How long does it take to install solar panels

Updated: Nov 11, 2024
11 min

Most people asking how long does it take to install solar panels expect to hear a day or two — and they're not wrong about the physical installation. Panels go up in 1 to 3 days. But getting from contract to a live, grid-connected system takes 1 to 3 months.

The gap comes from permitting, inspections, and utility approval — steps that happen mostly in the background. Here's what to expect at each stage.

How long does the full process actually take?

SolarAPP+

a free automated permitting tool developed by the National Renewable Energy Laboratory that lets building departments review solar applications instantly

For a typical grid-tied residential system, the full timeline from signing to switching on looks like this:

Stage	Time
Site survey & system design	1–2 weeks
Permits & approvals	2–6 weeks
Physical installation	1–3 days
Inspection	1–2 weeks
Utility interconnection (PTO)	2–6 weeks
Total	45–90 days

PG&E & SCE

Pacific Gas and Electric and Southern California Edison, the two largest utility providers in California

The physical installation takes a fraction of that time. Most of the calendar goes to paperwork, queues, and approvals — not labor.

Timelines vary by location. In jurisdictions that use SolarAPP+, automated permit review can cut approval time from several weeks down to 1–5 business days. On the other end, major utilities like PG&E and SCE average 4 to 8 weeks just for interconnection approval. Where you live plays as big a role in the timeline as the size of your system.

Solar panel installation timeline: step by step

Step 1 — Site survey and system design: 1–2 weeks

An engineer visits your home to build the foundation for the entire project. They assess roof angle, condition, and available space; check for shading from trees or neighboring buildings; inspect your electrical panel; and review your historical electricity usage. All of this goes into a permit-ready system design. Some installers now do preliminary assessments remotely using satellite imagery, which can speed things up before the in-person visit.

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What you're doing at this stage

Scheduling the visit and pulling together your recent utility bills.

Step 2 — Permits and approvals: 2–6 weeks

Your installer submits the system design to the local building department, which reviews it against electrical and building codes. Most applications are approved within a few weeks — but if the submission doesn't meet local requirements, it gets sent back for revision, which adds time and cost. County jurisdictions tend to move slower than city ones.

In areas using SolarAPP+, automated review can cut approval down to 1–5 business days. Ask your installer upfront whether your jurisdiction uses it.

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What you're doing at this stage

Waiting. Your installer handles the paperwork.

Step 3 — Physical installation: 1–3 days

The crew arrives, mounts the racking system, installs the panels, runs conduit and wiring, and connects the inverter. A standard residential system built on 400-watt panels is usually done in a single day. Larger or more complex roofs may take two to three days. Everything happens outside — your daily routine stays intact.

What you're doing at this stage: going about your day. No need to be home.

Step 4 — Inspection: 1–2 weeks

A municipal inspector visits to verify the installation matches the approved permit plans and meets safety codes. This is separate from the utility process — it's your local building department signing off before the system can be activated. Scheduling depends on inspector availability in your area.

What you're doing at this stage: waiting for the appointment, then being available to provide access.

Step 5 — Utility interconnection and Permission to Operate (PTO): 2–12 weeks

The final — and often longest — wait. Your utility reviews the interconnection application and issues a Permission to Operate, confirming the system is safe to connect to the grid. Until PTO arrives, the system is fully installed but cannot be turned on.

Timeline varies widely by utility: large providers like PG&E and SCE average 4 to 8 weeks, while smaller municipal utilities often process applications in 2 to 3 weeks. Residential systems generally receive PTO within 2 to 12 weeks after installation — the range is wide because utility queue lengths change seasonally.

There's nothing you or your installer can do to speed up the utility's internal process.

What can delay your solar installation?

Even with a good installer, the answer to how long does it take to install solar panels? depends heavily on factors outside anyone's direct control.

Permitting alone accounts for 25–40% of the total project timeline — before any other variables come into play.

Permit backlog. Not every building department moves at the same pace. County jurisdictions tend to be slower, and some are simply understaffed. Standard review takes 2–4 weeks; complex projects can stretch to 8.

HOA approval. If you live in a community with a homeowners association, you'll likely need architectural committee sign-off before work begins. Review timelines range from a few days to several weeks depending on how often the HOA board meets.

Roof or electrical panel condition. If your roof needs repairs, that work has to happen first. Similarly, older homes sometimes require a main panel upgrade before the solar system can be connected — a separate permit and inspection that adds 1–3 weeks.

Equipment lead times. Panels are rarely the bottleneck, but batteries and certain inverters can carry 4–6 week lead times during high-demand periods.

Utility interconnection queue. As of early 2024, Berkeley Lab tracked over 11,600 residential projects waiting for grid connection. In busy regions, this queue alone can push your PTO out by weeks beyond the standard estimate.

