Is My Roof Good for Solar?

The five things that matter

A "good roof for solar" is one that scores well on five dimensions:

• Age and remaining life — does it have enough years left to outlast the panels?
• Material — can panels be mounted to it without compromising the roof or voiding warranty?
• Orientation — which way do the planes face?
• Pitch — what's the slope?
• Shading — what casts shadows on it during the day?

Each one alone can disqualify a roof or push you toward a non-roof solution like a ground-mount array. Together, they tell you whether to install now, install later, or look at alternatives.

Age: the most overlooked factor

Solar panel warranties run 25 years. Removing and reinstalling a solar array to do a re-roof costs $3,500–$8,000 depending on system size. That math drives the rule:

Your roof should have at least 15 years of remaining life before going solar. Less than 15 years and you should re-roof first or accept the future removal cost.

Typical roof material lifespans:

• Asphalt 3-tab shingles: 15–20 years
• Asphalt architectural shingles: 25–30 years
• Metal roofing (standing seam, painted steel): 40–70 years
• Clay or concrete tile: 50+ years
• Slate: 75–100+ years
• Wood shake: 25–30 years (rarely solar-suitable; see below)
• TPO / EPDM flat roofing: 20–30 years

For asphalt — by far the most common — if your roof is over 10 years old, get a roof inspection before a solar inspection. If your installer doesn't ask the roof age unprompted, that's a small red flag.

Material: what's mountable, what's tricky, what's no

Orientation: which direction your roof faces

In the Northern Hemisphere, the production hierarchy is:

• South-facing: 100% of optimal production. The textbook answer.
• Southwest or southeast: 92–98%. Functionally identical to south for most homeowners.
• West-facing: 80–88%. Gets afternoon sun. In TOU rate states, the production timing actually beats south-facing in some scenarios because evening peak rates are higher.
• East-facing: 78–85%. Morning production. Less aligned with peak rates.
• North-facing: 60–70%. Generally not worth installing in residential applications, but technically functional.

Most U.S. homes have multiple roof planes facing different directions. Modern installers will use as many of the suitable planes as needed to hit your production target. East + west splits ("dual-pitch") are common and produce well.

Pitch: the slope angle

Optimal pitch for annual production roughly equals your latitude — so ~30° in Florida, ~40° in Pennsylvania, ~45° in Maine. In real life, almost nobody re-roofs to match. The sensitivity is forgiving:

• Pitches between 15° and 45°: Within 5–8% of optimal. Don't worry about it.
• Flat roofs (0–5°): Mount with tilted racks (10–20° tilt). Adds cost, slightly increases maintenance, slightly reduces row spacing efficiency.
• Steep roofs (45°+): Producing fine — but installer labor cost rises sharply due to safety equipment and slower work pace.
• Very steep (60°+): Some installers won't touch it; others charge significantly more.

Pitch matters less than orientation, and orientation matters less than shading.

Shading: the quiet killer

Shading is the #1 cause of underperforming solar systems and the #1 source of disagreement between bid estimates and real-world production. Even a small amount of shade on one panel can knock out the entire string in a string-inverter design. Microinverters and DC optimizers reduce this dramatically (see inverter types) but don't eliminate it.

Common shade sources:

• Trees on your property — the most common, and the only ones you can do anything about
• Trees on neighbors' property — solar access laws vary; in most states, you have no recourse
• Your own house — chimneys, dormers, second-story walls, plumbing vents
• Neighboring buildings — taller homes on the south, especially in dense neighborhoods
• Future construction — vacant lots, pending developments. Worth checking.

Roof condition checks before solar

Beyond age and material, your roof should be physically ready:

• No active leaks or repairs needed. Solar mounting goes through the roof; existing weak spots become problems.
• Decking in good condition. Lag bolts need solid wood to anchor into. Rotten decking means mounts can't hold.
• No major granule loss (asphalt shingles). Granule loss is a sign the shingle is near end-of-life.
• Flashing intact around chimneys, vents, valleys. Existing flashing problems compound when penetrated.
• Adequate ventilation. Solar panels reduce attic temperatures slightly, which can interact with existing ventilation issues. Usually a non-issue but worth checking.
• HOA/architectural review. Many HOAs require pre-approval. Solar Rights laws (in CA, AZ, NV, FL, NJ, MA, others) limit what HOAs can prohibit, but they can still require specific approval processes.

When to consider a ground-mount instead

Roof not suitable? You may have other options. Ground-mount arrays make sense when:

• Roof is too old, too small, too shaded, or too oriented-poorly
• You have land — typically ¼ acre or more available
• You can run conduit reasonably from the array to your service panel (under 200 feet ideal)
• Local zoning allows it (most rural and suburban does; urban often doesn't)

Ground-mount cost: typically 10–20% higher per watt than rooftop due to racking, trenching, and additional permitting. But the array can be perfectly oriented and pitched, and roof age becomes a non-issue. For homeowners with land and trees, this is often the right answer.

Solar shingles vs traditional panels

If your roof is at end-of-life and needs replacement anyway, solar shingles (Tesla Solar Roof, GAF Energy Timberline Solar, CertainTeed Apollo II) become a viable alternative to "new roof + traditional panels." Honest assessment in 2026:

• Cost: Solar shingles cost roughly 1.5–2.5x more per watt than traditional panels + new roof. Aesthetic premium.
• Production: Slightly lower per square foot than crystalline silicon panels. Often need more roof area to hit the same kW.
• Warranty: Generally good (25 years on the product, 25–50 on the roof portion depending on brand).
• Installer ecosystem: Smaller. Service after a few years is harder than for traditional panels.

Best fit: high-end homes where aesthetics matter, roofs that need replacement anyway, and homeowners willing to pay the premium. Not the answer for value-driven shoppers.

The pre-solar checklist

Before you accept any solar bid, confirm:

• Roof age ≤ 10 years (asphalt) or 15 years (other), OR you've decided to re-roof in the same project
• Roof material is on the supported list for your installer
• At least one roof plane has southern, southeastern, southwestern, or western exposure
• Pitch is 15–45° (or you've accepted ballast/tilt-frame for flat)
• TSRF (or comparable shading metric) is 80% or higher
• Roof has been inspected for leaks, decking issues, granule loss, and flashing condition
• Any HOA pre-approval has been obtained
• Permitting authority has weighed in on rapid shutdown, fire setbacks, and other code requirements

Frequently asked questions