CEI Renewable Energy System Inspection 2 — Questions and Answers
Question 1: When inspecting a grid-tied PV system, which device is required to disconnect the system from the utility grid during a power outage?
- Transfer switch
- Anti-islanding protection relay (Correct answer)
- Surge protective device
- DC disconnect switch
Correct answer: Anti-islanding protection relay
Anti-islanding protection is required by IEEE 1547 to prevent a PV inverter from energizing a de-energized utility line, protecting utility workers.
Question 2: NEC Article 690 requires PV source circuit conductors to be sized at what minimum percentage of the module's rated short-circuit current (Isc)?
- 100%
- 115%
- 125%
- 156% (Correct answer)
Correct answer: 156%
NEC 690.8(A) requires PV source circuit conductors to be sized at 125% of Isc, then multiplied by an additional 125% for continuous duty, yielding an effective 156% of Isc.
Question 3: A wind turbine installation requires a disconnect means that is capable of being locked in the open position. Where must this disconnect be located?
- At the utility meter
- At the wind turbine tower base
- Within sight of the turbine or lockable in the open position (Correct answer)
- Inside the main electrical panel
Correct answer: Within sight of the turbine or lockable in the open position
NEC Article 694 requires the wind turbine disconnecting means to be within sight of the turbine or capable of being locked in the open position to allow safe service.
Question 4: What is the primary purpose of a blocking diode in a PV string circuit?
- Increase output voltage
- Prevent reverse current flow from battery into the modules (Correct answer)
- Limit short-circuit current
- Protect against lightning surges
Correct answer: Prevent reverse current flow from battery into the modules
Blocking diodes prevent reverse current from flowing from the battery bank back through shaded or damaged PV modules, which could cause overheating.
Question 5: During inspection of a rooftop PV array, an inspector notes the modules are mounted directly on the roof with no air gap. What is the primary concern?
- Increased wind uplift risk
- Reduced module efficiency due to heat buildup
- Non-compliance with fire classification requirements (Correct answer)
- Inadequate grounding path
Correct answer: Non-compliance with fire classification requirements
Modules mounted flush to the roof without an air gap may not meet the fire classification requirements of NEC 690.12 and local building codes for fire spread resistance.
Question 6: For a battery energy storage system (BESS) connected to a PV system, NEC Article 706 requires the system to include which of the following?
- A dedicated transformer
- A listed battery management system (BMS) (Correct answer)
- An automatic transfer switch
- A ground fault circuit interrupter on every circuit
Correct answer: A listed battery management system (BMS)
NEC 706.15 requires energy storage systems to include a listed battery management system (BMS) to monitor and protect against overcharge, over-discharge, and thermal events.
Question 7: When inspecting a solar thermal system combined with an electrical system, what NEC article governs the electrical components of solar photovoltaic systems?
- Article 680
- Article 690 (Correct answer)
- Article 692
- Article 705
Correct answer: Article 690
NEC Article 690 specifically governs solar photovoltaic (PV) systems, including all electrical components from the modules to the point of interconnection.
CEI Renewable Energy System Inspection 2
When inspecting a grid-tied PV system, which device is required to disconnect the system from the utility grid during a power outage?