Schneider Electric XW Pro 8548 Hybrid Inverter Charger Installation Guide
- June 9, 2024
- Schneider Electric
Table of Contents
Schneider Electric XW Pro 8548 Hybrid Inverter Charger
Product Information
The XW Pro AC Coupling Solutions Guide is a user manual provided by Schneider Electric. The guide provides information and instructions on designing an AC coupled installation using XW Pro battery inverters and PV inverters. It is intended for use by qualified personnel who have training, knowledge, and experience in installing electrical equipment and applying all applicable installation codes.
Product Usage Instructions
- Before attempting to install, operate, service or maintain the XW Pro AC Coupling Solutions, it is important to read the instructions carefully and become familiar with the device. The user manual contains important safety information that should be followed to avoid personal injury or damage to the equipment.
- Only qualified personnel should install, operate, service, and maintain electrical equipment. A qualified person is one who has skills and knowledge related to the construction, installation, and operation of electrical equipment and has received safety training to recognize and avoid the hazards involved. If you are unsure whether you are qualified to use this product, please seek assistance from a qualified electrician or contact Schneider Electric for more information.
- The XW Pro AC Coupling Solutions Guide provides detailed instructions on designing an AC coupled installation using XW Pro battery inverters and PV inverters. It is important to follow these instructions carefully to ensure proper installation and operation of the equipment. For country-specific details or further assistance, please contact your local Schneider Electric Sales Representative or visit the Schneider Electric Solar Business website at https://solar.schneider-electric.com.
Safety Information
Important Information
Read these instructions carefully and look at the equipment to become
familiar with the device before trying to install, operate, service or
maintain it. The following special messages may appear throughout this
documentation or on the equipment to warn of potential hazards or to call
attention to information that clarifies or simplifies a procedure.
- The addition of either symbol to a “Danger” or “Warning” safety label indicates that an electrical hazard exists which will result in personal injury if the instructions are not followed.
- This is the safety alert symbol. It is used to alert you to potential personal injury hazards. Obey all safety messages that follow this symbol to avoid possible injury or death.
- DANGER indicates a hazardous situation which, if not avoided, will result in death or serious injury.
- WARNING indicates a hazardous situation which, if not avoided, could result in death or serious injury.
- CAUTION indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.
- NOTICE is used to address practices not related to physical injury.
Please Note
Electrical equipment should be installed, operated, serviced, and
maintained only by qualified personnel. No responsibility is assumed by
Schneider Electric for any consequences arising out of the use of this
material. A qualified person is one who has skills and knowledge related to
the construction, installation, and operation of electrical equipment and has
received safety training to recognize and avoid the hazards involved. For more
information, see Audience.
Audience
This guide is intended for use by qualified personnel who plan to design an AC
coupled installation using XW Pro battery inverters and PV inverters.
The qualified personnel have training, knowledge, and experience in:
- Installing electrical equipment.
- Applying all applicable installation codes.
- Analyzing and reducing the hazards involved in performing electrical work.
- Installing and configuring batteries.
- Selecting and using Personal Protective Equipment (PPE).
Configuration, servicing, and maintenance must be performed by authorized service personnel only. Authorized service personnel meet the requirements for a qualified installer, plus they have received specific training from the manufacturer on servicing the XW Pro battery inverters and PV inverters. The qualified personnel must refer to XW Pro Installation Guide (document number 990- 91228 or 990-91403) for full safety information.
DANGER HAZARD OF ELECTRIC SHOCK, EXPLOSION, ARC FLASH, AND FIRE This
document is in addition to, and incorporates by reference, the relevant
product manuals for XW Pro inverter/charger. Before reviewing this document,
you must read the relevant product manuals. Unless specified, information on
safety, specifications, installation and operation is as shown in the primary
documentation received with the product. Ensure you are familiar with that
information before proceeding.
Failure to follow these instructions will result in death or serious injury.
About
Purpose This Solutions Guide provides planning information and safety guidelines for designing an AC-coupled system beyond what is available in the Installation and Owner’s guides.
Scope
- This Solutions Guide applies to XW Pro battery inverters and compatible Schneider Electric or 3rd party PV inverters.
- The information provided below does not modify, replace or waive any of the terms and conditions mentioned in the Installation and Owner’s guides, including but not limited to the limited warranty.
- This document also specifies typical XW Pro and PV inverter settings but the user must also consult the PV inverter manufacturer.
Related Documents
- XW Pro Li-Ion Battery Solution Guide (document number 990-6359)
- XW Pro Installation Guide (document number 990-91228 or 990-91403)
- XW Pro Multi-unit Design Guide (990-91373)
Introduction
Prerequisites
It is recommended to upgrade to the latest XW Pro and Conext Gateway firmware
before configuring the equipment. Consult Conext Gateway Owner’s Guide
(975-0806-01-03) and XW Pro Owner’s Guide (document number 990-91227 or
990-91402) for firmware upgrade instructions. To find the latest firmware, go
to
https://solar.schneiderelectric.com/products/inverterchargers/>yourproduct>Downloads>Firmware.
