The Roof Type That Makes Solar Installation Impossible (And What You Can Do Instead)
The short answer: There is no single roof type that makes solar installation universally impossible, but some roofs come close. The biggest offenders are wood shake and shingle roofs, slate roofs, asbestos cement roofs, and thatch roofs. These four create a combination of fire risk, structural weakness, friability, and drilling problems that can make standard solar mounting either unsafe, illegal, or financially irrational.
However, "impossible" is rarely absolute. In most cases, the real answer is that solar can be installed, but the cost, risk, and complexity rise sharply — sometimes beyond the point where the investment makes sense. This guide breaks down exactly which roofs cause problems, why they cause them, and what realistic alternatives exist.
Why Some Roofs Are Hostile to Solar Panels
Solar panels themselves are not fragile. Modern photovoltaic (PV) modules are designed to withstand hail, wind, and decades of weather. The problem is almost never the panel — it is the interface between the panel and the roof.
Solar installation requires four things from a roof:
- Structural capacity to carry the added dead load (typically 2–4 lbs per square foot for the panels and mounting hardware).
- A surface that can be penetrated or clamped without destroying the roof's integrity.
- Fire safety — the roof must not ignite or spread fire when combined with electrical equipment.
- A lifespan that matches the solar system (25+ years). If the roof fails in 10 years, the solar investment is wasted.
When a roof fails one or more of these requirements, solar becomes difficult. When it fails several at once, it becomes effectively impossible under normal residential or commercial budgets.
The Four Roof Types That Cause the Most Problems
1. Wood Shake and Wood Shingle Roofs
Why it's a problem: Wood shake and shingle roofs are made from split or sawn wood, typically cedar. They are beautiful, traditional, and — for solar purposes — a nightmare.
The core issue is fire risk. Building codes in many regions (including large parts of California, which is also the largest solar market in the U.S.) classify wood roofs as a fire hazard. Adding electrical equipment, conduit, and penetrations to a wood roof increases ignition risk. Some jurisdictions explicitly prohibit solar mounting on wood shake roofs, or require costly fire-retardant treatments that may not satisfy inspectors.
The second issue is fragility. Wood shakes become brittle with age. Walking on them for installation can crack or break them, and drilling through them creates leaks that are difficult to seal properly. The mounting hardware also cannot be reliably fastened because the wood may split.
What actually happens: Most reputable solar installers will decline the job or quote a "roof replacement first" package. If the wood roof is near the end of its life (15–25 years), replacing it with asphalt shingle or standing-seam metal before solar is often the only sensible path.
2. Slate Roofs
Why it's a problem: Slate is one of the longest-lasting roofing materials in existence — often 75 to 100+ years. That longevity is exactly why homeowners want solar on top of it. The problem is that slate is extremely brittle.
Slate tiles crack and shatter easily under foot traffic. A single broken tile can be expensive to replace (matching the color and thickness of old slate is difficult), and a broken tile creates an immediate leak path. Solar installers must walk on the roof extensively during installation, and every step risks damage.
Penetrating slate for mounting bolts is also problematic. The material does not flex or seal well around fasteners, and the risk of cracking radiates outward from the drill hole. Some installers use non-penetrating mounts on slate, but these rely on adhesive or weighted systems that may not meet wind-uplift requirements in all regions.
What actually happens: Solar on slate is possible but usually requires a specialist installer with slate experience — and that is a small pool. Costs can be 30–50% higher than a standard asphalt shingle installation. Many homeowners ultimately decide the risk of damaging a valuable slate roof outweighs the solar savings.
3. Asbestos Cement Roofs
Why it's a problem: Asbestos cement roofing was common from the 1940s through the 1980s. It is durable, fire-resistant, and — as we now know — a serious health hazard when disturbed.
Drilling, cutting, or breaking asbestos cement releases microscopic fibers that can cause mesothelioma and other cancers. Solar installation requires dozens of penetrations. In most countries, any work that disturbs asbestos-containing materials must be performed by licensed abatement contractors under strict regulations.
The cost of abatement alone can exceed the entire value of a residential solar system. In many cases, the legal and financial burden makes solar effectively impossible on an asbestos roof.
What actually happens: The roof must be professionally removed and replaced before solar can be considered. There is no safe shortcut.
4. Thatch Roofs
Why it's a problem: Thatch — dried straw, reed, or grass — is one of the oldest roofing materials. It is also one of the most incompatible with solar for a simple reason: fire.
Thatch is highly flammable. Electrical equipment, even when properly installed, introduces potential ignition sources (DC arcs, faulty connections, overheating). Building codes in most countries severely restrict or outright ban electrical installations on or within thatch roofs. Even if a workaround exists, insurance companies often refuse to cover a thatched home with rooftop solar.
Structurally, thatch also shifts and settles over time, making rigid mounting difficult. And the roof surface cannot be walked on without damage.
What actually happens: Ground-mounted solar is the only realistic option for most thatched properties. Rooftop solar is generally a non-starter.
Comparison Table: Roof Types and Solar Viability
| Roof Type | Main Issue | Solar Viability | Typical Solution |
|---|---|---|---|
| Wood shake / shingle | Fire risk, brittleness | Low to impossible | Replace roof first |
| Slate | Extreme fragility | Possible but expensive | Specialist installer or ground mount |
| Asbestos cement | Health hazard | Impossible without removal | Abatement + replacement |
| Thatch | Flammability | Effectively impossible | Ground mount only |
| Asphalt shingle | Minor — standard penetrations | High | Standard mounts |
| Standing-seam metal | None — clamps attach without drilling | High | Non-penetrating clamps |
| Clay / concrete tile | Breakage risk, but manageable | Moderate to high | Tile hooks and flashed mounts |
What If You Have One of These Roofs?
You are not automatically out of options. Here are the realistic paths forward, ranked from most practical to least.
Option 1: Replace the Roof First, Then Install Solar
This is the most common solution for wood shake, asbestos, and aging slate roofs. If the roof is already near the end of its useful life, replacing it with a solar-friendly material (asphalt shingle or standing-seam metal) and then installing solar in the same project can actually reduce total labor costs. Many solar companies offer "roof + solar" bundles.
When it makes sense: The roof has less than 10–15 years of remaining life, or local codes prohibit solar on the existing material.
Option 2: Ground-Mounted Solar
If you have available land — even a modest yard — a ground-mounted array avoids the roof entirely. Ground mounts are often cheaper per watt than rooftop systems because they are easier to install and optimize for angle and orientation. They also make maintenance simpler.
When it makes sense: Thatch roofs, asbestos roofs, or any situation where roof work is prohibitively expensive. You need sufficient unshaded land and local zoning permission.
Option 3: Solar Carports or Pergolas
A solar carport or pergola places the panels on a new structure rather than the roof. This works well for homeowners who want solar but cannot or will not modify the roof. It also provides shade and can increase usable outdoor space.
When it makes sense: You have driveway or patio space and want a dual-purpose structure.
Option 4: Specialist Installation (Slate and Tile Only)
For slate and clay tile roofs, some installers specialize in non-penetrating or low-impact mounting. These installers use tile hooks, flashed mounts, and careful foot-traffic protocols to minimize damage. The cost is higher, but the roof remains intact.
When it makes sense: The roof is in excellent condition and you are willing to pay a premium for specialist labor.
How to Evaluate Your Own Roof Before Calling an Installer
Before you spend time getting quotes, run through this quick self-assessment:
- What material is your roof? If it is wood shake, asbestos, or thatch, expect major obstacles.
- How old is it? If it is more than 15 years old, replacement may be the smarter path regardless of material.
- What is your local code? Some jurisdictions ban solar on certain roof types outright. Check with your local building department.
- Does your insurance cover it? Call your insurer and ask whether they will cover a home with solar on your specific roof type. Some will not.
- Do you have ground space? If yes, ground-mount may bypass the entire problem.
Frequently Asked Questions
Can solar panels be installed on any roof?
No. Most roofs can host solar, but wood shake, asbestos cement, thatch, and — to a lesser extent — slate and clay tile create significant barriers. The barriers range from safety and legal issues to simple economics.
Is it worth replacing a roof just to install solar?
It depends on the remaining life of the roof and the cost of replacement. If the roof has less than 10–15 years left, replacing it as part of the solar project often makes financial sense because it avoids the cost of removing and reinstalling the solar system later. If the roof has decades of life left, replacement is harder to justify purely for solar.
Can you put solar on a slate roof without drilling?
Yes, in some cases. Non-penetrating mounts use adhesive or weighted systems, but they are not suitable for all wind zones and may not meet local code. A specialist installer can advise on whether non-penetrating mounting is viable for your specific slate roof.
What is the best roof type for solar?
Standing-seam metal is generally considered the best roof for solar because panels clamp directly to the seams without any drilling. Asphalt shingle is the most common and is perfectly suitable. Both offer a good balance of cost, durability, and ease of installation.
Does a thatched roof disqualify a home from solar entirely?
For rooftop solar, yes — in practice. Building codes and insurance restrictions make rooftop installation on thatch extremely difficult or impossible. Ground-mounted solar is the standard alternative.
The Bottom Line
No roof type makes solar absolutely impossible in every situation — but wood shake, asbestos cement, and thatch come close for rooftop installations. Slate is possible but expensive and risky. If you have one of these roofs, the realistic paths are roof replacement, ground-mounting, or a solar carport.
The key is to get an honest assessment before you commit. A good installer will tell you when your roof is the wrong fit — not try to sell you a system that will cause problems in five years.
If you are unsure where your roof falls, start by checking its material, age, and local code restrictions. That will tell you more than any general guide ever can.