The SB went in back in 2017 and later on I added a Multiplus, Cerbo GX and ET meter. I had an old analogue meter so that was not a problem (for me) if reverse-feeding.
The SB was on the essential output of the Multiplus II and it worked flawlessly, during loadshedding the Multi would manage its output via frequency shifting.The SB does have anti-islanding, so there also no problem for the first few years.
We were moved over to prepaid a few weeks ago and whilst you can set zero feedback and all that in the GX, ultimately the Multiplus now passes the grid frequency to the SB and cant throttle it anymore, so all excess goes into the meter that allows feedback, but only detects one-way , so charges me for that.
I asked two separate well-known installers that I had dealt with before about this.
The first said, no problem, just set Zero Feedback on the ESS settings. He logged in and changed it as he thought it will work. When it did not work I told him, 2 weeks later I’m still waiting for a response.
The second indicated that they had similar issues in the past, even within their personal systems and eventually removed the SB as you would then need the sunny Energy meter to try and make it work.
SMA’s documentation seem to support this. At 13 k for the meter, I ended up changing the SB out for a SmartSolar MPPT RS 450/100 as victon also states something similar in point 2.1.2 in the ESS Manual under No feed-in
This was posted on the 4x4 forum. See: https://www.4x4community.co.za/forum/showthread.php/381708-SunnyBoy-Grid-Tie-inverter-up-for-sale
Puzzles me this combination of PV and battery inverter…
Hi Richard
Please don’t cross post from other forums. There POPI Act/Privacy/Plagiarism issues and also having 2 threads on different forums isn’t the way to go.
Can you please edit your first post to point us to the forum post (on the other forum) so members can click though there if they are keen to contribute.
Thanks
In Venus 3.60 there is now the ability to limit any PV-inverter that has the correct Sunspec information models, and SMA is on the list.
I cannot say if your particular SunnyBoy will be supported. Older ones did not work correctly. I heard that some people updated firmware and got it working. You also have to configure modbus on the PV-inverter and you have to set it up to do limiting using modbus (instead of their own meter). I have no idea how this works… I’m leaving it as an exercise for the reader.
Also, special support had to be built for SMA, because they break SunSpec in their implementation. Sunspec says that to apply a limit, I first write WMaxLimPct (the name of the field for the percentage power), and then I have to write WMaxLimPct_Ena (the name of the enable field) in order to make it take effect. SMA, in their wisdom, placed the Ena register in flash RAM, and then implemented a protection mechanism that locks you out if you write to flash too often… literally making it impossible to follow the spec without bricking SMA inverters.
There is an implementation now that checks if Ena is already set, and then it writes only the power limiting percentage. And that seems to work. That is to say… while SMA might work… I would far rather that you use something that supports the standard 
Has the Sunspec standard been widely adopted?
I’m sure manufacturers would like to make their products compatible but I guess this is a more recent development…
Yes, but not everyone implements all of it.
It is split into different “information models” and you get get away with literally implementing just two of them: Model 1 (which is mandatory), and model 101 or 103 (which has the power and energy data).
If you want to limit power, you must implement model 123. And you must actually follow the spec.
SMA has always broken the rules a little in some form or another, so it has either not worked at all, or needed workarounds.
Don’t all grid-tie inverters control their power by the frequency of the mains?
See: Solis-1P3.6K-4G firmware upgrade - #3 by Richard_Mackay
Yes, but you don’t have control over the frequency of the mains unless you are running off-grid.
If you are running an ESS system that is grid connected, and you want to avoid feeding excess into the grid, then you need sunspec modbus support with the relevant information models implemented.
If you are off-grid, then you can run any PV inverter you like, and if it has sunspec support great… if not, you can use an energy meter to proxy for it. And frequency scaling will take care of it.
Also, just to be complete about all this: Sunspec was extended around 2018, and there are newer more capable information models 701, 702 and 704 that does the same thing. But again, not everyone implements 704.
And some people, like SolarEdge, has their own proprietary protocol as well. Which Victron now supports.
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