Victron + enphase : battery size

Q&A and troubleshooting
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1

Hello,

I plan to buy an victron multiplus II GX 5000va and I have currently two area solar panel :

  • Area 1 : 10*375 with iq7a (so it’s 3,5kwc)
  • Area 2 : 6*375 with iq7a (2,1kwc)

If I follow victron recommandation and set one of my two area solar panel I a battery need :

  • Area 1 : 11,2kwh
  • Area : 6,7kwh

To begin I just plan to use 2 Pylontech US5000 (so it’s about 9,6kwh) and I one year a new one.

Can I connect my solar panel area 1 to ac out 1 (of course I will use victron profil on my Enphase IQ7a) of multiplus even if I have only 9.6kwh ? What is the risk ? Knowing that I really have very few power outages.

Thanks in advance for your return

2

Please read the requirements for ac-coupling

3

Hello

Yes I see that and for factor 1.0 it’s ok if I put area 1 to multiplus II go 5000 it’s ok. My question is on this part :

3.2 Lithium batteries

1,5 kWp installed AC PV power requires 4.8 kWh of battery storage:

  • 100 Ah at 48 Vdc

  • 200 Ah at 24 Vdc

  • 400 Ah at 12 Vdc

Each additional 1.5 kWp of AC PV will require an additional proportional 4.8 kWh increase in battery storage.

It’s really mandatory ? And why this requierement ? Si ce multiplus can modulate enphase production by doing frequency shifting

4

My advice as Enphase installer would be to have a minimum of 15kWh for the first and 10kWh for the second installation.

I take it that you have two Envoy’s right? I mean one for each setup.

And yes it is mandatory because the frequency switching takes time, and your solar production needs to end up somewhere without a grid connection.

Also. I myself own a large off-grid cabin in Norway and we have some pretty huge dump loads ready for when the batteries getting full.

5

I can’t give you the exact reason, but maybe someone else can help you out.

All I know is that these are minimum recommendations and more battery capacity is always better than less.

The MP2 5000 also requires at least 2 UC5000s.

And at the latest when you want to connect to solar field 2 , even the Mp2 5k will be insufficient with the factor 1 rule.

6

Hello,

Thanks for your reply, I have only one envoy but with 2 strings (one for South panel and one for Est panel, each one with an iqrelay).

My idea it’s to use one of panel area with victron ac out and leave the other in main house power.

7

Yes I will have 2 UC5000s to begin and in few month maybe 3 (in France max allow is 15 kwh without needing a specific battery storage structure)

And for factor 1 I’m only going to connect one of the two strings, not both; they’re both below 5000 kWp, so it’s fine.

8

Ok. Have you asked your installer/Enphase to enable modbus support on your envoy?

9

No yet i just find that now we have modbus on enphase.

I Will ask but I don’t known what it’s add ? Only to get solar production on victron ? For that in first time I think to add a Shelly pro 3em.