
Sunny Boy 700
Technical Description
SB700-11:EE
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11
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SMA Regelsysteme GmbH
2.3 Technical design of the Sunny Boy 700
The Sunny Boy inverter is based on a power unit that operates with a very high effi-
ciency and optimal reliability. A MOSFET bridge converts the direct voltage coming
from the PV modules to a high frequency AC secondary circuit with 16 kHz. The volt-
age is then fed to the grid after being processed by a low-loss toroidal-core current
transformer.
Filter
Filter
Surge v
oltage protection
PV
-Str
ing
-
+
L
N
PE
Gr
id
R
ISO
V
PV
I
AC
f
AC
V
AC
MSD 1
MSD 2
Control circuit
supply
Current control
SRR
Operational control
BFR
Modem
(optional)
Pulse
Fig. 2.2: Block circuit diagram of the Sunny Boy 700
The PV input voltage range of the Sunny Boy 700 is designed for up to 10 standard
PV modules. It can be configured with three different voltage ranges so that even
small PV panel power can be optimally utilized (see chapter 3.3.2).
The current fed to the grid is perfectly sinus shaped and has a very low harmonic
distortion due to the fact that a one-chip computer manages the control. The sequen-
tial control system takes care of fully automatic operation and handles the MPP-
tracking (MPP = Maximum Power Point; fully automatic search for the PV output
voltage with highest output power). The sequential control system minimizes unnec-
essary losses in standby and in grid feeding mode.
The sequential control system also manages the communication with the corre-
sponding SMA data analysis tools Sunny Display, Sunny Data and Sunny Data Con-