Studer Solsafe concept Application Note
Application Note 003
Anti-blackout system for grid connected solar
installations (Solsafe concept)
General description
The Solsafe concept is a system which will
automatically switch from a grid feeding
inverter connected to the public grid to a
backup grid powered by an invertercharger.
The installation of the Solsafe concept in a
grid connected solar system enables to
secure totally or partially the power supply
in case of a power cut and allows the use of
solar power when the grid is off.
Features & advantages
Backup system for grid connected solar
installation.
Grid feeding with solar inverter.
Hassle free cabling, quick installation
and easy commissioning with the
Solsafe S-Box.
Application Schematic
Minimal configuration
Range of inverters
o Compact Series :
o All XPC serie
o All C serie
o All HPC serie
o Xtender Series :
o All XTH serie
o All XTM serie
Xtender
o Software vers. : 1.3.28 and higher
RCC02 / 03 (Only for Xtender series)
o Software vers. : 1.3.32 and higher
o RCC User level : Expert
AN003-V.3.0.6-10 | © STUDER INNOTEC SA
Figure 1, Solsafe concept with the Solsafe S-Box
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Detailed description
The Solsafe concept
The Solsafe concept is a backup system for grid
connected solar installations.
This solution enables to secure totally or
partially the power supply in case of a power
cut, and to keep on using the solar energy being
produced.
Note that all inverter-chargers of Studer Innotec
are bi-directional. This allows integrating any of
them into the Solsafe concept.
The Solsafe system can be fully wired by the
Application Note 003
installer. In that case, Studer is only supplying
the inverter-charger (Xtender or Compact
series) and the ARM-01 Module (for Compact
series only).
The wiring schematics for the Solsafe system
and Solsafe three phase system are at disposal
in the appendices (available at the end of this
document).
Solsafe S-Box
For the Solsafe system a cabling
solution exists, the S-Box.
The S-Box offers :
Hassle free cabling
Quick installation
Easy commissioning
Figure 3, Solsafe concept
Compared to other similar solutions, the Solsafe
concept offers the following advantages :
It allows a great flexibility by choosing
independently the grid-feeding power
(matching the solar generator) and the
stand-alone power (matching the peak
consumption of the user).
The grid-feeding inverter can be chosen with
high voltage input range (lowering wiring
costs).
The wiring can be optimized by placing the
grid-feeding inverter near the solar field
It allows a possible upgrade of existing grid-
connected installations.
The inverter-charger allows a fast charge
from the grid (important in case of frequent
power cuts hindering a complete charge of
the battery).
The power available in case of islanding is
added (inverter-charger Pnom + grid-feeding
instantaneous power).
Its allows an upgrade of existing stand-alone
installations that are connected to the grid
afterwards (adding value to the investment)
It standardizes the amount of products to
maintain and makes the staff training easier
(this concept can be implemented with all our
combis, XTH, XTM, XPC, Compact and
HPC).
It allows to work with standard grid-feeding
inverters (SolarMax, Fronius, …).
The S-Box can be supplied in 4
versions :
S-Box 25A for Compact Series (S-Box-25C)
S-Box 25A for Xtender Series (S-Box-25X)
S-Box 25A with ENS Module for Compact
Series (S-Box-25C-E)
S-Box 25A with ENS Module for Xtender
Series (S-Box-25X-E)
Figure 2, S-Box
It ensures that no grid-feeding from the
battery is possible.
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Solsafe concept situations
The Solsafe concept can be described by these four different situationsi
The grid is present
K1 / AUX1 is in “bypass
mode”.
K2 / AUX2 is switched on
the grid (feeding grid).
The grid charges the
batteries.
No grid and batteries
fully charged
K1 / AUX1 is in “power cut
mode”: the backup inverter
supplies the consumers
from the batteries.
K2 / AUX2 is switched on
the grid. Solar energy is not
necessary as long as the
battery is “full”.
Application Note 003
No grid and batteries
partly charged
K1 / AUX1 is in “power cut
mode”: the consumers are
supplied by the backup
inverter (batteries) and / or
solar energy.
K2 / AUX2 is switched on
the backup grid. Solar
energy is used for
supplying the consumers
and/or the batteries.(Bidirectional output of
inverters)
No grid and batteries
discharged
K1 / AUX1 is in “bypass
mode” and disconnects
completely the consumers.
It will switch back in “power
cut mode” when the battery
will recover a partial
charged level.
K2 / AUX2 is switched on
the backup grid. Solar
energy is used for charging
the battery.
i
K1, 2 are for Compact series and AUX1, 2 are for Xtender Series
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Application Note 003
Solsafe system behavior example
The graph below shows in detail the behavior of the Solsafe system in every possible case
Grid
Secured loads
Battery
volt age
Secured loads
power
Solar power
OK OK
K1/
AUX1
K2/
AUX2
K11
K14-K15
K12
K13
Gene ral d escriptions
Grid present and battery in floating phase. The solar production is sold to the grid.
