Skip to main content

Three phase 120/208 or 277/480 Wye w/ single-phase inverter

Standard three-phase installation measuring power coming from a power utility (grid) and from a single-phase solar-system inverter. The color coding shows 120/208V, but applies to 277/480V as well. This diagram is for a Wye system with a neutral. Refer to delta diagrams for systems without neutral.




  • Three-phase installations are set up the same as split-phase systems, except that a third voltage-tap (L3) and a third Grid CT is required to measure power flow on phase 3.
  • With multiple inverters, add one Solar CT per inverter and define a separate register for each inverter (e.g., Solar 1 and Solar 2). Adjust the register definition according to the CT that is measuring the current and the phases that the inverter feeds onto. For example, CT5 measuring current onto L2 and also feeding onto L3: Solar 2 = S5L2 + -S5L3.
  • If there are more than three single-phase inverters, it is more economical to measure the total solar output with one CT per phase.