Short answer: Before adding solar, make sure your roof will outlast the panels’ working life without major work. If the roof is near the end of its life, replace it first, because removing and reinstalling panels later adds cost and risk. Have a roofer inspect the deck, flashing and structure, and coordinate the attachment details with your solar installer.
Key takeaways
- Solar panels sit on your roof for a long time. The roof under them should be in good shape for at least that long.
- If your roof is near the end of its life, a reroof before solar usually saves money and hassle later.
- Every panel attachment is a hole in your roof. Flashing at those points matters.
- Older framing, tile roofs and flat roofs need extra checks before panels go on.
- Incentive and utility rules change often. Confirm current terms with your installer and tax advisor.
Why roof condition matters for solar
Once a solar array is installed, the roof under it is hard to see, hard to reach and expensive to work on. Any leak under the panels means a solar crew has to come out, disconnect and remove part of the array, and then a roofer has to make the repair before the panels go back. That process costs money, takes time and sometimes leads to finger-pointing between the solar company and the roofer.
The simplest way to avoid that is to put panels only on a roof that does not need major work for a long time. That is the one question to answer before you sign a solar contract.
How old is too old for solar?
There is no fixed cutoff, because condition matters more than age. A well-installed roof that is still sound may be fine. A roof showing these signs probably should be replaced or repaired first:
- Shingles with heavy granule loss, curling or cracking, especially on the south- and west-facing slopes where panels usually go.
- Soft spots in the deck, or past leaks you have patched.
- Rusted, lifted or caulked-over flashing at chimneys, walls and vents.
- On tile roofs, underlayment that has reached the end of its life even if the tile looks fine.
- On flat roofs, blisters, open seams or ponding water.
Our roof lifespan guide explains what to expect from each material in Bay Area conditions.
Sequencing: roof first, then solar
| Your roof today | Usual plan |
|---|---|
| Near the end of its life | Replace the roof first, then install solar |
| Middle-aged, with specific problems | Repair the problem areas and flashing first, inspect the deck, then install solar |
| Fairly new and in good shape | Install solar, with the roofer and solar installer agreeing on attachment and flashing details |
| Solar already installed, roof failing | Plan a coordinated remove-and-reinstall with your solar company and the roofer |
If you replace the roof first, tell your roofer solar is coming. That can affect where vents go, whether to add blocking for mounts, and how to plan the layout so roof penetrations are not where the array will sit. Timing the two projects close together also means the permits and inspections line up better.
Structure and weight
Panels and racking add load to the roof. Most modern wood-frame homes can carry a residential array without changes, but older framing, homes with past alterations, and roofs already carrying heavy tile deserve a closer look. Solar installers usually check this as part of their design and permit package. We look at the framing from the attic during an inspection and tell you if anything concerns us.
Flat roofs on San Francisco row houses and commercial buildings are a special case. Ballasted or attached racking on a membrane roof needs protection pads and careful detailing so the membrane is not damaged, and the drainage path needs to stay clear. Our flat roofing guide covers the membrane side.
Attachments and flashing
Every mount is a penetration. On shingle roofs, attachments should be flashed so water is directed over and around the mount, not just sealed with caulk. On tile roofs, installers use specific tile hooks or replacement flashings, and broken tiles around mounts are a common source of leaks. On metal roofs, some systems clamp to the seams without penetrating the panels at all.
Ask your solar installer how they flash attachments on your type of roof and who is responsible if a mount leaks. If we install your new roof before solar, we are glad to talk with the solar company about the details.
Working with your solar contractor
- Ask whether the solar company inspects the roof itself or relies on you to confirm its condition.
- Ask what happens to your roof warranty and theirs if a leak occurs at a mount.
- Ask how they handle removal and reinstall if roof work is needed later, and what that involves.
- Keep your roofing contract, permit records and photos, and share them with the solar company.
We document every roofing job with before, during and after photos in CompanyCam. That record is useful when a solar designer needs to know what is under the surface.
Incentives: check the current rules
Solar economics in California have changed a lot in recent years. PG&E’s net billing rules for new customers changed in 2023, and federal and state incentives have been revised more than once. Because these programs change, we do not quote them. Confirm the current utility tariff, any tax credit and any local rebate with your solar installer and a tax professional before you decide. Make your roofing decision on the roof’s condition, not on an incentive deadline.
Cool-roof rules still apply
If you replace your roof before solar, California’s Title 24 energy code may require a cool-rated roofing product on some reroofs, depending on climate zone and slope. Your roofer handles this as part of the permit. See our post on cool roof technology for how it works.
How we can help
If you are getting solar quotes, a roof inspection first gives you a clear answer: go ahead, repair first, or replace first. We put that in writing with photos. If replacement makes sense, our roof replacement service and financing options can help you plan it before the panels go up. We work throughout the region, including San Jose and Fremont.
Frequently asked questions
Should I replace my roof before installing solar?
If the roof is near the end of its life or has recurring problems, yes. Removing and reinstalling panels later to replace the roof adds cost and coordination.
Can solar panels go on a tile roof?
Yes, but it takes specific mounting hardware and careful handling of the tile. Broken tiles around mounts are a common leak point, so the work needs to be done carefully.
Will solar panels void my roof warranty?
It depends on the warranty terms and who installs the attachments. Ask both the roofer and the solar company how penetrations are handled and who covers leaks at mounts.
Can panels go on a flat roof in San Francisco?
Often yes, using racking designed for low-slope roofs with protection under the supports. The membrane should be in good condition and the drainage path kept clear.
Planning solar? Get a free inspection and written estimate so you know your roof is ready, or call (415) 410-7917.
