How long does a solar site assessment usually take?

A site assessment typically runs 45 to 90 minutes, depending on the complexity of your property.

Will the assessor give me a final quote during the visit?

No, the assessor is there to confirm usable space, structural condition, shading, and electrical capacity. A finalized design and binding quote come later.

What should I have ready before the assessor arrives?

Gather your utility bills, clear roof access, note any shading issues, and have electrical panel details on hand. Preparing these items in advance helps the visit produce a useful quote.

How to Prepare Your Home for a Solar Site Assessment: A Beginner's Checklist

By the end of this guide, you’ll know exactly what to gather, clear, and check before a solar site assessor arrives — and you’ll understand what each item is for, so the visit produces a useful quote rather than a vague estimate. A site assessment typically runs 45 to 90 minutes, and the quality of that visit depends heavily on what you’ve prepared in advance. Most of the work happens before the assessor rings the doorbell.

How to Prepare Your Home for a Solar Site Assessment: A Beginner’s Checklist

What a Site Assessment Is (and Isn’t)

An assessor — sometimes a sales rep with technical training, sometimes a dedicated site surveyor — visits to confirm four things: usable roof or ground space, structural condition, shading exposure, and electrical capacity. They are not there to finalize your design or hand you a binding quote on the spot. That comes later, after the data is processed.

Understanding this shapes your preparation. The assessor needs access, information, and honest answers. Missing any one of those pushes the real quote back by weeks.

Step 1: Collect 12 Months of Electricity Bills

This is the single most important item, and it takes the longest to assemble. Pull together a full year of utility statements — most utility portals let you download 12 to 24 months of usage history as a single PDF. If you’ve only lived in the home for part of that period, gather whatever exists plus any records from the previous owner if available.

Why the full year? System sizing depends on seasonal swings. A homeowner who uses 900 kWh in April and 2,100 kWh in August needs a very different system than the annual total alone suggests. Assessors look for the peak summer and winter months to judge whether battery storage or net metering makes more sense for your usage pattern.

Checklist:

Log into your utility account and download 12 months of statements
Note whether usage is measured in kWh or billed in dollars only
Record your current rate plan (flat, time-of-use, tiered)
Note any planned changes — an EV purchase, a heat pump install, a home addition

That last item matters more than many homeowners expect. Adding an EV typically increases household consumption by 3,000 to 5,000 kWh per year, which can shift a recommended system size by 20% or more.

Step 2: Walk Your Roof and Note Its Condition

Before the assessor arrives, do your own visual sweep — from the ground with binoculars is fine, and safer. You’re looking for three things: the roof’s approximate age, its material, and any visible damage.

Roof age is the make-or-break detail. Solar panels commonly carry 25-year performance warranties, and most installers won’t mount on a roof with less than 5 to 10 years of remaining life. If your asphalt shingles are 18 years into a typical 20-to-25-year lifespan, a reputable installer will often recommend reroofing first — and it’s far cheaper to do that before panels are bolted down than after.

Roof Type	Typical Lifespan	Mounting Notes
Asphalt shingle	20–25 years	Standard rail mounts; common and inexpensive
Standing seam metal	40–70 years	Clamp mounts avoid roof penetrations; often preferred
Tile (clay/concrete)	40–50 years	Requires tile hooks; higher labor cost, more breakage risk
Wood shake	20–30 years	Fire code may restrict; some jurisdictions discourage solar
Flat/rolled membrane	15–25 years	Ballasted or adhered mounts; drainage must be verified

Also note the pitch and orientation. A roof facing roughly south (in the northern hemisphere) with a pitch between 15° and 40° is generally the easiest case. East- and west-facing roofs still work but produce somewhat less and more spread-out output across the day.

Checklist:

Estimate roof age from purchase records or inspection reports
Identify the material and note any cracked, lifted, or missing pieces
Photograph any existing damage for your own records
Note the general direction the main roof planes face
Check gutters and downspouts for clogs or detachment

Step 3: Map the Shade Around Your Property

Shading is where self-assessment helps most. The assessor will bring a shade-measuring tool — often a handheld device that photographs the sky and estimates solar access — but your own observations add context that a single visit can’t capture.

Walk the yard at three times: roughly 9 a.m., noon, and 3 p.m. Note which trees cast shadows on the roof and at what times. Deciduous trees lose leaves in winter, so their summer shade may not be as limiting as it first appears. Evergreens are the opposite — their shade persists year-round and matters more.

A rough rule of thumb: a tree casting shade on more than about 20% of a roof plane during peak sun hours (roughly 9 a.m. to 3 p.m.) will measurably reduce production. Shade on 50% or more often pushes the economics toward not installing at all, or toward a smaller system on an unshaded section.

If X, then Y:

If shade comes only from deciduous trees, note this — the assessor may still recommend full roof coverage.
If shade comes from a large evergreen or a neighboring building, ask about microinverters or power optimizers, which reduce losses from partial shade.
If shade covers most of the roof, ask about ground-mounted or carport options instead.

Checklist:

Note tree species and canopy size within 30 feet of the roof
Record shade patterns at 9 a.m., noon, and 3 p.m.
Ask about any local tree ordinances before planning removals
Check for future shading risks — a neighbor’s fast-growing tree, new construction planned nearby

Step 4: Locate and Photograph Your Electrical Panel

The main electrical service panel is the second most important item after your bills. The assessor needs to see its amperage rating, its age, and how full it is with breakers.

