SE14.4K SetApp Enabled, 3phase 208V, with AC RSD, DC Safety Switch and, DC Fuses and AFCI Installation

May 2018

Three Phase Inverters – Design Guidelines (North America)

Background

The three phase inverters:SE14.4KUS, SE43.2KUS & SE33.3KUS, and three phase inverters with synergy technology: SE66.6KUS &

SE100KUS, differ in some of their design guidelines from other SolarEdge inverters. This document details these guidelines, which

should be followed in addition to all instructions in the SolarEdge Installation Guide.

Over-sizing

Inverter oversizing

PV inverters are designed so that generated output power will not exceed the maximum AC power. In many cases, oversizing the

inverter, i.e. having more DC power than the inverter AC power, may increase power output in lower light conditions, thus allowing

the installation of more DC power for a given inverter. DC/AC oversizing is defined as the ratio between the array STC power and

the inverter AC power.

The maximum DC/AC oversizing of all SolarEdge inverters, including the three phase inverters with synergy technology, is

135%.

Maintaining this limit ensures the lifetime of the inverter and is needed for keeping the inverter covered by its warranty. However,

the maximum oversizing is not necessarily the optimal oversizing. In many cases, you may design with lower sizing to ensure that

the inverter does not clip power. SolarEdge recommends performing proper simulations before oversizing the inverter. You may

refer to the Site Designer application to estimate the generated energy from the installation and the energy that may be lost due to

clipping.

For further details regarding inverter oversizing please refer to the document

Oversizing of SolarEdge Inverters.

String oversizing

The SE14.4KUS, SE43.2KUS and SE33.3KUS three phase inverters have three pairs of DC inputs and the three phase inverters with

synergy technology have three pairs of DC inputs per unit, allowing to connect up to 3 strings per unit without the need for an

external combiner box.

In order to reach 135% inverter oversizing without connecting more strings than inputs, these inverters support higher string power

subject to a few conditions. The table below summarizes the string power oversizing supported and the conditions required:

SE14.4KUS, 43.2KUS

SE33.3KUS, SE66.6KUS, SE100KUS

Number of strings connected per unit

Maximum power difference between the

strings

Up to 1,000W

Up to 2,000W

Power optimizer model

P600/P700/P730

String oversizing

Up to 6,500W per string

Up to 15,000W per string

If the conditions specified above are not met, maximum string power is 6,000W for the SE14.4KUS & 43.2KUS, and 12,750W for the

SE33.3KUS, SE66.6KUS & SE100KUS.

When connecting these inverters with P800 power optimizer models, the regular over sizing is higher, therefor there is no extended

oversizing.

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May 2018 Three Phase Inverters – Design Guidelines (North America) Background The three phase inverters:SE14.4KUS, SE43.2KUS & SE33.3KUS, and three phase inverters with synergy technology: SE66.6KUS & SE100KUS, differ in some of their design guidelines from other SolarEdge inverters. This document details these guidelines, which should be followed in addition to all instructions in the SolarEdge Installation Guide.
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Optimizer – Inverter Allowed Distance The total cable length of the string from the extended power three phase inverter to the farthest power optimizer is 1,150ft (2,300ft from DC+ to DC- of the inverter). DC Input The extended power and commercial three phase inverters are provided with an integrated DC Safety Switch and with terminal blocks for the connection of three strings per unit, eliminating the cost of an external DC combiner box.