Is My Roof Good for Solar? 10 Years Left, Pitch, Shade Rules

Roof age: the test that matters most

EnergySage says roofs "with more than 10 years of life left in them are often good to go." The stricter standard, from the National Roofing Contractors Association, is a roof that lasts at least as long as the array, which the Department of Energy puts at about 25 to 30 years. Many asphalt roofs, 3-tab especially, cannot meet the strict standard, so the real question is whether you would rather replace the roof now or pay to take the panels off later.

Published ranges; the age of your own roof and its condition matter more than the averages.

Direction, pitch and shade

The National Renewable Energy Laboratory's study of US rooftop potential treats a roof plane as unsuitable if it faces northwest through northeast, is steeper than 60 degrees, or is shaded enough to produce less than 80% of what an unshaded system would. It also needs one unbroken plane of at least 10 square meters (about 108 square feet). In an Energy Information Administration comparison for Los Angeles, a south-facing array produced 11% more a year than a flat one, a west-facing array little more than flat, and an east-facing array substantially less.

Weight

Panels weigh 20 to 50 pounds each, and with racking an array adds about 3 to 4 pounds per square foot, according to Greentech Renewables, which notes that most structures built after 1970 are designed for far more. Snow load, wind uplift and older framing still call for a check, and tile and ballasted flat roofs carry more. The building department has the final say.

Signs the roof needs replacing first

• Granule loss, especially bare patches (GAF).
• Curling, cracked, torn or missing shingles.
• A sagging roof line.
• Damaged flashing at chimneys, vents or walls.
• Rot in the soffit or fascia.
• Stains on interior ceilings or leaks in the attic.

Should I replace my roof before solar, or pay to remove panels later

A typical asphalt roof costs about $14,500, with most jobs between $8,000 and $36,000 (Fixr, January 2026). Taking an array off and putting it back for a reroof adds about $3,800 on average, $2,800 to $4,800 for 14 to 16 panels (Fixr), and more in high-cost markets. In 2021 the Department of Energy cited an NREL estimate that doing roof and solar together averaged about $25,000, roughly $4,000 less than doing them separately. If your roof has fewer than 10 years left, replacing it first is usually cheaper than the detach and reset later.

Already have panels on an aging roof

Plan the reroof around the array instead of waiting for a leak. The removal and reinstall page covers the sequence and cost, and if the system is leased, the lessor has to sign off before anyone touches the panels. The roof leak page covers what to do if water is already coming in.

Solar panels on a shingle roof

Asphalt shingle is the most common roof under residential solar. Each mount is lag-screwed into a rafter through the shingles and flashed, so the work depends on hitting the rafters and flashing every penetration. Shingles last 15 to 40 years (Fixr), which is why shingle roofs are the ones most likely to need replacing during the array's life. The panel lifespan guide covers how long the panels themselves last.