Published June 7, 2026 · Updated June 7, 2026 · 7 min read
The short answer
Going solar in California involves a local building permit from your city or county (the AHJ), an inspection, then utility interconnection and final Permission to Operate (PTO). The install itself is quick; the permit, inspection, and utility steps are controlled by agencies and can take weeks. A good installer manages the whole process for you.
By Vinnie Curcie, Founder & CEO
The big picture: who has to say yes
Before your solar system can legally turn on, two outside parties have to approve it: your local Authority Having Jurisdiction (AHJ) — the city or county building department that issues the permit and inspects the work — and your utility, which authorizes the system to connect to the grid and grants final Permission to Operate (PTO). The physical installation is usually the fastest part. The waiting comes from these agency- and utility-controlled steps.
Step 1: design and the building permit (AHJ)
First we design the system and submit a permit application to your AHJ, including engineering and electrical plans. Some California jurisdictions use SolarAPP+ for near-instant automated permitting; others review plans manually, which takes longer. This step is controlled by the building department, so timelines vary by city — from same-day in automated jurisdictions to a few weeks where review is manual. We prepare the package to that jurisdiction's requirements to avoid avoidable rejections.
Step 2: installation and inspection
Once the permit is issued, the physical install is typically completed in a day or two for a standard residential system — longer if it's paired with re-roofing or a panel upgrade. After install, the AHJ sends an inspector to verify the work meets code. Inspection scheduling is on the building department's calendar, so the wait depends on local backlog. If the inspector flags anything, we correct it and re-inspect.
Step 3: utility interconnection and PTO
After passing inspection, the project goes to your utility for interconnection approval and Permission to Operate (PTO). This is where you're formally placed on NEM 3.0 (for SCE, SDG&E, or PG&E) and cleared to switch the system on. PTO is entirely on the utility's timeline and is often the longest single wait in the whole process — frequently several weeks. Your system stays off until PTO is granted; turning it on before then isn't permitted.
Realistic timelines (and why honesty matters)
End to end, a straightforward residential project commonly runs several weeks to a few months from contract to PTO. The spread is wide because so much of it is outside any installer's direct control — AHJ permit review, inspector scheduling, and utility PTO all move on their own calendars. Any company promising a guaranteed fast turnaround is overpromising on steps it doesn't control. We give you honest expectations and keep you updated at each handoff.
How OC Solar manages the process
We handle the paperwork end to end — permit submittal, scheduling inspections, and the utility interconnection and PTO applications — so you're not chasing your city or utility yourself. Knowing local permit offices and utility processes is exactly where an established, local installer earns its keep: it gets you to PTO with fewer rejections and delays. We've operated in Southern and Central California since 2016 under CSLB #1023627.
FAQ
A straightforward residential project commonly runs several weeks to a few months from contract to Permission to Operate. The install itself is quick — the time is in the permit review, inspection scheduling, and utility PTO, which are controlled by the AHJ and utility, not the installer.
Incentives and rates change. This page is kept current — but always confirm specifics for your home.
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