How to Install Solar Panels: Step-by-Step Guide
From roof assessment to permission to operate — every stage of a solar installation, who does it, and how long it really takes.
The short answer
Installing solar panels is a seven-stage process: site assessment, design, permitting, mounting, panel placement, wiring and inverter, and inspection plus grid connection. The roof work takes just 1–3 days — but permits and utility approvals usually stretch the full timeline to several weeks or months. Here's every stage, in order.
Read this first: the safety disclaimer
This is an educational overview, not a DIY manual. A grid-connected solar installation combines high-voltage DC wiring, 240 V AC connections to your home's main panel, and structural work on a roof — and in most jurisdictions, the electrical code, permitting rules, and your utility's interconnection agreement require a licensed professional. A live residential string can carry several hundred volts of DC, which is far harder to interrupt safely than AC, and most manufacturers tie their 25-year panel and 10–12-year inverter warranties to professional installation. Small off-grid kits are the one reasonable DIY lane — grid-tied roof work belongs to licensed installers.
Step 1: Site and shade assessment
Every professional installation starts with the site, not the panels. The assessment answers four questions. Is the roof fit? A roof with less than about 10–15 years of remaining life usually gets replaced first, to avoid paying for array removal and reinstallation later. How much sun does it get? Orientation matters (true south in the Northern Hemisphere, true north in the Southern), but shade matters more: a single heavily shaded panel drags down the whole series string it sits in. Installers map shade across the day and the year, accounting for trees, chimneys, and neighboring buildings. Is the structure sound? The installer confirms the roof can carry the array's distributed load — light per square meter, but concentrated at the mounting anchors. How much energy do you use? Twelve months of utility bills (or a load survey for new builds) set the system size — most households in sunny climates land in the 5–10 kW range.
Step 2: System design and permitting
The design turns your usage into equipment and a layout: panel count from target annual kWh divided by expected per-panel yield (residential panels commonly run 400–450 W in 2026, so a 7 kW system means roughly 16–18 panels), an inverter sized to match (commonly ~80–100% of array DC capacity), and an electrical plan covering stringing, cable routes, and disconnect locations.
Then comes the paperwork — the slowest part of the whole process. Most jurisdictions require a building permit and an electrical permit with drawn plans and structural sign-off where required, plus a utility interconnection application before the system can be switched on. Reputable installers handle all of this as part of the project; if a quote asks you to pull your own permits, treat that as a red flag. (For a deeper look at what's on the other side of this paperwork, see our solar installation guide.)
Step 3: Mounting and racking
On pitched roofs, flashed mounts are the standard: standoffs anchored into the rafters (never just the sheathing), each sealed with metal flashing integrated into the shingle courses so water sheds over them. Finding the rafters accurately is the skilled part — missed rafters mean weak anchors and leak points. On flat or low-slope roofs, ballasted systems are common: the array sits in weighted trays with no roof penetrations at all, held down by gravity. Ground-mount systems use driven posts or concrete footings and tilted racks — pricier in materials and trenching, but they make cleaning, wiring access, and panel replacement far easier later.
Step 4: Panel placement and layout
With rails in place, panels are laid out, clamped, and torqued to spec. Placement follows three rules. Orientation and tilt: as close to ideal azimuth as the roof allows, tilted near the latitude angle — trimmed slightly in practice to balance summer and winter production and help rain wash dust off. Fire and access setbacks: many US jurisdictions enforce clearance paths along ridges and eaves (often around 3 feet) so firefighters can work around an array. Stringing: panels are grouped into series strings of similar orientation and shade exposure; mixing a shaded panel with unshaded ones wastes the unshaded panels' output, so good designs keep unlike panels on separate strings or use module-level optimizers.
Step 5: Wiring, inverter, and electrical
Within each string, panels connect in series, typically bringing a residential string to 200–400 V DC. String cables run in UV-rated conduit to a DC disconnect (the manual shutoff), then to the inverter. Wiring gauge is specified for the run length and current — 10 AWG copper is a common choice — and every connection uses weather-rated, lockable connectors torqued to spec, since a loose DC connection under load is a genuine fire risk.
Two architectures dominate: a central string inverter (cheaper, but one shaded string affects its peers) and microinverters — one small inverter per panel, with panel-level monitoring and shade resilience at higher equipment cost. Complex or partially shaded roofs favor microinverters or optimizers; clean simple roofs favor string inverters. See our string vs microinverter comparison for the full trade-offs.
