Appendix F: System Energy Metering

Visibility on power and energy data is needed for the Powerwall+ system to operate properly. An energy meter accomplishes this by measuring voltage (by voltage tap) and current (by Current Transformer, CT) at certain points in the system.

There are many possible configurations for installing metering depending on system design. However, there are two goals:
  • Metering the Site – Site meters show the overall power flow to/from a site from the Grid’s perspective. The Backup Switch performs all site metering in this system.
    Informational PurposesAn informational icon, calling your attention
    Note
    If Backup Switch is installed in a standalone meter panel downstream of the meter, do not leave any loads or solar in the panel upstream of Backup Switch. During system setup, the Backup Switch CTs are automatically configured as Site CTs and cannot be changed. No other CTs should be installed upstream, and no other CTs can be configured as Site. Backup Switch can only be used in whole home backup configurations.
  • Metering all Solar – Solar meters capture production from PV inverter(s). A solar meter is factory installed in the solar assembly, with a Solar CT factory installed around the solar assembly AC power conductor.

When the site has an additional solar inverter, an additional Solar CT must be installed to measure the inverter's production. If the additional solar inverter is within 15 ft (4.5 m) of the factory-installed Neurio meter in the Powerwall+ solar assembly, the additional Solar CT can be plugged into the factory-installed meter. Otherwise, an additional remote energy meter must be installed and the Solar CT plugged into the new meter. The following section outlines installing a Neurio remote energy meter to meter additional solar.