Application Note: Three-Phase String Inverters’ Parallel Solution Version 4.0 December 11, 2015 Yasakwa – Solectria Solar • 978-683-9700 • inverters@solectria.com • www.solectria.
This inverter application note addresses key points that should be taken into account for planning and implementation of decentralized large-scale PV plants. These recommendations are limited to inverter performance and inverter operation when multiple inverters are installed in parallel. This application note addresses inverter performance only and does not consider other system design and responsible project engineering factors, including the reliability of other system components.
Solectria’s 1000VDC three-phase string inverters (PVI 23TL, PVI 28TL and PVI 36TL) may be installed in parallel with the AC output at a single point of connection creating a low voltage building block. The low voltage blocks may then be connected directly to a 480VAC grid for the inverters without a step up transformer. The requirements for this setup are: 1. The grid’s voltage/frequency performance and variation range should follow U.S. grid standard/code. 2.
Solectria’s three-phase string inverters may be connected in parallel to one common point of connection in a single building block up to 70 inverters. Example: 1MW building block with 28kW and 36kW inverters A transformer with a minimum rating of 1.05MVA may be used with (27) PVI 36TL and (1) PVI 28TL inverters connected in parallel to a secondary window or to the low voltage side of this transformer.
