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5 Planning the installation
Connecting the solar modules (DC)
5.7.1 Symmetrical and asymmetrical configura-
tion of the DC inputs
The inverter has a separate MPP tracker for each DC input (DC1
and DC2).
The two MPP trackers work independently, i.e. the optimum
working point is set separately for DC1 and DC2. This allows
the module strings connected to DC1 and DC2 to be differ-
ently aligned and differently dimensioned. A typical application
example is a building with a gable roof where the roof halves are
oriented to the east and west.
Variant 1: Symmetrical configuration of the DC inputs
The total input power is evenly divided (50%/50%) between DC1
and DC2.
Variant 2: Asymmetrical configuration of the DC inputs
The maximum permissible total input power can be distributed
between DC1 and DC2 in the range 67%/33% to 33%/67%
(M10A: Only 60%/40%). A distribution of 55%/45% or 45%/55%
is also possible, for example.
The percentages always relate to the instantaneous input power.
In an east-west roof-mounted system, this allows installing 67%
of the maximum input power on both roofs. This utilizes the effect
that the solar modules on both roofs provide maximum power at
different times of the day.
kW
East
7:00
Fig. 5.7:
Concept for a system with 2 MPP trackers and asym-
metric load distribution across the DC inputs
30
Total
East Roof
West Roof
West
13:00
Symmetrical design
Input Current
I max
U startup
Asymmetrical design
Input Current
I max
U startup
Fig. 5.8:
I-U characteristic curves for symmetric and asym-
metric configuration of the DC inputs (illustration of
principle)
19:00
Installation and Operation Manual for Power Inverter RPI M6A M8A M10A EU V4 EN 2020-07-13
Max. Power MPPT Range
Input Current DC 1
Input Current DC 2
Max. Power MPPT Range
Input Current DC 1
Input Current DC 2
See "13. Technical Data", Page 142 for cur-
rents and voltages.
U max
Input Voltage
U max
Input Voltage
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