Advantages of Fronius
inverters with optional DC
overvoltage protection
Information class: Public, Fronius International, 06.04.2023
(SPD)
© Fronius International GmbH
Version 01 04/2023
Business Unit Solar Energy
Advantages of Fronius inverters with optional DC overvoltage protection (SPD) 2/9
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Advantages of Fronius inverters with optional DC overvoltage protection (SPD) 3/9
An SPD (Surge Protective Device) is a device for protection against transient voltages and pulse
currents. Surges can be caused by lightning – direct strike or indirect strike into the electrical systems
– or by switching operations in the public grid.
According to international and national standards, PV systems must be protected against overvoltages
using SPDs (e.g., IEC 61643-32, IEC 60364-7-712)
Figure 1: Example of an installation requirement for SPD in a PV System (source: IEC 61643-32)
(1) as close as possible to the DC connection of the inverter
(2) as close as possible to the AC connection of the inverter
(3) in the main distribution board
(4) As close as possible to the PV generator field (or immediately upon entering the structural
system)
(s) Separation distance between external lightning protection system (LPS) and PV generator field
Advantages of Fronius inverters with optional DC overvoltage protection (SPD) 4/9
Exceptions for shorter cable/line lengths (“10 m rule”)
Figure 2: Exceptions for shorter cable/line lengths (’10 m rule”)
Advantages of Fronius inverters with optional DC overvoltage protection (SPD) 5/9
With Fronius inverters, there is no need for SPDs in the PV generator array (4) regardless of the
"10 m rule"!
This applies under the following conditions:
− The Fronius SPD option is used (not all SPDs available on the market meet the requirements!)
and
− No external lightning protection system is available or there is an external lightning protection
system installed and the separation distance 's' is maintained.
and
− Only new PV modules for a system voltage of at least 1000 V are used (existing systems or
older PV modules would have to be checked individually to ensure whether all applicable
standards are met)
and
− All lines from the PV generator to the inverter (e.g. several +/- string lines) including the
equipotential bonding conductor are laid together (in parallel) by the substructure (= reduction
of all loop areas!).
Figure 3: Avoidance of loops surfaces with equipotential bonding (source: IEC 61643-32 and Fronius)
Advantages of Fronius inverters with optional DC overvoltage protection (SPD) 6/9
Attention!
The exception to the "10m rule" does NOT apply if an external lightning protection system
exists or is planned to be installed and the separation distance 's' is/will be NOT maintained ('s'
between all installations and the lightning protection system!) (In this case, partial lightning
currents are to be expected in the PV system).
There are also other installation variants where not all SPDs (1, 2, 3, 4) are required.
Regional or country-specific rules and regulations may deviate from this.
Fronius can grant this exception under the conditions described because the SPDs used by Fronius in
connection with its own inverters meet certain exception conditions of the standards and guidelines
mentioned.
(Justification: The voltage protection level (Up) of the integrated SPDs at the DC connection of the
inverters, is with a maximum of 4000 V and is not greater than 0.5 times the rated surge voltage (Uw)
of the connected PV generator arrays).
The majority of inverter-integrated SPDs on the market do not automatically meet the requirements of
installation and application standards (e.g. IEC 60364-7-712, IEC 61643-32), but they only meet inverter
standards (IEC 62109, etc.).
The integrated Fronius SPD solutions are also very well designed for the installation and application
standards and cover a large part of the use cases. Thanks to the adjustable, integrated remote
signaling, the system operator receives an automatic message via the Fronius Solar.web online portal
if the surge protection device is damaged.
Advantages of Fronius inverters with optional DC overvoltage protection (SPD) 7/9
Fronius SPD solutions
Fronius inverter Overvoltage protection Item number Preassembled/
Retrofit Kit
Primo 3.0 – 8.2
Symo 3.0 – 8.2
Symo 10.0 – 20.0
Eco
Primo GEN24 Plus
Symo GEN24 Plus
4,240,335,CK
DC SPD 8.2 Type 1+2 M
Option DC SPD Typ 2 - S 4,251,019
Option DC SPD Typ 2 - M 4,251,020
Preassembled
Option DC SPD Typ 1+2 - S 4,251,024
Option DC SPD Typ 1+2 - M 4,251,025
Retrofit DC SPD Typ 2* 41,0001,0709
Retrofit DC SPD Typ 1+2* 41,0001,0719
Option DC SPD Typ 2 - S 4,251,019
Option DC SPD Typ 1+2 - S 4,251,024
Option DC SPD Typ 1+2 - M 4,251,025
DC SPD Type 1+2 GEN24 4,240,313,CK Retrofit Kit
SPD Type 1+2 4,240,334
Preassembled
Retrofit Kit
Retrofit Kit
Tauro
SPD Type 2 4,240,332
Tauro ECO SPD Type 1+2 ECO 4,240,333
SPD Type 2 ECO 4,240,331
*For multistring applications, 2 pieces of SPD must be ordered. Does not include cabling. Cabling can
be ordered under article number 43,0004,5448 and covers both SPD types.
4,240,334,CK
4,240,332,CK
4,240,333,CK
4,240,331,CK
Available as
Preassembled and
Retrofit Kit (CK)
Advantages of Fronius inverters with optional DC overvoltage protection (SPD) 8/9
Figure 4: Built-in SPD Fronius Symo 10-20 kW
Figure 5: Built-in SPD Fronius Symo GEN24 Plus
Advantages of Fronius inverters with optional DC overvoltage protection (SPD) 9/9
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