Enphase recommends keeping Vrise under what percentage from the point of supply to the AC isolator?

• A. 5%
• B. 1%
• C. 10%
• D. 2%

Answer: (D)

The key idea being tested is how much the voltage on the customer side can rise when PV power backfeeds into the system. Keeping Vrise under two percent from the point of supply to the AC isolator limits the potential voltage increase that can occur with high solar output and low load. This small cap helps ensure the voltage seen at the AC isolator stays within typical service tolerances, protects connected equipment from overvoltage, and keeps protection and safety devices operating correctly. It also accounts for variations in supply voltage and line impedance so the installation remains reliable under different conditions.