Most homeowners expect solar installation to take a few days. The physical roof work does — but the full process from signed contract to the day your system goes live typically takes 2–6 months. The delays aren't the installer's fault (usually): permits, utility interconnection queues, and inspection scheduling are the real bottlenecks. Knowing what to expect at each step helps you stay in control of your project timeline.
Disclaimer: Timelines vary significantly by location. Urban areas with high solar adoption (California, New Jersey, New York) often have the longest permit queues. Some jurisdictions have streamlined to online permits with 24-hour turnaround; others still require manual review taking 4–12 weeks.
Key Takeaways
- The physical roof installation takes 1–3 days for a typical 9 kW system; the full permit-to-PTO timeline takes 2–6 months
- Permitting and utility interconnection are the longest steps — combined, they typically account for 6–16 weeks of the total timeline
- Most installers handle all permitting and utility paperwork for you — but tracking progress yourself prevents delays from slipping unnoticed
- Permission to Operate (PTO) from your utility is the final milestone — don't turn your system on without it or you risk losing grid access
Overview: The 7 Steps of Residential Solar Installation
Before getting into each step, here's the complete timeline at a glance:
| Step | What Happens | Typical Duration | Who Does It |
|---|---|---|---|
| 1. Site Assessment | Roof evaluation, shading analysis, electrical review | 1–3 days | Installer |
| 2. System Design | Panel layout, equipment selection, production estimate | 3–10 days | Installer |
| 3. Permitting | Building permit application with local authority | 1–12 weeks | Installer |
| 4. Equipment Ordering | Panels, inverter, racking, wiring ordered | 1–4 weeks | Installer |
| 5. Roof Installation | Physical panel mounting and wiring | 1–3 days | Install crew |
| 6. Inspection | City/county inspector verifies code compliance | 1–3 weeks (scheduling) | Local inspector + installer |
| 7. Interconnection / PTO | Utility reviews, installs net meter, issues PTO | 2–8 weeks | Utility + installer |
Step 1: Site Assessment
Your installer visits the property — either in person or via satellite tools like Google Sunroof — to evaluate your roof. They're looking at four things: structural condition (can it support panel weight?), shading (trees, chimneys, neighboring buildings), roof orientation and pitch (south-facing, 10–35° pitch is optimal), and electrical infrastructure (panel capacity, meter location, interconnection options).
If your roof needs repair before installation — cracked tiles, worn asphalt shingles, soft decking — installers won't install on it. Roof repairs are your cost and responsibility, not theirs. A structural inspection before signing your solar contract can save you a mid-project surprise.
The electrical review checks whether your main service panel has capacity for the solar system. Many older homes (100A service, crowded panel) need a panel upgrade — typically $1,500–$4,000 — before solar installation can proceed. Ask about this explicitly during the site assessment.
Step 2: System Design and Proposal
After the site assessment, your installer produces a design: panel layout on your specific roof, equipment specifications (panel brand/model, inverter type), shading analysis with expected annual production in kWh, and a 25-year financial model showing estimated savings.
This is the right time to ask questions. What panel brand are they proposing? What's the warranted degradation rate? Is the production estimate based on NREL PVWatts data? Do you have the option to upgrade to microinverters for better shading performance?
Our Best Solar Panels for Home guide covers what to look for in panel specifications. Our Solar Sizing Guide explains how production estimates are calculated so you can verify the numbers independently.
Step 3: Permitting
Building permits for solar are required in virtually every U.S. jurisdiction. Your installer handles the permit application — pulling structural drawings, electrical diagrams, and equipment spec sheets into a permit package. This step is where timelines diverge most sharply by location.
According to the Solar Energy Industries Association's 2024 data, permit processing time ranges from same-day (states with adopted streamlined solar permitting) to 12+ weeks in jurisdictions with manual review processes. California cities are among the slowest; some Arizona and Texas cities with online permitting systems process applications within days.
A few states have enacted "SolarAPP+" or similar digital permit programs. If your jurisdiction uses one of these, the permit step drops to days rather than weeks. Ask your installer which system your city uses.
Step 4: Equipment Ordering
Once the permit is in process, your installer orders equipment. Lead times in 2026 vary: domestic panel manufacturers (Silfab, Qcells' Georgia facility) typically ship within 1–2 weeks. Imported panels and some inverter models run 2–4 weeks. Supply chains have stabilized since 2022–2023, but tariff changes can create sporadic shortages.
If your installer doesn't place the equipment order until the permit is approved, add those lead times to your timeline — they're sequential, not parallel. Good installers order equipment concurrent with permit processing.
Step 5: Roof Installation
The physical installation is the shortest and most visible step. A crew of 2–4 technicians mounts the racking, installs the panels, runs conduit and wiring, connects the inverter, and ties the system into your electrical panel. For a typical 9 kW system (22–25 panels), this takes 1–2 days on a straightforward roof.
Expect noise and activity on your roof for the installation days. The crew will need access to your electrical panel — clear the area. You don't need to be home, but being available by phone helps if questions arise.
What gets installed: mounting hardware bolted through roof decking into rafters (sealed with flashing), panel frames attached to mounting rails, panels clicked into frames, DC wiring run to combiner box or microinverters, conduit from roof to inverter to main panel.
Step 6: Local Inspection
After installation, your local building authority sends an inspector to verify code compliance — primarily the electrical work (proper conduit, grounding, disconnect switches) and structural attachment. In most jurisdictions, your installer schedules this and needs to be present.
Inspection scheduling depends on your local inspector's availability. In busy markets, waits of 1–3 weeks are common. If the inspector finds issues, there's a re-inspection cycle — add another week or two.
Passing inspection clears the way for the final step.
Step 7: Utility Interconnection and PTO
The final hurdle is your utility company. They need to review the system design, approve the interconnection, install or reprogram your net meter (often a smart meter swap), and issue Permission to Operate (PTO).
Utility interconnection queues vary wildly. Some utilities (especially smaller municipal utilities or co-ops) turn around PTO in 1–2 weeks. Large investor-owned utilities in high-solar markets — Pacific Gas & Electric, ConEdison — can take 6–8 weeks. Your installer tracks this process, but check in if you haven't heard anything after 3 weeks.
Critical: Do not turn on your solar system before receiving written PTO from your utility. Operating without interconnection approval can result in the utility denying your net metering application and requiring the system to be taken offline. The wait is frustrating — it's also required.
Common Reasons Projects Get Delayed
- Permit queue — Most common delay; nothing you or the installer can do except wait
- Equipment backorder — Specific panel models or inverters on 4–6 week lead times
- Roof repair required — Discovered during assessment; adds weeks for repair + re-inspection
- Panel upgrade needed — Electrical panel too small; adds $1,500–$4,000 and 2–4 weeks
- Utility backlog — PTO queue at the utility; especially bad in high-solar markets
- Inspection fail — Minor code issue requiring fix and re-inspection
Track your project milestone dates. A good installer gives you a shared project tracker or at minimum regular status emails. If you hit week 4 with no permit update, ask.
Bottom Line
The solar installation process is mostly waiting — permitting, utility queues, inspection scheduling. The physical work is fast. The best thing you can do is sign your contract in the right season (spring or fall for faster scheduling), confirm your installer orders equipment concurrently with permitting, and track your milestones actively so delays don't compound.
Once your system is running, the ongoing commitment is minimal. See our Solar Panel Maintenance Guide for what ownership looks like after PTO. Before you sign with any installer, use our Solar ROI Calculator to verify their payback projection, and our Solar Lease vs Buy Calculator if you're comparing financing options.
Related Guides
- Home Solar Panels: The Complete 2026 Guide — Full overview of costs, financing, brands, and ownership from start to finish.
- How Many Solar Panels Do I Need? — Size your system before your installer does — so you can verify their proposal.
- Best Solar Panels for Home in 2026 — Which panel brands to request from your installer and what specs to verify.
- Solar Panel Maintenance Guide: Cleaning, Lifespan & Warranty (2026) — What owning a solar system looks like after your system goes live.