RISK OF INJURY AND EQUIPMENT DAMAGE
- To prevent battery damage in a micro-grid AC system, always use the latest firmware available for your inverter.
- If Li-ion batteries are used, ensure they have an external battery management system (BMS).
Failure to follow these instructions can result in injury or equipment damage.
Overview
When a PV inverter is connected to the AC output of a battery inverter, the
system is referred to as an AC-coupled system. In this configuration, the PV
inverter is exposed to the AC output voltage of the battery-based inverter,
which is responsible for grid forming during off-grid/backup operation. The PV
inverter injects power to the critical load panel and the AC output of the
battery-based inverter. The inverters are thus “AC-coupled” with each other
and are able to share PV solar and/or battery energy to the loads.
An example of AC Coupling with the XW Pro is shown in Figure 1. The PV system is connected to the grid through the internal relay located on the AC bus inside the XW Pro inverter. This allows power to be produced and supplied or “sold” back to the grid if it exceeds the power consumed by the critical loads. When the grid goes out of limits, the XW Pro switches to back-up and powers the critical load panel to support the loads. Thus, the XW Pro forms the grid to keep the PV inverters operating. The XW Pro switchover to back-up is almost instantaneous. In some cases, the PV inverter does not detect the transition and continues to operate without interruption. If the PV inverter detects the switch over, it will disconnect and then reconnect after re- qualifying the grid formed by the XW Pro, according to its settings.
Surplus Power in Off-Grid/Backup Modes
The most critical element of AC coupling is the use of the surplus power that
the PV system produces when operating in off-grid or backup mode. The surplus
power is the power that is not used by the loads. For instance, if the PV
inverter produces 4 kW and the load is 1 kW, there is a surplus of 3 kW
.
If there is more power being generated than can be consumed by the loads, the surplus power will flow to the XW Pro and will be converted to DC power which flows into the battery. Once the battery approaches full charge, power generation by the PV inverter must be curtailed to maintain the balance between generation and consumption. As the battery bank approaches full charge or its charge voltage, charge SOC, or current limits, XW Pro curtails PV inverter generation by raising the AC output frequency, causing compatible PV inverters to reduce their power output. This is called Frequency Shift power curtailment.
NOTICE RISK OF EQUIPMENT DAMAGE
Follow all instructions related to AC-coupled PV sizing, battery sizing, and
charge settings in the following sections of this document. Failure to follow
these instructions can result in equipment damage.
Planning and Installation
Supported Architectures
XW Pro inverters use Frequency Shift to regulate battery charge current coming
from AC coupled PV. PV inverters used in AC coupled systems are recommended to
have frequency-watt controls. Legacy inverters without frequency-watt controls
can be used with some limitations (see “Operation with Legacy PV Inverters” on
page 14 for more details).
Figure 3 and Figure 4 show two supported AC-coupling architectures by XW Pro
battery inverter:
- Critical loads are connected on the AC Out side of the XW Pro output (without external contactor)
- Critical loads are connected on the AC1 side of the XW Pro output (with external contactor)
For systems using Li-ion batteries, it is recommended to operate the XW Pro
with State of Charge Control enabled for enhanced AC coupling performance and
DC voltage regulation at high SOC. State of Charge Control can be used when a
Conext Battery Monitor or a compatible battery listed in the XW Pro Li-Ion
Battery Solution Guide (document number 990-6359) is connected to the system
.
Sizing
The XW Pro can be connected in various configurations from just a single unit
to multiple units in parallel, or in a three-phase configuration. Regardless
of the system configuration however, the maximum continuous allowable rating
of AC-coupled PV inverter(s) is the lesser of:
- 125% of maximum allowable charge power of the battery (calculated as rated continuous charge current times rated charge voltage).
- 125% of continuous rating of XW Pro inverter(s).
For example, if battery inverter is rated for 6.8 kW of continuous power at 40°C and battery pack is rated for 3.75 kW at 40°C, then the PV inverter must be no more than 125% of lesser of two which is 4.68 kW at 40°C. In three phase configurations utilizing XW Pro battery inverters, it is recommended to use three-phase PV inverters, such as the Schneider Electric CL series, in order to provide balanced power on the three phases.
AC Coupling with a Generator
NOTICE RISK OF DAMAGE TO THE GENERATOR OR PV INVERTER
In an AC-coupled system, never connect a generator to the AC2 (GEN) port of XW
Pro without an interlocked contactor to prevent parallel operation of the
generator and PV inverters. XW Pro will not be able to regulate power being
pushed by PV inverters into the AC2 (GEN) port and may backfeed AC power into
the generator. Failure to follow these instructions can result in equipment
damage.
While running a generator in an AC-coupled system, the generator provides AC
power to XW Pro and PV inverters. The PV inverter detects this (it recognizes
the generator as regular grid) and begins to inject power into the system.
