5 Planning installation
Installation and Operation Manual for Inverter RPI M50A_12s V1 EU EN 2017-03-09
32
5.7.1 Symmetric and asymmetric configuration
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 differently
aligned and differently dimensioned. A typical application exam-
ple is a building with a gable roof where the roof halves are ori-
ented to the east and west.
Variant 1: Symmetrical design of the DC inputs
The total input power is evenly divided (50%/50%) between DC1
and DC2.
Variant 2: Asymmetrical design of the DC inputs
The maximum permissible total input power is divided between
DC 1 and DC 2 within a range of 60%/40% to 40%/60%. A distri-
bution of 55%/45% or 45%/55% is also possible, for example.
The percentages relate to the instantaneous input power. With
an east-west roof-mounted system, this allows installing 60% 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.
7:00
13:00
19:00
kW
Total
East Roof
West Roof
East
West
Fig. 5.8:
Concept for a system with 2 MPP trackers and asym-
metric configuration of the DC inputs
Symmetrical design
Imax
Umax
Ustartup
Input Current
Input Voltage
Max. Power MPPT Range
Input Current DC 1
Input Current DC 2
Asymmetrical design
Imax
Umax
Ustartup
Input Current
Input Voltage
Max. Power MPPT Range
Input Current DC 1
Input Current DC 2
Fig. 5.9:
I-U characteristic curves for symmetric and asym-
metric configuration of the DC inputs (illustration of
principle)
See “13. Technical data”, page 164 for currents
and voltages.
