Solar & Photovoltaic Systems Inspection

Per IBC Section 1607.13.5, rooftop PV systems must be designed for applicable dead loads, live loads, wind loads, and snow loads. Per IRC R324.4, PV mounting systems must be flashed and waterproofed to prevent roof leaks. All roof penetrations must maintain the fire classification of the roof assembly per IBC Section 1509.7. Mounting hardware must be attached to structural members, not sheathing alone, and must comply with manufacturer installation instructions.

1. Verify mounting attachments are secured into roof rafters or structural members per engineered plans

2. Inspect all roof penetration flashings for proper installation and waterproof sealing

3. Confirm the racking system is installed level and per manufacturer torque specifications

4. Verify the structural engineering report accounts for wind uplift, dead load, and applicable snow loads

5. Check that fire setback pathways comply with IBC Section 1505.11 or IRC R324.6 for firefighter access

- Mounting bolts attached to sheathing only without reaching structural rafters

- Inadequate flashing or sealant at roof penetrations causing leaks

- Racking not installed level or bolts not torqued to specification

- Fire access pathways not maintained per code requirements

Per NEC 690.12, modules must be listed and labeled per UL 1703 and installed per manufacturer instructions. Module wiring must be secured and protected from physical damage per NEC 690.31. Modules must be grounded or use listed equipment grounding methods per NEC 690.43. Module spacing must allow for thermal expansion and provide adequate ventilation beneath the array.

1. Verify all modules are UL 1703 listed and labels are visible and legible

2. Confirm modules are securely clamped to the racking per manufacturer mid-clamp and end-clamp specifications

3. Check module wiring is neatly routed, secured with listed cable management, and protected from abrasion

4. Verify proper grounding using equipment grounding conductors or listed grounding clips

5. Confirm module spacing allows for thermal expansion per manufacturer requirements

- Modules not properly secured with mid-clamps and end-clamps per specifications

- Wiring left loose or draped across the roof surface subject to damage

- Missing or improper equipment grounding connections between modules and racking

- Modules installed without adequate spacing for thermal expansion

Per NEC 690.8, DC circuit conductors must be sized for 125% of the maximum circuit current. Per NEC 690.31(A), DC wiring must be installed in raceways, listed PV wire, or USE-2 cable. All DC connectors must be listed, compatible, and of the same manufacturer per NEC 690.33. Combiner boxes must be listed, properly rated, and include overcurrent protection per NEC 690.9. Per NEC 690.12, rapid shutdown must reduce conductor voltage to 80V within 30 seconds.

1. Verify DC conductors are properly sized for 125% of maximum circuit current

2. Confirm all DC connectors are listed, mated from the same manufacturer, and fully engaged

3. Check combiner box fuses or breakers are properly sized for string overcurrent protection

4. Verify rapid shutdown system is installed and functional per NEC 690.12

5. Inspect DC conduit and wiring for proper support, protection, and labeling per NEC 690.31

- DC conductors undersized for the actual circuit current

- Mismatched DC connector brands creating unreliable connections

- Rapid shutdown system not installed or not functioning per NEC 690.12

- DC wiring not properly labeled with voltage and current warnings

Per NEC 690.8, inverters must be listed per UL 1741 and installed per manufacturer instructions. Inverter input voltage and current ratings must be compatible with the PV array output. Per NEC 705.12, the inverter AC output connection must comply with utility interconnection requirements. Inverters must be installed in accessible locations with adequate ventilation and working clearance per NEC 110.26.

1. Verify the inverter is UL 1741 listed and the nameplate data matches the system design

2. Confirm inverter DC input voltage does not exceed the inverter maximum input voltage rating

3. Check that the inverter is mounted per manufacturer specifications with required clearances for ventilation

4. Verify working clearance of 30 inches wide by 36 inches deep by 78 inches high per NEC 110.26

5. Confirm the inverter is configured for the correct utility grid voltage and frequency settings

- PV array open-circuit voltage exceeds inverter maximum input voltage on cold days

- Inverter installed without adequate ventilation causing thermal derating

- Insufficient working clearance for maintenance access

- Inverter grid settings not configured for local utility requirements

Per NEC 705.12(B)(2), the sum of the inverter output breaker and the main breaker must not exceed 120% of the busbar rating (the 120% rule). The AC disconnect must be accessible to the utility and clearly labeled per NEC 690.13. Per NEC 705.12, supply-side connections require overcurrent protection and must comply with utility interconnection agreements. All AC conductors must be properly sized per NEC 310.

1. Calculate and verify the 120% busbar rule is satisfied at the point of interconnection

2. Confirm the AC disconnect is accessible, clearly labeled, and visible from the inverter

3. Verify AC conductor sizing matches the inverter output current rating with proper derating

4. Check that the backfed breaker is at the opposite end of the bus from the main breaker and labeled "DO NOT RELOCATE"

5. Confirm the utility interconnection agreement is approved and the production meter is installed if required

- 120% busbar rule violated, creating an overloaded bus condition

- AC disconnect not labeled or not accessible to the utility

- Backfed breaker not positioned at the opposite end of the bus from the main breaker

- Missing "DO NOT RELOCATE" label on the backfed breaker

Per NEC 690.41, PV systems must have a grounding electrode system compliant with NEC Article 250. Per NEC 690.43, all exposed non-current-carrying metal parts must be grounded. Equipment grounding conductors must be sized per NEC 690.45 and Table 250.122. For systems with ground-fault protection per NEC 690.5, the ground-fault detection device must be tested and verified functional.

1. Verify the grounding electrode conductor is properly connected to the grounding electrode system

2. Check equipment grounding conductors for proper sizing per NEC 690.45 and Table 250.122

3. Confirm all racking, modules, junction boxes, and inverters are bonded to the equipment grounding system

4. Test ground-fault protection device for proper operation per manufacturer instructions

5. Verify grounding and bonding connections are accessible, tight, and protected from corrosion

- Equipment grounding conductors undersized for the circuit

- Grounding connections corroded or loose at the grounding electrode

- Module frames not bonded to the racking grounding system

- Ground-fault protection device not tested or not functional

Per NEC 690.7, open-circuit voltage must be verified and must not exceed the inverter maximum input voltage at the lowest expected ambient temperature. Per UL 1741, the inverter must perform anti-islanding protection testing. The system must be inspected by the AHJ before interconnection to the utility grid. All labels and markings required by NEC 690.56 must be in place, including the main service disconnect PV system label.

1. Measure open-circuit voltage of each string and compare to design specifications

2. Measure short-circuit current of each string to verify module connections

3. Verify all required labels are installed: main service disconnect, AC disconnect, DC disconnect, and conduit labels

4. Confirm the AHJ inspection is passed and the utility permission to operate is received

5. Test system production against expected output using irradiance readings and verify monitoring is operational

- String voltages not matching design specifications indicating miswired modules

- Required NEC 690.56 labels missing at the main service disconnect

- System energized before AHJ inspection and utility permission to operate

- Monitoring system not configured or not reporting accurately