Visibility on power and energy data is needed for the Powerwall 3 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. Thus, Site meter(s) must be installed upstream of all solar production, Powerwalls, and loads.
• Metering Solar – Solar meters capture production from PV inverter(s). There must not be any loads or Powerwalls behind the Solar CTs. This would result in under- or over-estimation of solar production. In this system, Powerwall 3 performs its own Solar metering. No other Solar metering is possible, as additional solar is not supported in Powerwall 3 systems with Gateway 3.

Site Metering for Gateway 3

Gateway 3 makes metering simple with its built-in Site meter (Meter Z). Meter Z may be used for a whole home backup configuration only, with no additional steps required during installation. No additional meters can be configured as Site.