Most modern homes have a 200-amp panel, which generally accommodates a residential solar system without upgrades. Homes with 100-amp service may require a panel upgrade, which commonly costs $1,500 to $3,000 depending on region and code requirements. That’s a real number worth knowing before the visit.

Open the panel door — carefully, and only if you’re comfortable doing so — and photograph the inside with the breaker labels visible. If you’re not comfortable, just photograph the outside and note any labels you can read. Do not remove the dead front cover; that’s for a licensed electrician.

Checklist:

Photograph the panel exterior with the amperage rating visible
Photograph the breaker layout with labels
Note the panel’s approximate age and manufacturer
Note the distance from the panel to where the inverter would likely go
Check for any existing subpanels

Step 5: Identify and Clear Access Points

Assessors need to reach the roof, the electrical panel, the attic (sometimes, to check structural framing from below), and any meter location. An hour of clearing before the visit saves hassle during it.

Clear a path through the garage or basement to the electrical panel
Trim back any shrubbery blocking the meter or the panel’s exterior wall
If attic access is needed, clear stored items away from the hatch
Make sure gates are unlocked and pets are secured
Note any skylights, vents, or chimneys on the roof — these limit usable panel area

Also check for obstructions the assessor wouldn’t otherwise know about: a satellite dish on the roof, a roof-mounted swamp cooler, or a chimney that casts a shadow. Each one removes usable mounting space, and mentioning them saves a return visit.

Step 6: Decide on Your Goals Before the Visit

The assessment produces better results when you’ve already thought about what you want from solar. The assessor will ask, and a clear answer changes the recommended design.

If your priority is lowest upfront cost, ask about a smaller system covering your baseline usage and relying on net metering for the rest.

If your priority is backup power during outages, ask about battery storage — and note that this typically adds $8,000 to $15,000 to the project, so it’s worth deciding before the design stage.

If your priority is maximum independence from the grid, ask about full offset sizing and whether your utility’s interconnection rules allow it.

If you’re planning to move within 5 years, ask about how the system affects resale value and whether a leased or financed system complicates a home sale.

Write your top two priorities on paper. Assessors notice the difference between a homeowner with clear goals and one who hasn’t decided — and the resulting quote tends to be more focused as a result.

Step 7: Prepare Your Questions for the Assessor

The visit is your chance to get information that a brochure can’t provide. Bring specific questions and write down the answers.

Topic	Question to Ask
Roof	Based on what you see, is the roof in good enough condition for the panel warranty period?
Shading	How much production does the shade you measured typically cost?
Electrical	Does my panel need an upgrade, and what would that typically add to the project?
Sizing	What production estimate are you using, and what assumptions drive it?
Timeline	What’s the realistic time from signing to activation, including permitting and interconnection?
Next steps	What do you need from me after this visit, and when will I see a detailed quote?

For a fuller list, our guide to questions to ask a solar installer before signing anything covers the warranty and contract details worth raising later, once a quote is on the table.

Common Preparation Mistakes and How to Recover

You forgot the utility bills. Ask the assessor if they can proceed on estimates and send the bills afterward. Many will, but the quote will be provisional until real usage data arrives.

The panel is behind stored boxes. Don’t panic. The assessor can usually work around clutter, but a clear panel yields a more reliable read on available breaker space.

You discover the roof is older than expected. This is a common and important finding. Ask the assessor to quantify the cost of panel removal and reinstallation if a reroof is needed during the system’s life — typically $1,500 to $3,000 in labor — so you can compare reroofing now versus later.

You’re not sure who owns the roof (shared wall, HOA, condo). Raise this before the appointment. Some installers will pause the process until ownership or HOA approval is confirmed.

Step 8: Confirm Logistics for the Day Of

The assessment itself is short. Make it count.

Confirm the appointment window and who needs to be home
Ensure the assessor can access the roof safely (no ice, no active leaks)
Have your bills, panel photos, and notes gathered in one folder — digital or paper
Set aside the full window; assessments can run long if the roof is complex
Ask for the assessor’s name and the follow-up timeline in writing

After the visit, most installers deliver a detailed proposal within one to two weeks. If you haven’t heard back in that window, a polite follow-up is reasonable.

Quick Reference: Pre-Assessment Checklist

12 months of utility bills downloaded
Current rate plan and planned usage changes noted
Roof age, material, and condition assessed from the ground
Shade mapped at 9 a.m., noon, and 3 p.m.
Electrical panel photographed with amperage visible
Access paths cleared to panel, attic, and meter
Roof obstructions noted (skylights, vents, dish, chimney)
Top two priorities written down (cost, backup, independence, resale)
Questions for the assessor prepared
Appointment logistics confirmed

What to Do Next

Start with Step 1 today — log into your utility account and download a year of statements. It’s the item that takes the longest and unlocks the most value from the visit. Then set a date to walk your roof line from the ground and note your shade patterns at three times of day. That’s two hours of work, and it will make the assessor’s visit roughly twice as productive.

Which step is most uncertain for your situation — the electrical panel, the roof age, or the shading picture? Note where you’re starting from and that will help you decide which questions to prioritize when the assessor arrives.

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