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Can I Put Solar on an Old Roof?

Published Jul. 06, 2023

Every week, Citadel’s team of roofing experts assess residential roofs to determine if they are in good enough condition for us to ethically install solar panels on top.

If we tell you your roof needs work, we’re not trying to make more money. We’re trying to make sure you make the best economic decision for your family, while keeping them safe. And we’re being honest with you. We don't want to mislead you about the remaining life expectancy of your roof.

But not all installers take that approach. If you really want to put solar panels on an old or damaged roof, you’ll probably be able to find an installer willing to look the other way and do it.

We’d like to explain how and why roofs sometimes need replacing, to protect your home and your pocketbook, before we can install solar. We’ll detail the types of bad roofing situations we encounter; one may very well match your own. And we’ll present the solutions, because there are always choices.

My roof has a lifetime warranty. How can it need replacing?

Homeowners are often surprised to hear they need a new roof because after all, they haven’t had any leaks. And today’s roofs are promoted as lasting anywhere from 30 to 50+ years, but this is marketing speak. In reality, roofs last from 15 to 20 years on the short side, and 50+ years on the long side. (The lifespan of most roofs can be lengthened by proper, annual roof maintenance.) Bottom line: Roofs do wear out, faster in certain climates, and older roofs often need replacement before going solar.

A major source of confusion is the belief that tile roofs come with a lifetime warranty. This is true, but the warranty applies only to the tiles. The underlayment and waterproofing layer are not warrantied for life, and that’s where the problems usually occur. (Which is why they’re not warrantied for life!)

How do I know my roof really needs replacing?

When it comes to roofs, a visual inspection may tell you there are issues. Look for signs of wear and tear like:

  • Cracked, broken or loose tiles or shingles
  • Curling shingles
  • Spots of bare areas from granule loss on composition shingles
  • Warping or pooling water on a flat roof.

When any of those symptoms appear, it is very likely that your roof may be beyond its service life – especially if you are planning to add a solar system.

If you can’t see any damage or wear and tear, but you know the roof is getting old, it’s time to ask the professionals. Plus, crews up on ladders can make a much closer inspection than you can safely from the ground. For example, we can spot exposed fiberglass on the edge of a shingle, a clear sign the roof is no longer as sound as it should be. On tile roofs, we assess the condition of the underlayment by removing a number of tiles in various sections of the roof.

Because it’s hard to evaluate your own roof, we highly recommend getting several bids and checking references on the potential roofers.

In some cases, you may have 5 to 10 years of life left in your roof. We recommend against installing solar in that situation, as you will be inviting extra costs associated with removing the solar (and then reinstalling the solar) when the time does come to reroof the house.

What are my roof replacement options? And can I repair it instead?

The options differ based on roofing materials, all of which age differently and have different life spans.


Shingle Roof Replacement: We see roofs that are so old and crumbling that there is no choice but to replace them before going solar. In fact, we advise those homeowners to replace their roofs ASAP even if it means postponing the solar. Roofs are that important.

You’ll get the most integrity from your new roof if we tear off the old shingles; inspect the roof deck for water damage, insect damage, dry rot or other issues; conduct repairs if needed; and install new underlayment, weatherproofing and shingles.

Shingle Roof Overlay: Homeowners often ask if they can shorten the process and reduce the cost by installing new shingles over the existing shingles. Citadel crews sometimes do these “overlays” for roofing customers. We prefer replacing the entire roof as it’s critical that the wooden roof decking be kept in topnotch shape to protect your home, and we can’t access the decking when we do an overlay.

Shingle Roof Partial Replacement: We can help keep your costs down by re-roofing only in the area where the solar panels will be installed. If the roof is truly in need of replacement, we’ll always believe it’s in your best interest to replace it all at once. But we understand that may not always be practical or affordable.

Shingle Roof Repair: Although different areas may age slightly differently, if part of your asphalt shingled roof is old, then all of it is old (assuming it was all installed at once). But if only a section of your roof is damaged, perhaps from a falling tree branch or other injury, we can repair only that section before installing solar.

Switch to A Different Material: Homeowners rarely switch from shingle to tile roofs, because their homes weren’t necessarily designed to support tiles, which are roughly four times as heavy as shingles. But when faced with a roof replacement, some people do opt for a new type of roof.