However, generators are not designed to accept backfed power, so the
concurrent operation of the AC source and PV inverters must be disallowed.
While the generator is running, the PV inverter must be disconnected from the
circuit and therefore PV harvest is only possible when the generator is not
running and XW Pro is grid-forming. This can be done with an interlocked
contactor whose coil is driven by the generator output. Normally-open contacts
are placed between the generator output and the AC2 (GEN) port of the XW Pro,
and normally-closed contacts placed between the PV inverters and the load
panel.
Operation with Legacy PV Inverters
For AC-coupled systems with legacy PV inverters without frequency-watt
capability, the battery inverter will have reduced ability to regulate the
battery charge. When surplus power from AC-coupled PV charges the batteries
and the battery parameters (voltage, current or SOC) reach limits, the battery
inverter frequency is ramped up and the PV inverter will cease producing power
and disconnect. When the battery parameter which caused frequency shift drops
below the limit due to loss of PV charge power, its output frequency returns
to normal (50 or 60 Hz). This return to normal frequency causes the PV
inverter to initiate its reconnect delay timer (usually 5 minutes), and come
online. Depending on the available array power and loads, any surplus power
will be used to charge the batteries and the cycle will repeat. It is
recommended to set the Absorbtion Time limit to the minimum value to help
reduce cycling. Where possible, it is generally recommended to install smart
PV inverters with frequency-watt capability for AC coupled systems. However,
operation with legacy PV inverters can be considered for grid-tied
applications with less frequent outages.
Installing
Each PV inverter requires its own AC breaker in the panel to which it is
connected. Although there is room to add breakers for the PV inverters
directly into the XW Pro Power Distribution Panel, it is easier to install the
breakers in the AC sub panel. These breakers must be installed according to
the XW Pro Installation Guide (document number 990-91228 or 990-91403). The
sub-panel may also contain load breakers.
To install an AC-coupled system:
- Install one or more XW Pro inverters according to its Installation Guide.
- Install one or more PV inverters according to their Installation Guides, and connected to the panel that is backed up by the XW Pro battery inverters.
Recommended Settings
NOTICE RISK OF DAMAGE TO THE BATTERY OR BATTERY INVERTER
Always follow the recommended settings described below. The battery and the XW
Pro may be subject to DC over-voltage and/or over-current events in backup
power or off-grid operation. The below settings aim to achieve maximum system
stability. Failure to follow these instructions can result in equipment
damage.
The XW Pro AC coupling controls may temporarily disconnect the PV inverters,
as needed, based on battery state of charge, voltage, and the amount of power
coming from the PV system.
Table 1 Battery inverter settings
| Setting | Value | Notes |
|---|---|---|
| AC Coupling | Enabled | Enables frequency-shifting mechanism in the |
battery inverter.
AC PV Charge SOC| 90%| Recommended. Threshold for SOC-based
frequency shifting. Increased PV curtailment at high SOC helps regulate the
battery voltage and charge within the target range.
SOC Control| Enabled| Recommended. This requires external BMS or
Conext Battery Monitor.
Grid Code| The battery inverter grid code must be set according to local
utility interconnect requirements.| Ensure that grid code settings match the
PV inverter.
For advanced off-grid configuration refer to “Off- Grid Operation” on the next page.
For advanced grid code configuration or troubleshooting see “Troubleshooting” on page 1.
Table 2 PV inverter settings
| Setting | Value | Notes |
|---|---|---|
| Grid Code | The battery inverter grid code must be set according to local | |
| utility interconnect requirements. | Ensure that grid code settings match the |
PV inverter.
For advanced off-grid configuration refer to “Off-Grid Operation” below.
For advanced grid code configuration or troubleshooting see “Troubleshooting” on page 1.
Off-Grid Operation
For off-grid operation (with or without a generator), as a first option,
both the battery and PV inverters are recommended to be set to the same grid
code. For example for 60Hz, the recommended grid code is Rule 21 and for 50Hz
– Australia AS4777. The battery’s inverter frequency-shifting settings are
auto-configured to match the grid code and, consequently, the PV inverter’s
P(f) settings.
As a second option, when it is not possible to set the battery and PV inverter
to the same grid code, it is recommended to disable Freq-Watt P(f) Droop and
Freq-Watt P (f) PreDist on the battery inverter (Figure 6) in Grid Codes
settings. The smart AC-coupled PV inverter’s P(f) curve should be set to start
active power reduction at nominal frequency 50/60 Hz and finish it (fully
reduce to zero) at 54/64 Hz. This is what the battery inverter frequency shift
is configured to in case when grid code P(f) is not activated on it
.
Legacy PV inverters without frequency-watt function must be set so that they trip instantly once frequency is approaching 54/64 Hz.
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Document Number: 990-6421
Date: December 2020
Contact Information
For country-specific details, please contact your local Schneider Electric
Sales Representative or visit the Schneider Electric Solar Business website
at: https://solar.schneider-electric.com.
https://solar.schneider-electric.com
References
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