Sunny Boy 1800U
Installation and Operator’s Manual
SB2500U-11:NE
-
49
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SMA Regelsysteme GmbH
7.1.1 Minimum MPP-voltage of the PV panel
Often a fixed lower MPP voltage limit of the inverter is not useful when the cells of the PV
panel have very high temperatures. This means the MPP voltage of the PV panel de-
creases and the inverter cannot feed the maximum power from the PV panel to the low-
voltage grid. The inverter remains at the lower limit of input voltage and cannot follow the
MPP of the PV panel. Therefore the Sunny Boy has a flexible MPP voltage range.
There is a fixed ratio between the minimum MPP voltage V
MPP
min the Sunny Boy loads
onto the PV panel and the grid voltage V
AC
as shown in
Fig. 7.1
.
Depending on the current grid voltage the minimum DC voltage is assessed and fixed.
This flexible MPP voltage range lets the user make optimum use of the specific device
characteristics while the energy yield is increased.
120
130
140
150
160
170
100
105
110
115
120
125
130
V
AC
[V]
V
Mp
p
m
in
[V
]
138 V DC
171 V DC
105 V AC
132 V AC
120 V AC
156 V DC
Fig. 7.1:
Minimal MPP-voltage as a function of grid voltage
