Installation and Operation Guide SOLECTRIA® PVI 25TL-208, PVI 50TL-480 and PVI 60TL-480
DOCR-071030-A (10/7/2022)
Page 53 of 131
Figure 3-31 Transformer Configurations Permitted with Added Requirements from Installer
Figure 3-32 Transformer Configurations NOT Permitted
If the upstream transformer is a WYE on the inverter winding, the Neutral must be grounded or additional
ground fault detection must be installed. The Neutral on the Utility Side (H0) and Inverter Side (X0) may
be connected internally and brought out as one terminal in the LV compartment and labeled (H0X0).
Transformer short-circuit impedance (Z%) should be equal to or less than 6%.
Transformer VA rating must be at least 100% of the sum of the connected inverter VA ratings.
It is recommended that the transformer VA rating be selected
based on IEEE C57.159-2016
Guide on
Transformers for application in Distributed Photovoltaic (DPV) Power Generation Systems
. It is the
responsibility of the system designer to determine and take in account the reliability of the transformer or
other system parameters.
The transformer does not require a static shield.
The maximum number of inverters connected to a single transformer is 70.
The recommended maximum voltage-drop on the Inverter to Point of Common Coupling (to the grid) is
2% at full load – including conductor temperature considerations. Voltage drop greater than 2% may
require changing the transformer tap or as a last resort adjusting the GridMaxVolt trip point settings.
A complete and most up to date guide for transformer requirements can be found in the Application Note:
Interconnection Guidelines for Yaskawa Solectria Solar PVI Transformerless Inverters found at: