Wrenches,
I am curious if anyone can offer guidance on how to treat the *multiple*
Isc ratings for bifacial modules when calculating the maximum circuit
current for PV source/output circuits. As a reminder, the maximum circuit
current is defined as "the sum of the short-circuit current ratings of the
PV modules connected in parallel multiplied by 125 percent." (NEC 2020)
However, bifacial module datasheets generally include *two* short-circuit
current ratings - one at STC and another at BSTC ("Bifaciality given for
rear side irradiation on top of front side STC"). As an example, a certain
bifacial module has an Isc @ STC rating of 10.6 A and an Isc @ BSTC rating
of 11.6 A. What are designers using for the 690.8(A) calculation? Still
sticking with the STC rating? or instead using the BSTC rating? or perhaps
a hybrid of both (depending on some qualitative assessment of the site
conditions and expected back side gain)?
--
Corey Shalanski
Jah Light Solar
Portland, Jamaica
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