Installer availability. Demand peaks in spring and summer. Popular installers in busy markets book out weeks ahead — the sooner you sign, the better your position.

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How to speed up your solar installation

You can't control how fast your utility processes paperwork — but you can avoid adding delays on your end.

Start earlier than feels necessary
Installer queues fill up fast in spring and summer. Signing a contract in winter often means a smoother, faster spring installation.
Ask about SolarAPP+ upfront
If your jurisdiction uses it, permit approval drops from weeks to days. One question to your installer before you sign can save you several weeks later.
Check your roof and electrical panel early
If either needs work, get it assessed before installation is scheduled — not after. Coordinating both projects together prevents costly panel removal and reinstallation down the line.
Research your utility's PTO timeline
Ask your installer how long interconnection approval typically takes with your specific utility. It sets realistic expectations and helps you plan around the wait.
Sort out HOA approval early If you live in an HOA community, submit the application as soon as the system design is ready — don't wait until permits are approved.

Does installation time differ by system type?

System size and grid connection status change the timeline significantly. Here's a quick comparison before we break each down:

System type	Typical timeline	Permits required	Utility approval
Grid-tied residential	45–90 days	Yes	Yes
Off-grid residential	2–6 weeks	Varies by location	No
Commercial (15 kW+)	3 months – 2+ years	Yes	Yes
RV / boat / cabin	1–2 days	Usually no	No

Grid-tied residential

The standard scenario covered throughout this article. All five steps apply — survey, permits, installation, inspection, and utility interconnection. Most homeowners go live within 45–90 days of signing a contract. A typical setup uses anywhere from 10 to 20 500-watt solar panels, depending on roof size and energy usage.

Off-grid systems

Off-grid installations skip utility interconnection entirely, removing the longest and least controllable step from the process. Permitting requirements vary by location and are often simpler than grid-tied projects. In areas with straightforward local rules, a well-prepared off-grid system can be operational within 2 to 6 weeks of signing. The exact timeline depends on how much of the work you're doing yourself versus hiring out.

Commercial solar

How long does it take to install commercial solar panels? For systems starting at 15–20 kW, the realistic minimum is 3 to 6 months. Larger projects layer in environmental reviews, utility interconnection studies, and multi-agency permitting — each with its own queue. Supply chain issues with transformers and switchgear can add further delays that are difficult to predict at the outset.

Vasilii Smirnov

Solar Installation Expert

Commercial systems are a completely different story. Depending on the scale, these can take months or even years to complete. The hardest part is getting the papers and scheduling the inspections. Supply issues may also significantly delay completion.

RV, boat, and cabin systems

Small off-grid setups — typically one to two budget solar panels paired with a charge controller and a battery — don't require permits in most cases and can be installed in a day or two. Timeline here depends on your comfort level with basic electrical work rather than any external approval process.

So...

For most homeowners, the realistic timeline from signing a contract to turning on a live solar system is 1 to 3 months. The physical installation takes 1 to 3 days — the rest of the calendar goes to permits, inspections, and utility approval.

If you're planning around a specific date — a home sale, a construction project, or the end of a state incentive — work backwards from that deadline and add a buffer. Signing a contract in fall typically means a smoother winter or early spring activation. Signing in spring means competing with peak-season demand.

The one step worth asking about before you commit to an installer: how long does utility interconnection typically take in your area? That single number will tell you more about your real timeline than anything else.

FAQ

Does adding a battery affect the installation timeline?

In most cases, yes. Battery storage requires additional permitting and a separate inspection in many jurisdictions. Depending on your location and the battery model, it can add 1–3 weeks to the overall timeline. If storage is part of your plan, factor it in from the start rather than adding it later — retrofitting a battery after the fact involves a separate permit and installation visit.

Can I install solar panels myself to save time?

For a grid-tied system, DIY installation isn't a realistic shortcut. Most utilities require a licensed electrician to sign off on the interconnection application, and many jurisdictions won't issue permits to homeowners acting as their own contractor. For off-grid setups — a cabin, RV, or boat — self-installation is common and straightforward.

Do I need to be home during installation?

Not necessarily. The crew works outside and doesn't need access to the interior of your home in most cases. You'll need to be available — or have someone available — for the site survey, the municipal inspection, and the final utility meter exchange.

How soon after PTO can I start seeing savings on my bill?

Your system begins generating power the day PTO arrives and you switch it on. How quickly that translates to bill savings depends on your utility's net metering policy, your rate structure, and how much of your usage falls during daylight hours.

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Andrey Gorichenski

Senior Editor

Andrey had been a news editor and freelance writer for a number of medias before joining A1 SolarStore team. Climate change and its impact on people's lives has always been among his interests and it partially explains his degree in Philosophy and Ethics.