From grid-tie to microgrid / hybrid backup

Nope its firmly screwed onto the board that I put under the inverter, i lowered the inverter to get cable to fit. Must post some more pics.

Honey… someone is wrong ON THE INTERNET! cracks fingers… this will only take a minute…

WHAT DO YOU MEAN Han fired first!?

Yes, a lot of the time “angry” and “sad” look the same from the outside…

Oh absolutely. I firmly believe that a lot of conflict is borne from fear or at least the perception that there is a threat.

The reaction of some people to the pandemic and all the things going on with that is a perfect example. I mean, I don’t want to really derail this into a debate about medicine… but it’s the most recent example for me. You are barely over the shock of how this thing derailed your life, when people start telling you there is a medicine that you MUST take. You don’t understand this thing, you are not equipped to understand this thing… heck you’re day job involves visual arts (or something suitably far removed), so this new information is perceived as a threat, which leads to distrust, fear, and then conflict.

I find it extremely useful to ask, when in a situation of conflict: What are you afraid of? What am I afraid of?



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So after some datasheet-diving, the 8 & 10 KVA Multiplus II models definitely DO NOT support parallel (or 3-phase) connection, despite what the general MP-II manual says, so the 5 + 5, probably at a later time, makes the most sense. Even more so when I realised that 5KVA = 4000W, i.e. 8000W for 2x, whereas the 8KVA is 6400W. (The 10KVA is also 8000W, but it costs quite a bit more than double the 5KVA which puts it out of my price range.)

As @rautenk said, I don’t think I can really go wrong with a MP-II 5000 right now, leaving space for #2 if needed.

Next question… I’ve been plugging my garage panels’ info into the Victron MPPT calculator, but I’m not sure I fully understand what I’m seeing.

For 4S x 3P I get the 250/60 recommended, but “Min. PV voltage @ max. temperature” still shows red. See here.

For 3S x 4P I get the 150/60 recommended, but “Min. PV voltage @ max. temperature” is still red. See here.

What should it be?

FWIW, I’m still not sure I’ll actually use the panels, or all the panels. Just want to make sure I’m understanding the tools correctly. I’m attaching the panel datasheet if anyone feels like checking the values.


I don’t see that…

Edit: Oh nevermind, it required an extra click…

It looks like a bug to me. It is supposed to light up in red if your string voltage at max temperature drops too low for the MPPT to work.

As an example, the MPPT needs 5V above battery voltage to start, and 1V above to remain active so if the Vmpp voltage drops below about 59V due to temperature, or the Voc drops below about 63V, you have a problem in most 48V systems.

OK, that makes sense, because if I push the voltage coefficient to something like -1.5%/C, I just get no compatible MPPTs, never a green number. The closest I can get is with -1.0861 %/C which ends at exactly 49V, matching the MPPT min. input. Anything more and just no results.


Making some progress after a call with the City…

The electrical COC needed for transfer needs to explicitly indicate that “a PV system is present, but has been disconnected and is not in use” in the comments.

I can then proactively apply (i.e. don’t wait for them to find me) after transfer pleading innocence and amnesty, which should sidestep the fine. Hold thumbs.

(Aside: the system wasn’t registered. If it had been, I could just apply for the modification without issues.)