Inverters In Off-Grid Systems

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Table Of Contents

SB-OffGrid-TI-US-en-14 | Version 1.4

Technical information

Table of Contents

Both in off-grid systems and in the event of grid failures in backup systems, grid fluctuations in the stand-alone

grid are possible. This may cause severe deviations in nominal voltage and nominal frequency. Despite such

fluctuations, all the components of the system must function without problems.

This technical information will inform you about the following topics:

• Which PV inverters you can use in off-grid systems and backup systems.

• Which parameters you need to set in the PV inverter.

• What type of communication you need to install in backup systems.

• Which values the parameters of PV inverters will display in off-grid operation.

• How the output power of the PV inverter can be limited by the Frequency-Shift Power Control function

(FSPC) of the off-grid inverter.

PV Inverters

Use of PV inverters in off-grid systems and backup systems in North and South America

Summary of content (10 pages)

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Technical information PV Inverters Use of PV inverters in off-grid systems and backup systems in North and South America Table of Contents Both in off-grid systems and in the event of grid failures in backup systems, grid fluctuations in the stand-alone grid are possible. This may cause severe deviations in nominal voltage and nominal frequency. Despite such fluctuations, all the components of the system must function without problems.
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1 Choosing the PV Inverter SMA America, LLC 1 Choosing the PV Inverter You can use the following PV inverters in off-grid systems or backup systems: PV inverter Off-grid system Backup system Sunny Boy 700-U ✓ ✖ Sunny Boy 1800-U ✓ ✖ Sunny Boy 2100-U ✓ ✖ Sunny Boy 2500-U ✓ ✖ Sunny Boy 3300-U ✓ ✖ Sunny Boy 3800-U ✓ ✖ Sunny Boy 6000-U ✓ ✖ Sunny Boy 3000-US ✓ ✓ Sunny Boy 4000-US ✓ ✓ Sunny Boy 5000-US ✓ ✓ Sunny Boy 6000-US ✓ ✓ Sunny Boy 7000-US ✓ ✓ Sunny Boy 8000-US ✓ ✓
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SMA America, LLC 1 Choosing the PV Inverter System failures due to excessive power output of AC sources in the stand-alone grid If the power of the AC sources (e.g., PV inverters) in off-grid systems or backup systems is too high, it may cause system failures. • Design the total nominal AC power of the PV inverters to be no more than twice as high as the nominal AC power of the off-grid inverters.
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2 Configuration of the PV Inverters SMA America, LLC 2 Configuration of the PV Inverters 2.1 Configuration Options WARNING Danger to life due to electric shock If the power distribution grid fails, there is a risk of backfeed in PV inverters which are configured for off-grid operation. • Find out about the standards and guidelines applicable to off-grid systems and backup systems at your location. • Only operate PV inverters configured for off-grid operation in off-grid systems or backup systems.
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SMA America, LLC PV inverter 2 Configuration of the PV Inverters Sunny Boy Control Sunny WebBox Computer with Sunny Data / Sunny Data Control software Sunny Boy 4000TL-US ✓ ✓ ✓* Sunny Boy 5000TL-US ✓ ✓ ✓* Sunny Boy 6000TL-US ✓ ✓ ✓* Sunny Boy 7000TL-US ✓ ✓ ✓* Sunny Boy 8000TL-US ✓ ✓ ✓* Sunny Boy 9000TL-US ✓ ✓ ✓* Sunny Boy 10000TL-US ✓ ✓ ✓* Sunny Boy 11000TL-US ✓ ✓ ✓* * You will also need a service cable for data transmission (USB Service Interface, SMA order number: USBP
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2 Configuration of the PV Inverters SMA America, LLC 2.2 Parameter Setting for Off-grid Operation The parameters "Default"/"CntrySet" and "BackupMode"/"Op.BckOpMod" are used to set the PV inverters to off-grid operation. With the "Default"/"CntrySet" parameter, you can set the country data set. With the "BackupMode"/"Op.BckOpMod" parameter you can set whether the PV inverter is to form a backup system with the off-grid inverter via RS485.
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SMA America, LLC 2 Configuration of the PV Inverters 2.3 Parameter Settings for Back-up Operation In a backup system, the off-grid inverter is connected to the power distribution grid and communicates with the PV inverters via RS485. Therefore, you must equip the off-grid inverter and each of the PV inverters with an RS485 Piggy-Back. In a cluster, only the master of the off-grid inverter must be equipped with an RS485 Piggy-Back. The parameters "Default"/"CntrySet" and "BackupMode"/"Op.
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2 Configuration of the PV Inverters SMA America, LLC Backup systems with SI 4548-US-10, SI 5048U and SI 6048-US-10 In the event of a power distribution grid failure, the off-grid inverter sets the "Default"/"CntrySet" parameter of the PV inverter to "OFF_Grid". Thus, if a grid failure occurs, the off-grid inverter is able to regulate the PV inverters via Frequency Shift Power Control (FSPC).
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SMA America, LLC 3 Values of the Parameters in Off-grid Operation 3 Values of the Parameters in Off-grid Operation The setting of the "Default" parameter to "OFF_Grid" automatically sets the PV inverter parameters to the values listed in the following table: Parameters Test current Vac.Min Vac.Max Fac-delta‒ Lower range in which the Sunny Boy is active relative to f0 Fac-max+ Upper range in which the Sunny Boy is active relative to f0 dFac-Max Max.
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4 Frequency-Shift Power Control (FSPC) SMA America, LLC 4 Frequency-Shift Power Control (FSPC) If PV inverters are connected on the AC side in off-grid operation or back-up operation, the Sunny Island must be able to limit their output power. This situation can occur when, for example, the Sunny Island's batteries are fully charged and the PV power available from the PV array exceeds the power required by the connected loads.