Solar Installation Process Step by Step: Quote to PTO

The solar installation process step by step takes most homeowners anywhere from about one to four months, even though the panels often go on the roof in a day or two. Most of the time goes into design, permits, inspection and utility approval. Here’s what happens at each stage, from first quote to the day you’re allowed to switch the system on.

A widely viewed walkthrough of a residential solar install.

Electrical work can be dangerous: follow the manual, fuse and size every cable correctly, and use a licensed electrician for anything connected to household wiring.

The Solar Installation Process Step by Step

Step	What happens	Typical time
1. Quotes	Compare 3+ installers using your bills	1-3 weeks
2. Site survey	Roof, shading, panel and meter inspection	1 visit
3. Design	Layout, equipment, production estimate	1-2 weeks
4. Contract and financing	Sign, choose cash/loan/lease	Days
5. Permits	Building/electrical permit; HOA if needed	Days to weeks
6. Interconnection application	Utility reviews the system	Weeks
7. Installation	Racking, panels, inverter, wiring	1-3 days
8. Inspection	Local inspector checks code compliance	1 visit
9. Permission to operate (PTO)	Utility approves, may swap meter	Days to weeks

Timing varies widely by city and utility. These are typical ranges, not promises.

Steps 1-4: Quote, Survey, Design, Contract

Bring 12 months of electric bills. A good installer models production with tools like NREL’s PVWatts, explains roof condition, and lists every component by brand and model. Since the 25D federal credit ended for systems placed in service after Dec 31, 2025, check that any savings estimate doesn’t assume that credit.

Step 5: Permits

Your installer usually pulls the building and electrical permits. Many jurisdictions now use SolarAPP+, an NREL-developed tool that can approve standard residential systems instantly.

Step 6: Interconnection

Any grid-tied system needs the utility’s approval. You’ll sign an interconnection agreement that sets the rules for exporting power and the net metering or net billing tariff.

Step 7: Install Day

Crews mount racking, attach panels, run conduit, install the inverter or microinverters, any battery, and the disconnects. A main panel upgrade, if needed, may add a day.

Step 8: Inspection

The inspector checks NEC Article 690 and 705 items: labeling, rapid shutdown, grounding, conductor sizing and the point of interconnection.

Step 9: PTO

Don’t turn the system on until the utility grants PTO. Running early can violate your agreement.

What to Prepare Before Your First Quote

Having these ready speeds up every step:

12 months of electric bills or a usage download from your utility.
Your utility account number and meter number, needed for the interconnection application.
Roof age and material. If the roof needs replacing within the next several years, plan it first.
Main panel photos with the label showing the busbar and main breaker rating.
HOA rules, if you have an HOA.
Future loads, such as an EV or heat pump. See how many solar panels do I need.

Worked Example: A Typical Timeline

Here’s how a project might run in a city with online permitting and a utility with fast-track interconnection (illustrative):

Week	Milestone
1–2	Three quotes, site survey
3	Design approved, contract signed
4	Permit submitted (instant approval if the city uses SolarAPP+)
4–7	Utility interconnection review
8	Install, 1 to 2 days
9	City inspection passed
10–11	Utility grants PTO, meter swapped if needed

In a city with manual plan review, or with a utility backlog or a needed panel upgrade, the same project could take several months. Ask installers for their recent average time to PTO in your area.

What the Site Survey Checks

Item	Why it matters
Roof structure (rafter size and spacing)	Supports the added weight and wind loads
Roof condition and age	Avoids removal and reinstall costs later
Shading	Affects production and inverter choice
Main panel and service	Determines whether a panel upgrade is needed under NEC 705.12
Meter location and access	Required for utility work
Conduit routes	Affects cost and appearance

Reading the Design Package

Before you sign, the design should show:

System size in kW DC and inverter size in kW AC.
Panel layout on the roof, including fire setbacks.
Estimated first-year production in kWh, and the tool used (PVWatts or shade-adjusted software).
Equipment list with brands and model numbers.
Single-line electrical diagram and point of interconnection.
Price in total and $/W. Compare with LBNL’s 2024 medians in how much do solar panels cost.

What Happens on Install Day

A typical sequence for a roof-mounted system:

Crew arrives, sets up fall protection and staging.
Locates rafters and installs flashed attachments.
Mounts rails, then panels with microinverters or optimizers if used.
Runs conduit from the array to the inverter and main panel.
Installs the inverter, disconnects, monitoring and any battery.
Connects at the main panel. Power may be off for part of the day.
Labels all equipment, as the NEC requires.
Tests the system, then shuts it off until PTO.

After PTO: First Steps

Turn the system on following the installer’s instructions.
Set up monitoring and check that production matches the estimate over the first months.
Check your first solar bill for the right tariff. See reading kWh on your electric bill.
File warranty registrations for panels, inverters and batteries.
Keep paperwork together: contract, permit, inspection record, PTO letter and warranties. You’ll need them if you sell. See selling a house with solar.

For permits and utility steps in more detail, see solar permits and the interconnection agreement. For picking a company, see how to choose a solar installer.

FAQ

How long does solar installation take?

Install day is often 1-3 days; the whole process is commonly 1-4 months.

Who handles permits?

Usually the installer, but confirm it in the contract.

Can I turn on my panels before PTO?

Not for grid-tied systems. Wait for written approval.

How long after installation do I get PTO?

It depends on your utility. After the inspection passes, some utilities grant PTO within days and others take weeks.

Does my power go off during solar installation?

Usually only briefly, when the electrician connects the system at the main panel. A panel upgrade can mean a longer outage, coordinated with the utility.

What is SolarAPP+?

An automated permitting platform developed by NREL. Participating cities and counties use it to approve standard, code-compliant residential solar permits instantly online.

Do I need to be home on installation day?

Usually only at the start and end, and for any time power is shut off. Ask your installer, since the crew may need access to the main panel, garage or attic.

What if the inspection fails?

The installer fixes the listed items and schedules a reinspection. Common items include labels, conduit support and grounding details.

Sources: U.S. DOE, “Homeowner’s Guide to Going Solar” and “Homeowner’s Guide to Solar Financing”; NREL SolarAPP+; NFPA 70 (NEC) 2023 Articles 690 and 705; NREL, SolarAPP+; NFPA 70 (NEC) 705.12. Accessed Oct 2026.