Roof types

Solar on a flat and low-slope roof

Best for: Low-slope homes, additions, and porches where a tilted rack can face the array properly.

What this roof changes

• Ballasted or mechanically attached tilted racks set the orientation, so a flat roof often produces better than its compass direction suggests.
• Wind uplift engineering matters more here; expect a structural review and possibly a permit conversation about drainage.
• Membrane age is the shingle-age problem in another material. Solar over a tired membrane is expensive procrastination.

How to use these notes before you sign

Bring this page to the quote conversation as a checklist, not a verdict. Confirm how the array will be attached to your material, what that attachment does to any roof warranty, and whether layout limits change the system size you were sold. Then ask the sequencing question out loud: does any part of this roof need work in the next decade, and if so, does that work happen before the panels, with the solar priced around it, or after, with a removal bill attached? Installers answer these questions routinely for homeowners who ask. The expensive projects are the ones where nobody asked until the roof failed under a working array.

The re-roof rule that applies to every material

Panels are a 25-year commitment bolted to a roof with its own remaining life. If the roof surface under the array has less life than the array, you will pay to remove and reinstall the system mid-life, or rush a roof decision later. Get the remove-and-reinstall price in the original contract, in writing, while you still have leverage. Our quote red flags guide lists the other lines that belong in that contract.

Questions worth asking on this material

• How exactly is the array attached to my roof, and does that method preserve my roof warranty?
• What does removal and reinstallation cost if I re-roof during the system's life, and will you put that figure in the contract?
• Does my roof surface have more remaining life than the array, in your written assessment?
• What layout limits does this material impose, and how did they change the size or production estimate you are quoting me?

Once the roof answers are settled, the economics go back to sun, price, and export rules. Price the resulting system in the estimator against the $3.25 per watt benchmark, check your state page for the export rule that values your surplus, and size it with the sizing guide rather than by available roof area.