Example 1 – Selection & Sizing of solar DC Fuse
Problem:
Let’s consider a project with a two-string configuration. We have an array of 18 modules connected in series in a string.
Solution:
Step 1: Requirement of Overcurrent Protection Device
Requirement of overcurrent protection device (or a DC Fuse) is assessed by using below formula
[(Ns – 1) x Isc_mod] > [Imod_max_ocpr]
Putting values of parameters as provided in the problem :
[(Ns – 1) x Isc_mod] = [(2 – 1) x 12.28] = 12.28 A
Imod_max_ocpr = Max Series Fuse Rating = 20 A
Since, 12.28 A is less than 20 A, the above condition is not met.
Hence, there is no requirement of an Overcurrent device or a Solar DC Fuse in the system .