String Sizing Info for Optimizers

2
Minimum and Maximum String Length
The minimum number of optimizers per string depends on the “Maximum Output Voltage” of the optimizer and on the “Nominal DC
Input Voltage” of the inverter: the optimizers connected in series in the string must be able to achieve the inverter’s nominal
voltage. There is a buffer added to ensure the operability of the string also in some shading or fault conditions.
The maximum number of optimizers per string was established to ensure proper communications between the optimizers and
inverter.
NOTE
When connecting multiple modules to commercial optimizers, in case of an odd number of modules per string it is allowed to connect
one optimizer with one module, as long the minimum number of modules per string is maintained as well.
General optimizers
Commercial optimizers
Single phase inverters
Minimum
8
N/A
Maximum
25
N/A
SE9KUS, SE14.4KUS
Minimum
10
8 optimizers, 16 modules
Maximum
25
30 optimizers
SE10KUS, SE20KUS, SE33.3KUS
Minimum
18
13 optimizers, 26 modules
Maximum
50
30 optimizers
Table 2: Minimum and maximum string length