From the inverter, AC wiring runs through an AC disconnect to a breaker in the main service panel. The installer verifies the panel has busbar capacity for the added breaker and that all grounding, bonding, conduit sealing, and warning labels meet code.
Step 6: Inspection, grid connection, and commissioning
Three gates stand between a finished install and a running system. First, the local inspection: structural mounts, grounding, labeling, disconnect placement, and code compliance are checked against the permitted plans. Second, the utility interconnection: the utility reviews the installation and often swaps your meter for a bidirectional net-metering meter. Third comes permission to operate (PTO) — the utility's written go-ahead, and only after it does the installer switch the system on.
Commissioning is the installer's final quality pass: each string's voltage and current are measured against design expectations, monitoring is configured, and the homeowner is walked through the monitoring app, the disconnect locations, and basic maintenance before handover.
Typical timeline, phase by phase
The roof work is the fastest part — budget your patience for everything around it. Durations vary widely by jurisdiction, so treat these as indicative ranges, and favor experienced local installers who know your permit office and utility queue: that familiarity is worth real weeks.
| Phase | What happens | Typical duration | Done by |
|---|---|---|---|
| Site assessment | Roof check, shade analysis, usage review | 1 visit | Installer |
| System design | Layout, stringing, electrical plan | 1–2 weeks | Installer |
| Permitting | Building + electrical permits, HOA | 2–8 weeks | Installer / authority |
| Utility interconnection | Application, net metering enrollment | 2–6 weeks | Installer / utility |
| Installation | Racking, panels, wiring, inverter | 1–3 days | Licensed crew |
| Inspection | Code compliance sign-off | days–2 weeks | Local inspector |
| Permission to operate | Meter swap, final approval | 1–4 weeks | Utility |
| Commissioning | Testing, monitoring setup, handover | 1 day | Installer |
Size your system before you call installers
Knowing your target system size before the first sales visit changes the dynamic — you can sanity-check every quote against your own math. Estimate your array size in the solar system calculator, then model cost and payback in the solar cost calculator.
Solar installation FAQ
Straight answers, no fluff.
Can I install solar panels myself?
Technically yes for small off-grid or ground-mounted kits in some jurisdictions, but a grid-connected rooftop system is not a DIY project in most places. Permits, utility interconnection agreements, and the electrical code generally require — and every manufacturer warranty assumes — licensed installers. Doing it yourself typically voids panel and inverter warranties and will fail inspection without permitted plans.
How long does solar panel installation take?
The physical install on a typical home takes 1-3 days of crew labor. The full process — design, permits, utility approval, install, inspection and permission to operate — usually spans several weeks to a few months, with permitting and the utility interconnection queue being the slowest steps, not the roof work.
Do I need a permit to install solar panels?
In most jurisdictions, yes — typically a building permit and an electrical permit, plus a utility interconnection agreement before you switch the system on. Many installers handle permitting as part of the project. Unpermitted systems risk fines, failed home-sale inspections, and utility disconnection.
Which way should solar panels face?
In the Northern Hemisphere, true south captures the most sun over the year; in the Southern Hemisphere, true north. Roof azimuth within about 30-45 degrees of ideal still produces strong output — panels facing slightly east or west lose only a modest amount — while heavy north-facing exposure (in the Northern Hemisphere) usually is not worth it.
Should solar panels go on the roof or the ground?
Rooftop is cheaper because the structure already exists, but ground mounts are easier to clean, orient perfectly and maintain, and leave the roof untouched. Ground mounts cost more for foundations and trenching, and need open land. If your roof is old or heavily shaded, ground mounting often wins on lifetime output.
What happens after the panels are installed?
Three gates: a local inspection verifying code compliance, the utility's interconnection approval (often including a meter swap for net metering), and formal permission to operate. Only then is the system switched on and commissioned — installers typically verify each string's output against the design before handing over.
Will my solar panels work during a power outage?
No — grid-tied systems shut down automatically during outages to protect line workers, as the electrical code requires. For backup power you need a battery with an islanding-capable inverter or a dedicated off-grid setup. See our guide to string inverters vs microinverters for how the equipment choices differ.
Run your own numbers
Reading is good. Math is better. Size your array from your electricity bills, then model the project cost and payback before your first installer visit.