ESS limit feed in with AC coupled inverter (non Fronius) on AC-IN

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deunan asked Feb 27, '24

ESS limit feed in with AC coupled inverter (non Fronius) on AC-IN

Hello,

before to make some changes to my solar system i'm trying to understand how ESS feed-in works.

I know to have a fronius inverter is the best thing but i can save some money with a different brand.

A bit of data before the questions.I can convert 13 400W panels of my off-grid system into on-grid one with max 5Kw feed-in and keep the other 9 connected to 3 150/35 solar chargers, multiplus II and 30Kwh battery.

I already have 2 ET112 (not in use yet) and since we talking about a grid tied inverter i can't use it on the AC-Out side of the Multi (if i'm not wrong).

Question number 1.

If i understand well i can use grid-point 0 to not use grid power to charge my battery. If i place the first ET122 just before the meter (load side) it will monitor what it's happening for the grid part. If the grid-tied inverter produces 1000W and my house uses 300 and the battery is not at 100%, the remaninig 700 watts are used to charge the battery. The first doubt is how that power will be managed. In the vrm i can set the ac in limit not less then 6A, 1200W so i'm having some doubts. The multi will use a different setting to use just 700W for charging? Or it will get 500W from grid plus the 700W from the other inverter?

Question 2:

Feed in limit.

I understand i can set a max power feed-in but i don't understand if it's the multi alone or combined with the other inverter and read via ET112.

Example:

Max feed-in from contract is 5Kw and i set 5kw in the cerbo. The other inverter is producing and exporting 4000W , battery is 100% so the multi can feed-in the surplus of PV. How the multi will handle it? Just procude the 1000W

"missing" or it will generate 5000W plus the other 4000W in case it's not a fronius?

Thanks in advance for any answer.

Deunan.

ac coupling feed-in limit

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Answer 1 · 2024-02-27T13:01:29Z

duivert answered · Feb 27 at 01:01 PM

hi

i have some answers on your quesions:

the multiplus can not control an ac solar inverter connected to the grid / multiplus ac in, so surplus power will always go to the grid no matter the ESS settings in the multiplus

yes! you can connect an AC inverter to the ac out! (preferably with a et112 inbetween the multiplus and the solar inverter) (you need to set this up in the ESS assistant)

in that way the multiplus can control what power goes to grid or not, and your ac solar array will still work when there is nog grid!

this also answers your question nr2 :)

"schematic" :

grid > et112 > multiplus ac in > multiplus ac out1 (critical loads) > (to whatever load/house) + et112> ac solar inverter

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deunan commented · Feb 27 at 02:11 PM

Thanks for the answer. I know i can wire the pv inverter at the ac-out of the multi, but it will not be certified if connected in that way and i will not be allowed to do feed-in to the grid.

I don't want to control the pv inverter, i'm fine it produce at max power and feed-in. But i want to know if the multi will regulate itself to produce less and meet the quota i have selected. I want to maximaxe my feed-in quota.

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duivert deunan commented · Feb 27 at 03:23 PM

ah okay, feed in rules here are a bit different :)

yes i think thats possible if you put a et112 direct at the grid entry (as gridmeter), and the other et112 on the ac pv inverter ( as pv meter)

then the system should be able to throttle down (or up) the multiplus connected DC pv in case of high feed in (as set in the cerbo feed in limit)

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