At Haven Energy, our goal is to help you power your home with clean, reliable energy. But in some cases, a roof’s condition or structure may make it unsafe or unfeasible to install solar panels in its current state.
This article explains the components that make up your roof and outlines the most common reasons a roof may not qualify for solar — and what your options are if that happens.
🏠 What Makes Up a Roof?
Before diving into eligibility, it helps to understand what goes into a roof system. Every roof has multiple layers and features that impact its ability to support solar:
- Roof covering: The visible outer material — such as asphalt shingles, clay tiles, metal, or wood shakes.
- Underlayment: A protective waterproof barrier beneath the roof covering that prevents moisture damage.
- Roof decking: The wood sheathing (often plywood or OSB) that forms the surface to which everything is attached.
- Structural framing: The rafters and trusses that support the entire roof.
- Flashing, vents, chimneys & skylights: Additional features that can impact panel layout and water integrity.
Each of these components must be in good condition and compatible with solar mounting hardware.
When Re-roofing May Be Necessary
There are a few primary situations where re-roofing may be recommended to ensure your home is ready for solar. Below, we’ll outline each category and explain the key factors our onsite roofing assessments look for.
🔧 End of Life Condition
Solar panels last 25+ years, so your roof must be in good enough shape to last that long without needing replacement. This includes both the top layer and underlayment layer. Even if your shingles look fine, a failing underlayment can lead to water intrusion beneath the solar array — which can damage both your roof and the solar system. If we see signs of underlayment failure (especially on older roofs), we’ll likely recommend re-roofing.
Common disqualifiers:
- Roof is 20–25+ years old
- Missing, curling, or cracked shingles or tiles
- Evidence of leaks, sagging, or rot
- Damaged or deteriorated underlayment that compromises waterproofing
- Ponding water or soft spots underfoot
🧱 Incompatible Roof Type
Not all materials work with solar mounting hardware. Some can’t be drilled into safely or are too fragile for installation.
❌ Roofing Types Not Compatible with Solar:
- Wood Shake, including those with metal or shingle overlays
- Stone-Coated Metal Roofing
- Clay or terracotta tiles (brittle, high risk of cracking)
- Foam Roofing Systems
- Tar and Gravel
- Lightweight Concrete, Clay Tile, or Two-Piece Cemented Tile
- ⚠️ Exception: These may be acceptable only if reroofed using a Ridge-to-Eave Composition Shingle Inlay System on all solar-facing slopes. No exceptions.
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- Solar and roofing must be installed at the same time in these cases.
Deteriorated Decking
Roof decking is the structural layer—usually plywood or wooden planks—installed directly beneath your roof’s shingles or tiles. It forms the solid foundation that supports the roofing materials and ensures your home stays protected from weather.
Over time, decking can weaken due to age, moisture, improper ventilation, or past leaks. When decking deteriorates, it can no longer provide a safe, stable surface for roofing or for mounting solar equipment.
Common signs that decking may need to be repaired or replaced include:
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Soft or spongy spots felt when walking the roof
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Visible rot, mold, or moisture staining on boards
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Warped, sagging, or uneven sections of the roof surface
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Broken, cracked, or delaminated plywood
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Holes, gaps, or missing sections of sheathing
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Persistent leaks or water intrusion inside the home
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Nail pops or shingles that won’t stay fastened properly (often caused by weak decking beneath)
If these conditions are found during a site assessment, redecking (replacing compromised boards) may be necessary to ensure a safe, long-lasting solar installation.
📐 Insufficient Structural Support
Solar panels add significant weight to your roof. If the underlying structure isn’t strong enough, it may not pass local safety or building codes.
Common disqualifiers:
- Undersized or damaged rafters or trusses
- Evidence of water, termite, or dry rot damage to the framing
- Flat or older roofs not built to modern load-bearing standards
What can be done:
Structural reinforcements may be possible in some cases, though they may add cost and complexity.
🧩 Complex Roof Design or Layout
Why it matters:
We need clear, contiguous space to install panels efficiently and safely.
Common disqualifiers:
- Multiple small roof sections or steep pitches
- Dormers, skylights, and chimneys creating obstructions
- Not enough usable square footage for a system that meets your energy needs