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How is a Powerwall wired?

jimbo69ny

Member
May 12, 2018
403
183
Ithaca NY
Hello,

I am hoping someone here has detailed knowledge of how a Tesla Powerwall is actually connected to a house, grid and loads.
1. What are the input and outputs on the powerwall itself?
2. Is the inverter inside the powerwall box or is it a separate unit?
3. I hear about the gateway, is that a separate unit as well?
4. When people have multiple Powerwalls installed, I am curious to know exactly how they are connected.

Thanks!
 

miimura

Well-Known Member
Aug 21, 2013
6,570
6,374
Los Altos, CA
1. The Powerwall is connected by a 30A double pole circuit breaker.
2. The inverter is inside the Powerwall
3. The Gateway is a separate box that contains 3 items.
  • Automatic disconnect switch
  • Neurio energy measurement device
  • Gateway computer
4. Multiple Powerwalls are connected in parallel. Each has its own circuit breaker and a communication wire daisy chained from the Gateway. I believe it is CANbus.

When the grid is up, the Gateway computer decides what the Powerwalls should do based on the settings in the app, the power flows measured by the Neurio, and the state of charge of the batteries. The Gateway computer commands charge and discharge power for each Powerwall while grid synchronized.

When the grid goes down, the disconnect switch inside the Gateway automatically opens, isolating the Powerwalls, solar, and backup panel from the grid. The Powerwalls become the micro-grid master of sorts and the solar inverters sync to it after their initial timeout from the grid loss. The Powerwalls will charge and discharge as necessary to maintain the voltage and frequency based on household loads and solar generation. When the batteries get full, they will shift the frequency to curtail the solar and when they get low, they just shut down, preserving enough energy to protect the batteries and start up again later.
 

jimbo69ny

Member
May 12, 2018
403
183
Ithaca NY
Thank you for the info. Do you know the voltage range of the battery pack? How many series/parallel cells are in a powerwall? Is there a positive and negative input on the power wall to connect a second powerwall?

I am asking because I have a house that is off grid. I use a Princeton Power inverter that is capable of on or off grid. Its ok but I LOVE the Tesla app and interface. I have no data as to what my system is doing unless I walk outside and go to my inverter.

I am currently using a Tesla 85kwh battery pack and a Tesla Rav4 EV 41kwh battery pack for home energy storage. I have an 11kw solar array. My inverter is 10kw and 11kw peak.

I am hoping that if I purchased one Tesla power wall system and gateway, I could connect one of my batteries in parallel with it to expand the storage. It would depend on the voltage range of the power wall though. If its the same as a Tesla pack, I could have all the tesla data reporting and all of the capacity that I currently enjoy.
 

gpez

Member
Apr 25, 2019
735
602
USA
Thank you for the info. Do you know the voltage range of the battery pack? How many series/parallel cells are in a powerwall? Is there a positive and negative input on the power wall to connect a second powerwall?

I am asking because I have a house that is off grid. I use a Princeton Power inverter that is capable of on or off grid. Its ok but I LOVE the Tesla app and interface. I have no data as to what my system is doing unless I walk outside and go to my inverter.

I am currently using a Tesla 85kwh battery pack and a Tesla Rav4 EV 41kwh battery pack for home energy storage. I have an 11kw solar array. My inverter is 10kw and 11kw peak.

I am hoping that if I purchased one Tesla power wall system and gateway, I could connect one of my batteries in parallel with it to expand the storage. It would depend on the voltage range of the power wall though. If its the same as a Tesla pack, I could have all the tesla data reporting and all of the capacity that I currently enjoy.

IMO the Tesla app is nice but it's just a fancy interface (and not even that complex) on top of the Neurios and battery state of charge. While I'd imagine you could extend a Powerwall in the way you described (likely voiding the warranty in the process) it's likely cheaper/easier/more scalable to plop a Powerwall like interface on top the data from a CT at each point in your system and your battery charge level.
 

miimura

Well-Known Member
Aug 21, 2013
6,570
6,374
Los Altos, CA
The battery config and voltage inside the Powerwall is irrelevant. It is a closed system. Like @gpez said above, you would be better off setting up your own consumption and generation monitoring. I know you also have BMS monitoring of your Tesla packs, so integrating that to show SOC should be easy. If you poke around some of the other threads in this Energy forum, you can see that people have used other graphing and UI systems with their own battery systems.
 

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