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Monday, November 6, 2023

Question:

Good morning CQD. I was wondering why, for calculating max current for a photovoltaic (PV) system, 690.8(A)(1)(2) calls for a 3-hour average? Is there a rationale for the 3 as opposed to 2 or 4 hours? Thanks, Chris Ramirez
A

Answer:

Hello Chris, when using the method listed in Section 690.9(A)(1)(a)(2) to calculate PV maximum circuit current, the 3-hour average accounts for real-world conditions, while still maintaining a somewhat conservative approach. Situations that can impact PV circuit current like cloud-edge-effect can cause a sudden increase in irradiance due to reflection of passing clouds. These conditions are unlikely to last for periods of more than 3-hours.

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