No grid, no solar production (night time). Secured loads supplied by the inverter-charger.
No grid but solar production. Secured loads are supplied by the solar production and if necessary
by the invert er-charger.
No grid but solar production. Secured loads are supplied by the solar production. The excess of
the solar production is used to charge the battery.
No grid and battery voltage too low (battery fully discharged).
Loads will stay disconnected until battery has recovered 25% capacity.
Grid present. The charge of the battery is done from the grid.
The solar production is sold to the grid.
Relays descriptions
K1 / AUX 1 is always actuated until warning for LVD (low voltage disconnection), and actuated again when
battery level is 50%.
K2 / AUX 2 is actuated when the unit is in inverter mode (no AC in) with a battery voltage which is less t han
the absorption voltage and the temperature less than 65°C.
K14 is closed when the grid is present or when K11 is open.
K15 force K14 when the grid is present.
K12 and K13 are mechanically and electrically interlocked.
K11 and K14 are mechanically and electrically interlocked.
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Solsafe concept, installation
design and commissioning
General information for Solsafe concept
with Compact series
This particular application requires a Compact
(XPC, C or HPC) driving the external auxiliary
relay module ARM-01
The ARM-01 is a module consisting of 4
auxiliary relays to use only with the Compact
series. The K1 and K2 relays have a dedicated
function to the Solsafe application. The K3 relay
is not used and the K4 relay is a replication of
the auxiliary contact of the inverter-charger and
can be programmed for particular applications
This module is already included in the S-Box
(type S-Box-25C).
Using the S-Box (type S-Box-25C) will greatly
facilitate the wiring of Solsafe system.
General information for Solsafe concept
with Xtender series
This particular application requires an Xtender
(XTH or XTM) with auxiliary contact AUX1 and
AUX2 specifically programmed to drive the
contactor of the source switch-over.
inverter is not similar to the one of the grid)
Application Note 003
ii
.
Thus, if the function “jumps impedance” is
mandatory, it is required to add an external ENS
module in the grid feeding path.
Studer Innotec recommends two ENS modules
of the company UfE GmbH. The ENS 26 for
single phase system and the ENS 31 for three
phase system.
The module ENS 26 is already included in the
S-Box type S-Box-25C-E and S-Box-25X-E.
System dimensioning
Grid Inverter
The power of the grid inverter can be freely
chosen but the maximum output power should
not be higher than the inverter-charger nominal
power.
Note that the wiring should be in accordance
with the manufacturer’s and local’s
prescriptions.
Battery
Battery should be sized according to the backup
time requirement, but we recommend a
minimum size of : C10 ≥ 5x P
Inverter-charger (Compact series or Xtender
series)
pv/Ubatt
.
The specific programming is done by loading
the preset Solsafe available in the libraries of
predefined parameters (see the programming
guide on the next page for more information).
Using the S-Box (type S-Box-25X) will greatly
facilitate the wiring of Solsafe system.
General information for the Solsafe
concept with Xtender three-phase
system
This particular application requires 3 Xtender
(XTH or XTM) with auxiliary contact AUX1 and
AUX2 specifically programmed to drive the
contactor of the source switch-over.
Note that Studer Innotec does not supply prewired S-Box for three-phase systems. But it is
possible to order all the necessary equipment at
Studer Innotec (List of equipment, preset
Solsafe and information on the assembly are
available in appendices).
ENS module
When using the Solsafe concept, the function
“impedance jumps” (or ENS
must be always turned off (impedance of
i
) on the grid inverter
The inverter-charger must be sized according to
the maximum secured power.
For the Compact and Xtender series,
the stand-by must be at 0 to work with
the Solsafe system.
Notes
i
An ENS-Module is used to connect decentralized
electricity generators to the public electricity supply and
in the event of faults in the mains supply, the ENSModule interrupts the feeding of electricity of the
monitored phase into the mains to prevent an islanding
effect.
The following deviations are monitored :
overvoltage and undervoltage
frequency deviation
impedance jumps
These instructions are directly extracted from Chapter
2.1 of Module ENS manual of the company UfE GmbH.
More information available on www.ufegmbh.de
ii
Grid inverter manufacturer will give the procedure to
deactivate the function “impedance jumps”.
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RCC -02 / -03 programming guidei
Go to Expert level
User level {5012}
Your level is
i
The code is availabl e in the
user manual RCC -02 / -03
Load preset “Solsafe”
ii
Application Note 003
Press SET and search with :
Press SET and insert the code :
426468
Press SET :
EXPERT
Press SET and searc h with :
Save and restore
files {5013}
Press SET and search with :
Advanced backup
functions
{5069}
Press SET and search with :
Save and restore
Xtender files
{5050}
Press SET and search with :
Load Xtender
parameters preset
{5045}
Press SET and choose
the preset '' Solsafe''
with and press SET to validate:
Wait until the pr eset
is installed
Notes
i
(Only for Solsafe concept with Xtender series and Solsafe concept with Xtender three phase system).
ii
Preset “Solsafe” description available in the appendices.
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