SM1230-XAX Datasheet, PDF (1/10 Pages) National Semiconductor (TI) – Power Optimizers Partial Deployment for Single String Systems

Power Optimizers Partial
Deployment for Single
String Systems
National Semiconductor
Application Note 2120
Hiroyuki Takahashi
March 7, 2011
Introduction
The SolarMagic power optimizers allow for greater flexibility
when designing a photovoltaic array compared to the tradi-
tional series connected panels in a string with parallel con-
nected strings to form an array. The default configuration for
a SolarMagic assisted string is to have all of the panels con-
nected to a SolarMagic DC/DC power optimizer (Figure 2).
Assisted strings with SolarMagic are optimized for mismatch-
es between panels and between strings, maximizing the sys-
tem efficiency by re-capturing the energy that would have
been lost caused by the mismatch.
If you build a system which has a Central Inverter (hereinafter
called “C/I”) with its own Maximum Power Point Tracking
(“MPPT”) control connected with a single string which has a
SolarMagic unit on each panel in the string, it’s possible that
the power may not be sufficiently harvested under certain sit-
uations which would cause a voltage mismatch between
strings. This is caused by the interaction between the MPPT
of the C/I and the MPPT of SolarMagic. To address this, there
is a configuration, as shown in Figure 3, which is a design of
a single string applying SolarMagic power optimizer units par-
tially, not on every panel, within the string. This configuration
eliminates interference between MPPT controls and maxi-
mizes the array power output.
SolarMagic Power Optimizers
There are two series of SolarMagic power optimizers, the first
generation SM1230 series and the second generation
SM3320 series as shown in Figure 1 with the appropriate
electrical specifications. Both power optimizer series of prod-
ucts can utilize partial string implementation as long as the
string design is based on the SolarMagic power optimizer in-
put and output specifications.
30134901
FIGURE 1. Variation of the SolarMagic Power Optimizers
SolarMagic™ is a trademark of National Semiconductor Corporation.
© 2011 National Semiconductor Corporation 301349
30134902
FIGURE 2. Example of Basic Configuration
6 Panels x 4 Strings (with 2 assisted strings)
30134903
FIGURE 3. Example of Single-String Configuration
6 Panels (with 3 assisted panels)
Input Specifications
SM1230-xAx SM1230-xBx
V_MPP max
40V
80V
I_MPP max
8.5A
5.5A
V_OC max
50V
100V
I_SC range 9.2A to 10.4A 5.9A to 6.4A
SM3320-xAx
xBx
xSx
xFx
40V
42V
50V
70V
11A
9A
9A
9A
50V
80V
80V
100V
11A
9A
9A
9A
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