Inspection & Commissioning

Before you schedule the official inspection, walk through the entire installation yourself with the approved plan set in hand. The goal is to catch anything the inspector would flag — because fixing an issue before the inspection is quick and free, while fixing it after a failed inspection means rescheduling, waiting, and potentially paying for a re-inspection.

Here’s a systematic self-review checklist:

Roof and racking

• Panel count and layout match the approved roof plan
• Fire code setbacks and access pathways are maintained — measure them
• All racking hardware is torqued to spec (spot-check with a torque wrench)
• Bonding clips are installed at every rail splice and mount connection
• Flashings are properly installed under shingles (no exposed sealant-only penetrations)
• Wire management is neat — cables secured, no loose runs, no contact with roof surface

Electrical

• Conduit type, size, and routing match the plan set
• Conduit is properly supported with straps at code-required intervals
• Wire sizes match the single-line diagram for every circuit segment
• Disconnects and OCPD are installed in the correct locations with correct ratings
• Grounding path is continuous from panels through racking, conduit, inverter, and into the main panel’s grounding bus
• Solar breaker is installed in the correct panel position per the interconnection design
• Rapid shutdown equipment is installed and the initiation method works as designed

Labels

• Main panel label with PV system information and disconnect locations
• AC and DC disconnect labels with ratings
• Rapid shutdown initiator label per NEC 690.56(C)
• DC conduit warning labels (“WARNING: PHOTOVOLTAIC POWER SOURCE”) at required intervals
• All labels are durable, UV-resistant, correctly color-coded, and legible

Building inspectors verify that the installed system matches the approved plans and complies with the applicable codes. They’re not redesigning your system or second-guessing your component choices — they’re confirming that what’s on the roof and in the panel matches what was approved on paper.

A typical residential solar inspection covers:

Some inspectors will measure string voltage with a multimeter to verify the system is wired correctly and the voltage is consistent with the design. Have the approved plan set, equipment spec sheets, and any calculation sheets available on site for the inspector to reference.

Most inspection failures aren’t catastrophic design flaws — they’re avoidable oversights. After years of seeing inspection results across hundreds of projects, these are the issues that come up most often:

Every one of these is caught by a thorough pre-inspection self-review. The pattern is clear: the issues that fail inspections are almost always about attention to detail, not about fundamental design errors.

Once you’re confident the installation is ready, contact your building department to schedule the inspection. Some jurisdictions allow online scheduling; others require a phone call. Here’s what to expect:

• Lead time. Inspection scheduling varies from next-day in some jurisdictions to 1–2 weeks out in busy ones. Ask about lead times when you pull the permit so you can plan accordingly.
• Be present. You (or your electrician) should be on site during the inspection. The inspector may have questions, may want to see something demonstrated (like rapid shutdown), or may need access to locked areas. Being present also lets you hear feedback directly if corrections are needed.
• Have documents ready. Keep a copy of the approved plan set, equipment spec sheets, and any calculation sheets on site. Some inspectors reference these heavily; others barely glance at them. Have them available either way.
• Provide safe roof access. The inspector needs to see the rooftop installation. Have a ladder set up securely with the top extending above the roof edge. Some inspectors will go on the roof; others inspect from the ladder or from the ground with binoculars. Either way, the access should be ready.

If the system passes, you’ll receive a signed inspection card or certificate of approval. This document is required for your utility interconnection — keep it safe. If corrections are needed, the inspector will provide a written list. Address each item, then schedule a re-inspection.

Commissioning is the process of bringing the system online for the first time and verifying that everything works as designed. This happens after you pass inspection and receive permission to operate from your utility. Do not commission the system before PTO — your utility interconnection agreement governs when you can begin operating.

Modern inverters include built-in monitoring that tracks production data and system health. Setting up monitoring is one of the last steps in commissioning and is essential for verifying long-term performance.

• Connect to Wi-Fi or cellular. Most residential inverters connect to the internet via Wi-Fi. Some offer cellular connectivity as a backup or primary connection. Follow the manufacturer’s setup procedure to get the inverter online and reporting to their monitoring platform.
• Create your monitoring account. Register your system with the inverter manufacturer’s monitoring portal. This gives you a dashboard showing real-time production, daily/monthly/annual energy totals, and system alerts.
• Map panel positions (if MLPE). If you’re using microinverters or optimizers, the monitoring system can show production at each panel position. You’ll need to enter the serial number and physical position of each unit so the monitoring map matches your actual layout. This is invaluable for identifying underperforming panels.
• Set up alerts. Configure email or app notifications for system errors, communication loss, or production falling below expected levels. These alerts let you catch problems early before they become extended production losses.

Check your monitoring data regularly during the first few weeks. Compare daily production against weather conditions and your production estimate. If production is consistently lower than expected, it may indicate a wiring issue, a shading problem you didn’t account for, or an equipment malfunction — all easier to address sooner rather than later.

With the inspection passed, the last administrative step is obtaining permission to operate from your utility. This typically involves:

The time between passing inspection and receiving PTO ranges from a few days to several weeks depending on your utility. We covered interconnection timelines in detail in Chapter 9. If you submitted your interconnection application early in the process, this final step is often faster because the utility has already reviewed and approved your system — they’re just waiting for the completed installation confirmation.

When that PTO letter arrives and your inverter starts pushing power to the grid, take a moment to appreciate what you’ve accomplished. You managed a construction project on your own home. You navigated permitting, utility interconnection, equipment selection, and either did the physical work yourself or coordinated the tradespeople who did it for you. And you saved a significant amount of money in the process.

Your system is now generating clean electricity, reducing your utility bill, and adding value to your home. The panels on your roof will keep producing for 25–30 years with minimal maintenance — occasional monitoring checks, keeping the array reasonably clean, and being aware of new tree growth that might shade the array over time.

If something comes up down the road — a monitoring alert, an equipment question, a panel addition, or just a question about how the system is performing — we’re here. That’s what the hourly consulting service is for. You built this system with good engineering behind it, and we’re always available to help you maintain it.