Tesla model 3 batt and PV INV

rhino 660rhino 660 Registered Users Posts: 6
Im a solar contractor and
I live offgridand have a 24.5kw pv array with 70KWH of model s modules wired for 48v
I need more storage so  
My idea is to use a tesla model 3 battery full pack 400vdc (only $8k for 75kwh) and an sma7.7 grid tie inverter with a zero export controller. Charge it with a model 3 charger when the current battery is full 
And discharge it to cover the AC load whenever possible.
Its a way to add cheap storage to my setup if the sma will do it.
The menus in the sma allow all kinds of parameters to be adjusted. I don't see why it wont work they use the same inverter for the sunny boy storage from what i can tell the last time i installed a SBS i looked it over really good.

The AC coupled battery would give me more available power and do most of the "work"

So my question is has anyone ever hooked a 400v battery into a PV inverter?

The user interface on the SB im pretty sure will let me disable mppt and i can change other things that may be beneficial to a battery setup 

The zero export with an energy meter will control the output of the inverter so its not pushing 7.7kw all willie nillie lol and i have dual 8k radian's that can FSPC 

The BMS will turn on and off the pack as needed kinda like the sun. Seems simple-ish 
I would use a sunny boy storage if I could figure out how to get the battery to talk to the sunny boy storage and for SMA to allow it to work with their firmware they basically say they don't want you using anything that's not ready to be used with it from the manufacturer. And they only like non explosive chemistry (cover there ass lol)
Off grid.
 Temporary system while i build house 
8.5 kw pv, 70kwh's tesla model S batteries, 4548 xantrex 
2 60A xw cc 1 80A outback cc. 25kw diesel gen 
Looking at skybox for 20kw ac 18.5kw dc pv when done


  • mikedykemikedyke Registered Users Posts: 1
    Hi Rhino, I know this thread is little old. But I had the same idea regarding the model 3 battery. Did you make any attempt on it? It would be interesting to know.

  • Dave AngeliniDave Angelini Solar Expert Posts: 6,186 ✭✭✭✭✭
    It would be nice to hear what he did. However, that chemistry and voltage is not really legal for a home. Especially if you have insurance!


    Tesla confirmed that nearly half of all its vehicles produced last quarter are already using cobalt-free iron-phosphate (LFP) batteries.

    The information also gives us an interesting insight into Tesla’s mix of models, which is generally quite opaque.

    Over the last few years, CEO Elon Musk has said multiple times that Tesla plans to shift more electric cars to LFP batteries in order to overcome nickel and cobalt supply concerns.

    Iron phosphate (LFP) batteries, which don’t use nickel or cobalt, are traditionally cheaper and safer, but they offer less energy density, which means less efficient and shorter range for electric vehicles.

    However, they have improved enough recently that it now makes sense to use cobalt-free batteries in lower-end and shorter-range vehicles.

    It also frees up the production of battery cells with other, more energy-dense chemistries to produce more longer-range vehicles.

    Tesla already moved its Standard Range Model 3 and Model Y produced in China to LFP cells.

    Last year, Tesla also announced it is “shifting to Lithium Iron Phosphate (LFP) battery chemistry globally” for “standard range vehicles.”

    It confirmed that the automaker planned to switch the Model 3 Standard Range, also known as Model 3 Rear-Wheel-Drive, being produced in the Fremont factory to LFP cells, too.

    Now with the release of Tesla’s Q1 2022 financial results, Tesla confirmed that nearly half of all vehicles produced are now using LFP batteries:

    “Diversification of battery chemistries is critical for long-term capacity growth, to better optimize our products for their various use cases and expand our supplier base. This is why nearly half of Tesla vehicles produced in Q1 were equipped with a lithium iron phosphate (LFP) battery, containing no nickel or cobalt. Currently, LFP batteries are used in most of our standard range vehicle products, as well as commercial energy storage applications. As a result of our energy efficient motors, a Model 3 with an LFP battery pack can still achieve a 267-mile EPA range.”

    This would mean that roughly half of Tesla’s volume comes from Model 3 Rear-Wheel-Drive, the cheapest Tesla vehicle, and the Model Y Standard Range, which is only offered in China.

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