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clogman avatar image
clogman asked

Will this Set-Up Work?

Hi I am considering putting in an inverter/battery solution so I can have a power back-up (on critical loads only) when the power grid goes down. With a view to future expansion with addition of solar, I am considering a Multiplus 48/5000 coupled with 2x Pylontech 3.5kWh lithium ion batteries. Is there any reason this wouldn't work? I don't really expect to use the full capacity of the inverter right as a back-up solution. Many thanks for any advice, trying to educate myself.


Multiplus-II
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clogman avatar image clogman commented ·

Thank you for all your answers. I think you guys are saying it should be OK but to be clear, my initial ESS set-up is to be (per something I read on Victron ESS design installation manual):

"Keep batteries 100% charged:

ESS can also be configured to keep the batteries fully charged. Utility grid failure is then the only time battery power is used - as a backup. Once the grid is restored, the batteries will be recharged either from the grid or from solar panels - when available."

To have the spare inverter capacity for a future solar addition, I'm proposing to buy a larger capacity inverter now, however the loads I intend to have on back-up now will be far less than the maximum the inverter is capable of delivering (4000W @25 deg C). I am proposing the 2 US3000's which can deliver a discharge current of 37A each. So I think that these could supply more or less the maximum of the inverter, which is what I gathered is important from the Victron/Pylon compatibility doc I was referred to:

"You must have the minimum number of units to supply the potential current demand of the load connected to the inverter. It is more desirable to have the inverter/charger overload than the battery."

Does this make sense?





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3 Answers
JohnC avatar image
JohnC answered ·

Hi Clog. Yes that's possible. But indeed, best to educate yourself. There's at least a couple of ways to set it up so get familiar.. Try here for starters: https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

There may be issues with sizing the inverter/batts, but if Pylon are happy then ok. Many happy hours can be spent researching all that stuff. Enjoy.. and keep asking. :)

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boekel avatar image
boekel answered ·

Only problem I see is you need a bigger battery:

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

edit: JohnC was faster :)

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Elimac avatar image
Elimac answered ·

Hi,

I think that table on the link is meant for the smaller model US2000B. I would say (please correct me if I am wrong) that if you control the load of the inverter and the solar charge adequately you can live with only two modules, even the smaller ones.

I am also thinking on the same approach, but with 2x US2000B and limiting:


a) MPPT charge to no more than 50A

b) load on the inverter no more than 2400W


Later on, when I add more modules, I can use the inverter full power.

Since I have a Venus device, I am planning in programming these conditions to NOT ignore AC and use the grid (maybe with powerassist) to not violate these conditions.

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boekel avatar image boekel ♦ commented ·

You will indeed need an ESS setup when using less modules, and not have grid-failures because than you cannot regulate inverter power.

Since @Clogman specified back-up use, you cannot reduce inverter power in such a situation (unless you make sure the critical loads cannot draw more power than allowed)

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