CSLB C-46 Solar ContractorPhotovoltaic System InstallationMedium
A solar installation team is performing a system startup on a new 10 kW residential PV array using microinverters. After connecting all AC and DC wiring, what is the CRITICAL first step to energize the system safely and correctly?
- AOpen the inverter's internal AC disconnect.
- BClose the main utility service disconnect.
- CClose the AC breaker for the PV system in the main service panel.
- DClose the PV array DC disconnects.
Show answer & explanationAnswer & explanation
Correct answer: C. Close the AC breaker for the PV system in the main service panel.
For microinverter systems, which are AC-coupled at the module level, the correct and safe startup procedure involves energizing the AC side first. This allows the microinverters to sense the grid and perform their anti-islanding functions before they start producing power. Closing the AC breaker for the PV system in the main service panel provides the necessary grid reference.
Why the other options are wrong
- A. Inverters typically have internal AC disconnects that are kept closed during normal operation; 'opening' it would prevent the system from energizing.
- B. The main utility disconnect should remain closed (or be closed if it was opened) to provide grid power, but it's not the 'first' step specific to the PV system after all wiring.
- D. Microinverters are typically plug-and-play on the DC side, and DC power is applied when modules are exposed to light. The 'energizing' step is about connecting to the grid, which is AC-side.
Microinverter System Startup
The sequence of steps to safely and correctly bring an AC-coupled microinverter PV system online after installation.
- Prioritize AC connection to establish grid reference.
- Each microinverter operates independently.
- No central DC disconnect is typically required due to rapid shutdown compliance.
Memory trick: AC first, then DC, then monitor the flow!