Will My Roof Work for Solar? The 10-Minute Assessment

Before you invite salespeople onto your roof, spend ten minutes answering one question: is my home even a good candidate for solar? Most of the answer is visible from your driveway, your attic hatch, and your electric bill. Work through these ten checks in order — each one is framed as pass (keep going), caution (solvable, but budget for it), or stop (fix this first). No statistics are invented here; where a judgment call is involved, the check tells you to ask the installer.

The 10 checks

1. Roof age and remaining life. Solar panels last decades, and removing and reinstalling them to replace a roof underneath is expensive. If your roof will need replacement within about five years, do the roof first, then the solar. Pass: roof installed or replaced within roughly the last decade with plenty of life left. Caution: mid-life roof — get a roofer's honest remaining-life estimate before signing. Stop: replacement needed soon — sequence the projects roof-first.
2. Roof material and condition. Asphalt shingle, metal, and tile are all routinely installed on; the installer needs to confirm the attachment method for your material. Pass: sound roof, common material, no active leaks. Caution: older or unusual material (slate, wood shake) — fewer installers handle it; expect higher quotes. Stop: active leaks or structural damage — repair first.
3. Orientation. In the northern hemisphere, south-facing roof planes get the most sun over the year; east- and west-facing planes are workable but produce less; north-facing planes are generally poor candidates. Pass: large south-facing section. Caution: mainly east/west — the system can still work, but get the production estimate in writing and compare it against your usage. Stop: only north-facing usable space.
4. Shading — and its seasons. Trees, chimneys, dormers, and neighboring buildings all cast shadows, and winter sun angles make shadows longer. Check shade at different times of day and remember that a tree that is fine in July may shade the roof in January. Pass: clear sun most of the day, year-round. Caution: partial or seasonal shade — microinverters or optimizers handle it better than a single string inverter; make sure the quote's production estimate reflects real shade analysis. Stop: heavy all-day shade with no option to trim or remove the source.
5. Usable roof space vs. the system size you need. Pull 12 months of electric bills and total your annual kWh — that's the demand your system is sized against. Then eyeball whether your unshaded roof area can plausibly hold that many panels (your installer will do the precise layout). Pass: ample clear roof for your usage. Caution: tight fit — you may cover only part of your bill, which is fine if the economics still work. Stop: far too little space for meaningful production.
6. Roof pitch and structure. Very flat roofs need tilted racking; very steep roofs are harder (and pricier) to work on. Either way, the installer — not you — must confirm the roof can carry the added weight. Pass: conventional pitch, no sagging or soft spots. Caution: flat or unusually steep — expect racking or labor adjustments in the quote. Stop: visible structural issues — get a structural review before anything else.
7. HOA and local rules. Many states limit what HOAs can prohibit, but approvals, aesthetic rules, and historic-district restrictions still exist. Pass: no HOA, or HOA with a clear solar approval process. Caution: HOA with design rules — start the application early; it can take weeks. Stop: a hard prohibition you cannot resolve — verify what your state law actually allows before assuming the HOA wins.
8. Electrical panel capacity. Your main panel must have room for the solar breaker, and very old panels sometimes need an upgrade. Pass: modern panel with open breaker slots. Caution: full panel or older equipment — ask the installer whether an upgrade or derate is needed and get it itemized in the quote. Stop: don't guess — this is the installer's call during the site assessment.
9. Your utility's interconnection and net billing rules. What the utility pays you for exported power shapes the whole financial case — and it varies enormously. California's Net Billing Tariff (NEM 3.0), in effect for new interconnections since April 15, 2023, credits exports below retail; Nevada's NMR-405 Tier 4 credits excess exports at 75% of the retail volumetric rate, locked for 20 years; Florida requires net metering for customer-owned systems up to 2 MW with no fees or mandatory insurance for Tier 1 (≤10 kW). Pass: you've read your utility's current net metering/billing terms. Caution: you haven't — look them up before comparing quotes. Stop: none — but never sign a quote whose savings math assumes export rules you haven't confirmed.
10. When to get a pro site assessment. If you passed checks 1–9, book assessments with at least three installers — the assessment is where a professional verifies roof condition, structure, shade, panel capacity, and interconnection in person. Pass: schedule it. Caution: if any check above was a caution, tell each installer upfront so their quote addresses it. Stop: if any check was a stop, fix that first — a site assessment can't fix a roof that needs replacing.

Free remote tools: check your roof from your desk

Two free tools can estimate your roof's potential before anyone climbs a ladder:

• Google Solar API. Google's Solar API documentation describes buildingInsights and dataLayers endpoints that provide building-level rooftop solar potential: sunlight exposure, roof segments, suggested panel layout, and estimated production. Several consumer-facing solar tools are built on this data — if an installer's satellite estimate looks optimistic, this is the underlying dataset to compare against.
• PVWatts. The PVWatts Calculator estimates grid-connected PV energy production using National Solar Radiation Database data. Enter your address, a system size, and basic assumptions, and you get an independent production estimate — the fastest way to reality-check a salesperson's kWh forecast.

Neither tool replaces the on-site assessment (they can't see your panel's breaker slots or feel a soft spot in the decking), but running both takes fifteen minutes and arms you with independent numbers before the first sales call.

Before you sign: the money side

Once the roof passes, the next questions are financial: lease vs. buy vs. PPA, how to read the quote line by line, and which installer red flags to avoid. Check current state and local incentives on DSIRE — and remember that the federal 25D residential credit is not available for property placed in service after December 31, 2025, so post-2025 purchase quotes should be evaluated at full price. The Treasury's consumer solar guidance is the single best pre-signing read: its comparison checklist (itemized costs, fee increases, guaranteed production with a remedy, warranty terms) catches most bad deals.

Verified: 2026-10-11 — Google Solar API docs provide building-level rooftop solar potential (sunlight exposure, roof segments, panel layout, estimated production) via buildingInsights and dataLayers endpoints; PVWatts Calculator (pvwatts.nlr.gov) estimates grid-connected PV production from National Solar Radiation Database data; DSIRE (dsireusa.org) offers zip-code search for state/local incentives; IRS rule that 25D is not available for property placed in service after 12/31/2025. All linked sources opened and confirmed resolving on 2026-10-11.

This article was drafted with AI assistance and reviewed by the site editor.