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.
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?
Hi,
Just another 2 cents: I'm not expert in Lithium Batteries, but I would think twice, read more, about using them for your application. I would say Lead Acid are more adequate for backup. As far as I have understood, lithium does not like to be at 100% charge all the time, contrary to lead acid.
About your question, yes, I also think that way. I want to power a load of 2kW with same inverter and I plan on using 2x 2.4 kW modules. Ideally it should be 3 modules to match the inverter power, so I have to be carefull not exceeding the maximum power bateries can give, not the Inverter.
In may case I also have other smaller loads that will discharge them during the night, and then solar MPPT to charge in the day. Hence the idea for lithium. The grid is my backup :)
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. :)
Only problem I see is you need a bigger battery:
https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom
edit: JohnC was faster :)
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.
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)
