Microinverters on Victron system

Speaking of. As anyone managed to get a microinverter to integrated with a Victron system.
To me, it makes sense to have a few panels covering mostly the idle load of the house, then the bigger set of panels charging the batteries and filling in for the AC spikes.

At least on my roof, I have some odd spots where I could put one or 2 panels. Would be perfect if they pushed out AC.

See @Phil.g00 's comment here: Does Enphase micro inverters play nice with frequency shifting from a multi? - Victron Community

I don’t know of any that support sunspec. Hoymiles support frequency-based scaling as far as I know (but you have to use their own management solution to grid-limit them).

Most of these systems come with their own manager box, which talks to the devices on the roof using either some kind of radio comms, or power line communication. Take Enphase for example, they use PLC, and they have a “system controller” unit that brings it all together. All we’d need is for that little box to have a Modbus-TCP interface, and to support some basic sunspec… and it would integrate like butter on hot mieliepap.

This all sounds complicated.

If you are just planning to have enough panels on them to power the base loads, is the grid limit really that important.

Its supplying AC so as a “bush fix”, one could have the output of the microinverter connected via a relay / contactor with some automation to disconnect in certain scenarios.

I have a hoymiles 1200w that I tried to connect to the sunsynk inverter and I can confirm that the sunsynk could not limit the the output through frequency shifting when grid tied ( found out a few days ago that this was due to the sunsynk mirroring the grid frequency when connected to grid). It’s however possible when in off grid mode. I eventually just created my own automation to disconnect it once my batteries were above 95 %.

As a grid tie inverter, they work well. I had 4 365w watt Canadian solar panels on it and it would consistently produce 1200w for majority of the day.

With bad winter production, I’m undecided on whether to get a few more panels to stick them on as AC coupled or to just try to sell it and try to get some solaredge optimizers to deal with a neighbors trees.

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I am not aware of an inverter that would be able to do that currently on the market. It would require double conversion, which means doubling of some expensive hardware, as well as increased losses. (Come to think about it, the axpert king series might actually be double conversion - but I doubt that they can do frequency shift)

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By adding a Carlo on the grid, you can connect a bunch of micro inverters on the input side. When the Victron see any power flowing out to grid, it will start importing to get that negative reading to zero. Effectively its only importing the power generated by the micro inverters and it will use it for loads and or charging the batteries.

My take on trying this. By the time you bought 4 panels, 4 micro inverters and a Carlo, the cost would roughly be the same as 4 panels and a 150/35.

The last option will give power during loadshedding, the first option not.

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Won’t just be Sunsynk… This is part of what makes the grid a “grid” – anything a single consumer puts on the line does not affect the frequency. All inverters will have this “problem”, which is solved by disconnecting from the grid, at which point they are in charge.

It’s interesting that Phil says (from the Victron Community post) that this was necessary for VDE 4105 certification. That should mean more and more will support it as time passes.

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I had looked at Solis and Hoymiles. Adding all the bits gets interesting very fast, hence me getting a 2nd MPPT being a 150/35, which was cheaper than a 700w Solis, for my 3 panels.

And when going with a larger array the Solis beats the microinverters by far ito total costs, it seems.

I realized that now…. After spending days with sunsynk R&D trying to figure out why the inverter would randomly disconnect the microinverter when zero export was enabled and work perfectly fine with zero export disabled. They could not frequency shift but rather just switch off to limit the export and this was done whenever any slight feedback was detected.

Oh well, my workaround worked fine for me.

You can’t frequency shift while connected to the grid, that would require shifting the frequency of the entire country, which would cause havoc if you managed to do it (also, you’d be able to help Eskom with their current shortage).

So where there isn’t a software method to limit power (eg through sunspec support of the immediate controls model), the only way to prevent export is to disconnect from the grid and to go into “micro-grid mode”.

Our own NRS097 is based on VDE AR N 4105 as well. Ours is essentially the same, just with slightly wider limits (for our slightly more “diverse” grid).

Of course, merely supporting such a grid code doesn’t make it possible to seamlessly limit while connected to the grid, as explained above. Unless they have a software method in addition to the frequency-shift method, you have to disconnect from the grid to prevent feedin.

To seamlessly tie into a Victron ESS system (if you want to limit), it needs both Sunspec support for “immediate controls” and frequency-shift support.

Soo, build it :slight_smile: