Design Considerations

Supported Configurations

  • Up to (4) Powerwall 3 units with up to (3) Powerwall 3Expansion units can be installed with Backup Switch, Backup Gateway 2, or Gateway 3
    Informational PurposesAn informational icon, calling your attention
    Note
    Backup Switch is not certified for installation in Canada; only install Powerwall 3 with Backup Gateway 2 or Gateway 3 in Canada.
  • Powerwall 3 AC-coupled solar (Tesla Solar Inverter or third party solar inverters)
  • Powerwall 3 is not yet compatible with the following:
    • Neurio remote energy meters (all metering must be performed by Backup Switch, Backup Gateway 2, Gateway 3, and/or Tesla Remote Energy Meter; see Metering Considerations for more information)
    • Other batteries (Powerwall 2, Powerwall+, or third party batteries)
    • Stacked units (Powerwall 3 must be mounted in a side-by-side configuration)
    • Non-backup systems

Powerwall 3 Solar

Powerwall 3 has an integrated inverter and 6 MPPTs, with a maximum solar input of 20 kW DC.

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Warning
It is critical that MCIs are installed on any PV system connected to Powerwall 3. MCI(s) are required for each PV string connected to Powerwall 3, even on systems where Rapid Shutdown (RSD) requirements do not apply. See the Powerwall 3 installation manual for more information.
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Warning
Where it is allowable to install only (1) MCI per string, MCI-1 must be used. See the Powerwall 3 installation manual for more information.
Informational PurposesAn informational icon, calling your attention
Note
See AC-Coupled Solar System Sizing for information about sizing AC-coupled solar (Tesla Solar Inverter or third party solar inverters) with Powerwall 3.

System Tie-in

  • Only Tesla devices are compatible with Powerwall; no third-party equipment in lieu of Backup Switch, Backup Gateway 2, or Gateway 3.
  • Up to 200 A service with Form 2S meter socket when designing with Backup Switch.
  • Backup systems must be 120/240 V single/split-phase service only.
  • Backup Gateway / Gateway 3 should be installed with either a 200 A or smaller service or (in absence of a service rating) maximum 200 A of loads downstream of Backup Gateway 2 / Gateway 3 per NEC load calculations.
  • No line-side or load-side taps for Backup Gateway 2 / Gateway 3 interconnection:
    • Line Side Tap: Connecting the Backup Gateway 2 / Gateway 3 to the line side of the main panel or service disconnect by tapping existing wiring is never allowed, according to NEC 230.82. Inherently, there are always loads downstream of the Backup Gateway 2 / Gateway 3; it is not permissible to interconnect loads to the supply side of the service disconnect (left figure). It is permissible for the Backup Gateway 2 / Gateway 3 to intercept the service feeders (right figure) because the main breaker in the Backup Gateway 2 / Gateway 3 becomes the main service disconnect.
    • Load Side Tap: Connecting the Backup Gateway 2 / Gateway 3 to the load side of the main panel or service disconnect by tapping via insulation-piercing connectors is non-standard practice and increases the possibility of issues and/or failed inspections. Connection to the Backup Gateway 2 / Gateway 3 must be a directly routed feed.
    Informational PurposesAn informational icon, calling your attention
    Note
    When using the Backup Switch as the site relay, it is permissible to interconnect the generation panel via a tap because there are no loads downstream of the generation-only panel.
  • Powerwall must not interact with (or must be completely isolated from) any other storage systems or generation sources not listed to UL 1741.
  • An overcurrent protection device (OCPD) is always utilized for Powerwall 3 tie in (705.12).
    • The default required OCPD is 60 A; Powerwall 3 can be configured with a maximum current / power output, in which case one of the following breaker sizes is required
      Table 1. Maximum Continuous Current Options
      Maximum Continuous CurrentOutput (AC)Breaker (Overcurrent Protection)

      48 A On-grid
      64 A Off-grid*

      11.5 kW On-grid
      15.4 kW Off-grid

      80*
      48 A11.5 kW (default) 60 A
      41.7 A10 kW 60 A
      31.7 A7.6 kW 40 A
      24 A5.8 kW 30 A

      *Powerwall 3 can only provide 15.4 kW when off-grid and when there is sufficient solar; when the system is on-grid, and/or when solar production is insufficient, Powerwall 3 will provide 11.5 kW. If enabling this feature, Powerwall 3 must be installed with an 80 A breaker and appropriately sized conductors.

    Warning IconA warning icon, calling your attention to a possibly risky situation
    CAUTION
    If using a fuse as the Powerwall 3 overcurrent protection device, it must be a Class RK1 Fast Acting fuse. Use one of the following fuses or equivalent:
    Fuse TypeManufacturerPart Number
    60 A Fast-Acting Fuse, Class RK1, >= 250VAC, CLFLittelfuseKLNR60
    Eaton / BussmannKTN-R-60
    Mersen / Ferraz ShawmutA2K60R
    40 A Fast-Acting Fuse, Class RK1, >= 250VAC, CLFLittelfuseKLNR40
    Eaton / BussmannKTN-R-40
    Mersen / Ferraz ShawmutA2K40R
    30 A Fast-Acting Fuse, Class RK1, >= 250VAC, CLFLittelfuseKLNR30
    Eaton / BussmannKTN-R-30
    Mersen / Ferraz ShawmutA2K30R
  • Controlled sources such as Powerwall 3 can avoid the supply rules of NEC 705.12, including the 120% rule, when panel limits are used and backfeed is limited using software (also known as a Power Control System (705.13)), so no backfeed calculation is required. See Power Control System (PCS) Features for Powerwall Systems for more information.
  • Recommend that total Powerwall supply is able to power the single largest automatic load in the backup circuit (see Backup Loads Supported per Powerwall Quantity).
  • Any/all backup load centers abide by 705.12 or 705.13 and are adequately protected with an overcurrent protection device.
  • A load center with generation and any others upstream must abide by 705.12 or 705.13.
  • Site and solar monitoring must be installed to capture overall power flow to/from the site, as well as all solar production.
  • Powerwall, Backup Gateway, and Backup Switch are rated for 10 kA of fault current. If potential fault current onsite is greater than 10 kA:
    • A J-class fuse upstream of the Backup Gateway 2 can be utilized to make the Backup Gateway 2 rated for 22 kA.
    • Backup Switch is rated for 22 kA when a minimum 22 kA main breaker is used in conjunction with the Backup Switch.
  • Gateway 3 is rated for 25 kA of fault current when installed with an Eaton CSR or BWH main breaker, or 22 kA when installed with a Square D QO main breaker.
  • Multiple Backup Gateways can be installed on a single site to accommodate sites with greater than 200A service equipment; see the Multiple Backup Gateways on a Single Site Application Note on Partner Portal.

Equipment Location

Powerwall is not installed in habitable locations.