beanland
Senior Member
- Location
- Vancouver, WA
2011 NEC 690.8(1) refers to "module rated short circuit currents". The short circuit current from a module is a function of the light shining on it. There are two standard "ratings" the STC and NOCT. STC uses 1000w/sqm light and NOCT uses 800W/sqm. The difference in Isc is similar to the level of light, NOCT is ~80% of STC. STC is considered a somewhat hypothetical maxiumum under unrealistic ideal conditions. NOCT is considered a real-world maximum.
Which rating is required by NEC? Where does it say?
The problem is that if I test a module at 1500W/sqm, the short circuit current will be 50% higher than STC. That could be a valid rating, too.
Since I must assume that the module can produce 125% of its "rating" and then must size conductors to 125% of that, selecting the NOCT rating can make a BIG different.
Which rating is required by NEC? Where does it say?
The problem is that if I test a module at 1500W/sqm, the short circuit current will be 50% higher than STC. That could be a valid rating, too.
Since I must assume that the module can produce 125% of its "rating" and then must size conductors to 125% of that, selecting the NOCT rating can make a BIG different.