With tile roofs, the “underlayment” is usually where aging causes problems. Even if your tiles appear intact, the felt layer between the tiles and your wooden roof deck (i.e. the top part of your house) can be worn out, which means it’s not as waterproof as when first installed. It doesn’t help that roofs over 20 years old often have a single layer of felt underlayment, which does not wear as well as a double layer.

(Side note on felt underlayment: Citadel always recommends double-felted underlayment on all our tile roofing projects. For minimal additional cost, you get much greater protection. In a lift and re-lay project (see definition below), it’s incomprehensible to us that some roofers will only put down a single layer of felt. Be sure to ask your roofer if they install single or double layer felt.)

Tile Roof Replacement: One option is to re-roof: take off the tile and underlayment, replace them with more modern, more protective materials and enjoy a brand new roof, maybe in a new color.

Tile Roof Partial Replacement: Sometimes we can re-roof only the section of roof where the solar is going – if we are able to find matching tiles.

Tile Roof Repair: Another option is to do a “lift and re-lay”. We remove the tiles, replace the underlayment on the roof deck while performing any necessary repairs, install new double-felted underlayment and replace the original tiles. Typically, a few of the original tiles will be broken and need replacement; we do our utmost to match the original color.

Tile Roof Partial Repair: To accommodate homeowners and help keep costs down, Citadel also offers a partial lift and re-lay approach when feasible, addressing only the area where the solar is going.

Tile Roof Inset: Another creative option the Citadel team offers for tile roofs is to re-roof the section under the solar panels with composition shingles. We remove the tiles from the smallest possible area (while maintaining weatherization integrity), put down composite shingles, and install the solar. We have a specialist for this tricky job, who excels at blending the shingle area into the tile area so the solar panels appear to be in-set within the tiles.

Switch to A Different Material: Faced with replacing a tile roof, some owners decide to switch to composition shingle roofs or metal roofs at that point.


Here are the options for flat, single-ply membrane roofs needing work before solar can be installed, such as mineral-surfaced cap sheets and TPO or PVC roofs.

Flat Roof Replacement: Generally speaking, any severely damaged or old flat roof will need to be replaced entirely before installing solar. We can’t affix solar racking to these roofs when old or weather-worn; the materials just don’t bond the way they should. We have to re-roof.

Tar and gravel roofs, which are actually made of asphalt waterproofing membrane with a gravel surface, aren’t commonly installed here in California anymore. When we encounter one of these, the roof is often too old to make sense for solar. Even if the roof looks okay to the eye—which is often the case since you can’t see underneath the gravel—the gravel may be masking any issues the actual roof membrane is experiencing.

Flat Roof Repair: With the more modern membrane roofs, Citadel crews can often put down an overlay on the existing roof, saving the homeowner considerable money.

Switch to A Different Material: This is not usually an option for California homeowners, because flat roofs can’t support tile or shingles. You could switch to a different type of membrane roof.

Which of the options cost the least?

There’s no simple answer to this. The size of the roof, the difficulty of working on the roof (e.g. how steep is it?), and the roofing materials all impact the cost to replace a roof.

If it’s a repair, the extent of the damage and the size of the area to be repaired, along with the roofing material, impacts the price.

In very general terms, though, replacing a composition shingle roof can be cheaper than replacing a tile or flat roof, depending on the type of shingle you choose.

Tile lift and re-lays are labor-intensive. All the tiles are carefully removed, carefully stacked on the roof, and carefully re-installed. Because of this, they sometimes cost almost as much as a new tile roof—it’s relatively easy and sometimes faster to tear off and dispose of old tiles.

But in some situations, the cost of a lift and re-lay on a tile roof can be similar to a shingle roof replacement.

And partial replacements using any roofing materials can reduce the cost.

What happens if I put solar on an old or damaged roof?

In the worst case, putting solar on a severely old or damaged roof is dangerous, if your worn-out roof can’t bear the additional weight. Most local building inspectors are on top of this though, as your installer should be also. In the best case, putting solar on a compromised roof can prove costly down the road, if your roof develops leaks or other issues that require replacement.

There will always be unethical companies that will install solar energy systems on questionable roofs. Some of those roofs may be fine for years but many will not. If you have any suspicion that your roof is getting old or is damaged but the solar company says it’s fine, trust your instincts. Get second and third opinions. You’ll always be able to dig up a company who will say what you want to hear and put solar on a defective roof. But you’ll also always be able to find reputable companies who will give you straight, honest answers about the condition of your roof, its ability to support a solar energy system for decades, and your re-roofing options.

