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borisut avatar image
borisut asked

Is the size of battery essential in a 3 phase EES system?

I plan to Building a 3 Phase EES System in Germany.

3 MP2 will be run on a 14.4 KWh Pylontech batterie.

15KWp PV will be fed in via the AC Out 1 that carry my whole house network including a max 4KW heatpump and a 11KW wallbox. I will use a Fronius 8.2.3 and 3.0.3 S.

1. Are the network cards essential for these to be integrated properly?

2. The main question is if I can add a 15 KWp via Victron DC chargers if I just use 14.4 KWP Pylontech for a start or what restrictions this could bring up?

3. What maximum grid load do I get. Are the 3x5000VA of the MP2 add up with the 11.2 VA of the Frinius converters?

Thanks for your feedback

gridsolar sizing
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3 Answers
steegergrid avatar image
steegergrid answered ·

Google Victron Pylontech guide and you will find a document which explains the questions regarding Battery sizing. It tells you the minimum battery size for your 3 MP2 5000.

But if I understand you correctly you plan to have a total of 30KWp, 15 on Fronius and 15 on dc chargers. For that 14.4 KWh seems a bit too low.

Also why do you want to connect the Fronius via AC Out 2? If you do that they would turn off when you lose the grid. Put everything on AC Out 1 unless things you want to be switched off while grid is lost.


1: I do not know what network cards you mean but Fronius communication with Cerbo GX via Network should be kept powered during grid loss


2: In Summer you would'nt be able to charge 30kw in the batterys since they accept only ca. 7KW of charge. But adding it via dc chargers should be fine.

But 15KW Fronius PV Inverters is a little much with regards to Factor 1 rule for the Batteries.


3: I do not fully understand your question. If you mean how much power you can use during gridloss the Multiplus and the Fronius would indeed add up, as long as there is enough sun...

But with 14.4KWh your Victron Inverters should be limited because it is not really enough battery for 3xMP2 5000

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borisut avatar image borisut commented ·
Thanks a lot Steergrid

ACout 1 is the correct one to choose;-)

1. On the S version of the Fronius I would require a network card for communication. If I do not want to use zero feed in do I need this communication or is the frequency control good enough?

2. How important is the factor 1 rule for the batteries if I can feed into grid alternatively?

3. The 6 batteries should be able to provide 50A each and therefore up to 300A at 48V should be 14.4 KW. I understand if I would add one more batterie that should work,or?

Greetings

Boris

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steegergrid avatar image
steegergrid answered ·

1: You still have to activate frequency control somehow please ask a fronius expert how that's done without network. Also the cerbo should have a way to monitor the PV Inverter output. Without a communication device that would be possible by a carlo gavazzi meter. There are also other things to consider when using a PV Inverter without communication, for example turning off Inverter during Synchronisation back to the grid etc.. So it is possible with some workarounds but not advised.

2: Very important unless you deactivate PV Inverter during gridloss

3: I've attached a picture on how much pylontech battery one Inverter needs. Keep in mind that the Inverter pulls more than it outputs because of efficiency losses. Also surge loads are to consider.screenshot-2022-09-08-121016.jpg


screenshot-2022-09-08-121016.jpg (114.8 KiB)
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borisut avatar image
borisut answered ·

Thanks a lot for your support steegergrid. I will then start with 8 Pylontechs US 2000B.

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