Electrical Equipment Sizing and Overcurrent Protection
Overview
This section describes the requirements for installation of multiple Powerwall units with a Backup Gateway in
North America.
Pre-Requisites for Design
Before designing a Powerwall system with more than four Powerwall units:
• AC line impedance must be measured at the installation site to ensure the utility grid connection is able to
support the desired quantity of Powerwalls. If the required grid impedance is too high, the Powerwalls may
not connect to the grid, resulting in undesirable operation. See Table 1 in this app note for required
minimum impedance values.
• Minimize Impedance:
◦ Install the Powerwalls as close as possible to the point of interconnection with the grid. The
recommended maximum wire length is 33 ft (10 m).
◦ Install wires larger than required by code between the Powerwall generation panel and the point of
interconnection with the grid. Example, if the design requires 3/0 AWG wire, use 4/0 AWG wire.
• Tesla Certified Installers should submit their multiple Powerwall system designs and measured impedance
values to Tesla for review by sending design documents to powerwalldesignreview@tesla.com. Copy your
Tesla account manager on all submissions.
• Designers must properly size overcurrent protection and loads to account for the full power potential of
multiple Powerwalls. For example, a 10-Powerwall system is capable of discharging up to 50 kW of power.
See design examples in Panel Configuration and Breaker Sizing.
• Multi-Powerwall installations may require larger Powerwall communication wire between the Backup
Gateway and the Powerwall units. Please refer to the Powerwall 2 AC / Gateway Communication Wiring
application note on communication cable requirements, as your install may require up to #16 AWG or 1.3
mm
2
wire.
• For systems between 11 to 20 Powerwalls, multiple Backup Gateways are required, as each Gateway can
only c
ontrol up to 10 Powerwall units. Please refer to the Multiple Gateways on a Single Site application
note on the Partner Portal.
• Grid impedance does not need to be measured for o-grid systems as there is no grid impedance to
measure.
Pre-Requisites for Installation
Before installing and commissioning a multi-Powerwall system:
• Plan for the commissioning process to take longer than a typical installation. It can take up to 3 minutes to
c
omplete the commissioning scan and verify process for each Powerwall, so a 10-Powerwall system can
take up to 45 minutes during this stage of commissioning.
NOTE: Do not interrupt a commissioning step, turn o the system, or unplug the communication wiring at
any time during the commissioning process.
APPENDIX H: MULTI-POWERWALL INSTALLATIONS
68Powerwall 2 AC Installation Manual
Appendix H: Multi-Powerwall Installations
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