When using a production CT, what PV branch circuit conductors are used to measure PV generation?

• A. L2
• B. L1
• C. L1 and L2
• D. Neutral

Answer: (B)

PV production current is the current the PV system injects into the panel, so the production current transformer should be placed on the conductor that carries that PV current. In a typical 120/240 V single‑phase service, the PV system ties into one hot leg, and the current from PV flows through that leg to the panel. Clamping the CT around that hot leg captures the PV-generated current directly, giving an accurate measure of PV output. The neutral isn’t the path for PV generation, so it isn’t used for this measurement, and the other hot leg would only be correct if the PV were connected to that leg. In short, measure the leg through which PV current flows (the hot conductor used for PV, usually L1).