CSLB C-46 Solar ContractorPhotovoltaic System InstallationEasy
A solar technician is installing a new PV array on a residential rooftop. Before connecting the DC strings to the inverter, they perform a polarity check on each string. They measure a positive voltage reading from the positive lead to the negative lead. What does this measurement indicate?
- AThe string has a ground fault.
- BThe string has been correctly wired for polarity.
- CThe string has a short circuit.
- DThe string's bypass diodes are faulty.
Show answer & explanationAnswer & explanation
Correct answer: B. The string has been correctly wired for polarity.
A positive voltage reading when measuring from the positive lead to the negative lead confirms that the string is correctly wired with the intended polarity. This is a fundamental check to ensure proper operation and prevent damage to the inverter.
Why the other options are wrong
- A. A ground fault would typically result in a voltage reading to ground, not necessarily between leads.
- C. A short circuit would result in near zero voltage across the string.
- D. Faulty bypass diodes would affect output under shading, not necessarily reverse polarity.
PV String Polarity Check
Verifying the correct positive and negative terminals of a PV string using a multimeter before connection to prevent damage.
- Crucial before connecting to inverter or combiner box.
- Positive voltage from positive to negative is correct.
- Reversed polarity can damage inverters.
Memory trick: Positive to negative, a positive sign means it's fine!