c869b3a8adf.jpegCan it be done in Node Red if Victron are not interested in fixing it??



c1ee3c7b-ba5a-47e6-b680-8c869b3a8adf.jpeg (369.9 KiB)
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Tibor Kocsis avatar image Tibor Kocsis commented ·

unfortunately, I don't have the experience to be able to set it up directly via Node-RED. I don't know exactly how the program editing works. Rather, I think it's been addressed here several times and it's still not resolved, and it's a serious shortcoming on the part of the product itself. If they would solve it, I believe that 50% of the problems with power supply and batteries would be solved.

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larsea-dk avatar image larsea-dk Tibor Kocsis commented ·

Yes, and I think it should be possible quite easily if we look at all the other features for controlling charge currents/voltages. I have widely talked quite positively about my system, but for ongrid and feedin, I actually think now that people should look in other directions. But maybe a switch to a Fronius instead og the mppts is a solution, if Victron is not handling this issue

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pedaaa avatar image pedaaa larsea-dk commented ·
i can think of 4 solutions:


1. buy a bigger battery

2. or change one MPPT to a Fronius

or, if you have external control possibilities:

3. dynamically reduce CVL via Modbus Register 2710, to meet the CCL sent by the BMS.

(BMS-CCL can be found at Register 307)


or, alternatively:

4. turn off DC-Feed-in at ESS settings, and do "manually" DC-Feed-in, via a negative Gridsetpoint. (dynamically tune Register 2700)

Nice about this solution is, that Victron now actually does respect the BMS-CCL by itself, as DC-Feed-in is switched OFF.

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stefan1967 answered ·

Have the same problem, serial driver settings are completely ignored if DC feed is on, which brings much too high current to the BMS and the BMS cuts the loading. Also node red integration is difficult, because of the issue with different device ids after Venus OS reboot on raspberry. Would like to see victron will fix both issues.

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