Using Tesla model 3 or Y batteries for solar backup

mgirey

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Sep 16, 2022
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Has any of you used a Tesla model 3 or Y battery for solar backup? Either individual modules (~100V) or whole pack (~400V).

I have a battery pack already, and I have solar on the roof with Enphase IQ-8 microinverters.

I'm thinking of using this inverter:
https://www.sigineer.com/product/96...ine-for-tesla-model-3-lithium-battery-module/

And using 2 inner 25s modules in parallel (Voltage range ~92-105V according to my calculations).
Here is the manual for the above inveter:

Wondering if anyone here done something like that? Seems like in addition to the inverter/charger I also need some kind of BMS, any recommendations of what to use?

Thanks!
 

schmism

Photon Sorcerer
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Jul 13, 2020
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Central IL, USA
I don't know of any solar charge controllers that support that high of battery voltage.

You can follow the link in my sig for how to DIY AC grid charging for DC. Just string the PSU together to get the output DC voltage you need.

BMS - the only option I know of is to buy the software/hardware people have built to reverse engineer the built in Tesla one. Expensive but AFAIK the only option for tesla packs.
 

mgirey

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Sep 16, 2022
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Thank you for the reply! The inverter I linked to above has a built in charger. I don't need solar charge controllers because I am using Enphase microinverters, which output AC.

The Sigineer inverter has a neat feature where it will adjust the AC frequency to turn solar on and off depending on battery state (see attachment).

My main concern is how to do BMS and how to hook everything up together.

I think the plan is to hook up solar (AC output from microinverters, after combiner box) into AC INPUT of the battery inverter, and hook up the AC OUTPUT of the inverter to a breaker in my main panel.

According to the manual, inverter/charger will change the battery from AC on either direction (INPUT or OUTPUT). I will need the BMS to monitor for overcharging and tell inverter to shut off charging if battery is full.

Or am I missing something here?

Thanks!
 

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Ampster

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RIP Jack Rickard. I followed his videos when he believed no BMS was necessary when converting vehicles to EVs Before he passed he gave up converting EVs and evolved into high voltage hybrid solar systems.
 

mgirey

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Sep 16, 2022
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I didn’t know he passed away :( but yeah his solutions are too expensive. For my house I don’t need 400V DC; a single 100V 25kwh Tesla 3/Y module should be sufficient for my needs.
 

Ampster

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I didn’t know he passed away :( but yeah his solutions are too expensive.
His daughter and some others are trying to keep evtv alive with a few videos. I presume the store is still going.
For my house I don’t need 400V DC; a single 100V 25kwh Tesla 3/Y module should be sufficient for my needs.
I am a big Tesla fan and almost used Model S modules but they were almost as expensive as the LFP cells I used.
 

schmism

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I am a big Tesla fan and almost used Model S modules but they were almost as expensive as the LFP cells I used.
This seems to be the reoccurring theme. By the time you get a charging solution and BMS to work with the tesla pack, you've spent more than just an standard 48v LFP pack and normal BMS you can get "anywhere"
 

mgirey

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Sep 16, 2022
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I already have a Tesla battery pack from a model Y I parted out, so cost wise all I need is either a 96V inverter plus BMS or a 384V inverter and use the Tesla BMS. Plus some wires etc. I was hoping someone done it before but apparently very few people if any are using tesla 3/Y batteries.
 

niktak11

Solar Addict
Joined
Mar 14, 2021
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700
I already have a Tesla battery pack from a model Y I parted out, so cost wise all I need is either a 96V inverter plus BMS or a 384V inverter and use the Tesla BMS. Plus some wires etc. I was hoping someone done it before but apparently very few people if any are using tesla 3/Y batteries.
Sigineer has a 96V inverter that they made for Tesla modules
 

Csecrist12

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Dec 10, 2020
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43
I already have a Tesla battery pack from a model Y I parted out, so cost wise all I need is either a 96V inverter plus BMS or a 384V inverter and use the Tesla BMS. Plus some wires etc. I was hoping someone done it before but apparently very few people if any are using tesla 3/Y batteries.
So I am doing exactly what you're doing and being offered assistance by a gentleman in the Netherlands. Extremely knowledgeable guy with creative solutions to this very pack. These packs are extremely energy dense and can handle ALOT of amps. Now our houses don't use the amount a car can pull, but nevertheless, these packs are desirable.

So our solution so far: (Mind you, I'm here in the midwest, North East Indiana)

- Using an Orion BMS to control each full pack (400V) voltage and monitoring. They have systems that can go with a large number of strings and it's a completely robust system in the EV world.
- The Orion BMS would be in communication with your inverter Megarevo R12KH1NA (Including the link here and added the manual below: https://www.megarevopower.com/productinfo4.html) This inverter is a hybrid inverter split phase with a 400V battery input which is crucial. It can also have additional inverters stringed together for larger power if needed. There are a few suppliers I have talked to with pricing around the $2800-$3500 shipping and all for the large 12kw unit. I have heard mixed reviews on these units. I believe they're the same units as the Deye just simply rebranded more or less.


We haven't gone any further into it besides me, testing the packs I have because they were a little damaged, but a deal I simply could not refuse.

But I would suggest ripping off the Tesla BMS as they are riddled with problems for us DIYers and easier to have a system you can control the settings on.
 

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Csecrist12

New Member
Joined
Dec 10, 2020
Messages
43
I already have a Tesla battery pack from a model Y I parted out, so cost wise all I need is either a 96V inverter plus BMS or a 384V inverter and use the Tesla BMS. Plus some wires etc. I was hoping someone done it before but apparently very few people if any are using tesla 3/Y batteries.
Also, message me and I'd like to get you in a messaging thread with my friend who has been guiding me as he is the one with the knowledge.
 

RichardRSB

New Member
Joined
Jan 24, 2023
Messages
1
Location
Netherlands
Has any of you used a Tesla model 3 or Y battery for solar backup? Either individual modules (~100V) or whole pack (~400V).

I have a battery pack already, and I have solar on the roof with Enphase IQ-8 microinverters.

I'm thinking of using this inverter:
https://www.sigineer.com/product/96...ine-for-tesla-model-3-lithium-battery-module/

And using 2 inner 25s modules in parallel (Voltage range ~92-105V according to my calculations).
Here is the manual for the above inveter:

Wondering if anyone here done something like that? Seems like in addition to the inverter/charger I also need some kind of BMS, any recommendations of what to use?

Thanks!
I am currently working on a LR model 3 pack. You need to know a few things:
The entire LR pack has 4 modules total (2 x 25S + 2 x 23S) summed up 46P96S (96 bricks), with a nice capacity of 78kWh.
BMS: for 96S you can use OrionBMS, or Batrium. The Tesla BMS on the modules is useless. (Model S packs can use Tesla, but not model 3 21700 packs)
Charger / inverter: I will use (still awaiting delivery) a Deye 20kW HV. In the USA they are called Sol-Ark. Some models accept the input of the 400VDC from the Tesla pack, and they are available in split phase. They also accept a GEN input from an inverter, or generator.
You CAN parallel modules, but be aware you need to parallel each brick. Basically you convert to 92P25S It can be done to obtain a 100V battery, or even a 48V battery (which is insane, but possible).
In the pack EVERYTHING is aluminium, except the cans of the cells. You need to find a way to solder aluminium.
Questions? Ask. You can follow me on Instagram: Richardrsb to see how things are going here. You will find tons of information.
Greetings from the Netherlands.
 
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