In the 20+ years our team has been installing solar, we rarely see workmanship issues related to the solar energy systems. What we do see is workmanship issues related to the roof. Sometimes, it’s a roof installed by another company prior to Citadel installing solar on it; sadly for the homeowner, some of those installers have gone out of business. Sometimes, it’s an older roof that the homeowner can’t or won’t repair or replace before putting up solar panels.

Could the condition of my roof impact my solar warranty?

Some solar companies flat out refuse to install solar on a roof with fewer than 15 years of life left in it. Or they’ll install the system but with no warranty. If the installer is not willing to offer any warranty whatsoever on the workmanship, that’s a pretty clear sign that your roof really is no longer sound. Or it’s the sign of a shady installer.

(We’ve also seen questionable installers offer the gimmick of a lifetime workmanship warranty. Those are often the companies that go out of business; a lifetime warranty is worthless if the company isn’t around to honor it.)

And don’t confuse workmanship warranties with manufacturers’ warranties on the solar panels; they are two different things.

At Citadel, of course we prefer to install on roofs with decades of life in them, because taking the solar down to replace the roof later on—while very doable—costs the homeowner several thousands of dollars. And we have refused to put solar on roofs in very bad condition. But we don’t set a hard and fast rule.

If you really don’t want to replace your roof, we will work with you, and adjust our normal 10-year solar Roof Penetration Warranty to a more realistic number for the condition of your roof. We might offer a 5-year, 2-year or 1-year warranty. If you really want the solar and we are not comfortable with any warranty, we ask that you sign a waiver.

Some examples: If your tile roof is double-felted, we may offer the full 10-year warranty given the reliability of those roofs. If your tile roof is, say, 20 years old, and/or has only a single layer of felt underlayment, we’re more likely to offer something along the lines of a 5-year warranty if you won’t or can’t replace the roof first.

Why does Citadel reduce warranties on some roofs?

We like to put ourselves in our customers shoes on a daily basis, so we can offer the best service. In this case, please put yourself in ours. We stand behind our work. Even with the highest-quality equipment and installation methods and crews, something can go wrong. Equipment can fail. A wire can be faulty. And very rarely, a leak can occur where we penetrated your roof to attach the solar racking, even though we waterproofed it using the most reliable materials and methods. Our warranty is there to protect you in those instances. And we are 100% comfortable backing up our own work in that way.

But if we aren’t comfortable with your old or damaged roof’s quality and it springs a leak near the solar through no fault of ours, who is responsible? Us or your roofer? It gets messy. No business can take on responsibility for another company’s product or workmanship. We need to know the roof we’re installing on has integrity and will last for at least a good chunk of the solar system’s 25+ years. If that’s the case, we’ll happily offer our Roof Penetration Warranty for the full 10 years.

Which roof material is best for solar?

Citadel Roofing & Solar installs roofs of almost all types. We also install solar on most of those roof types, and asphalt shingle, tile and flat roofs all work very well.

But if you want to pick a winner for the best roof for a solar energy system, a strong candidate would have to be standing seam metal roofs. The design of these lets us clamp the solar panel racking to the roof—the standing seam part—without creating any penetrations in the roof. Such roofs are expensive and not all that common in California, but they do work great for solar!

Citadel will not install solar directly on the following types of roof, because they’re too fragile:

  • Stone-coated metal roofs (which are designed to resemble tile)
  • Wood shake shingles
  • Clay tiles
  • Lightweight concrete tiles
  • Synthetic tiles.

If you have clay or lightweight concrete tiles and really want solar, we might be able to create an inset of asphalt shingles under the solar, as described in the Tile Roofs section above.

Why should I take Citadel’s word on the condition of my roof?

Our team has been installing quality roofs and solar energy systems for California homeowners for decades; we began as a roofing contractor and our president installed his first solar system in 1999.

In those years, we’ve seen every possible situation, perfected our approach, and learned from our early mistakes. We know what works and what doesn’t. No one can predict with absolute certainty how long your roof will last. But when we evaluate your roof, our recommendations are not based on a wild guess or a wing and a prayer. Our recommendations are based on years of experience and a solid assessment methodology that is usually proven right rather than wrong. We know what good practices are and we stick to them.

So we feel qualified to evaluate your roof, give you an honest opinion about its remaining life, and advise you on your options regarding whether or not to reroof before installing solar.

Nobody ever wants to replace their roof, especially not when they’re also investing in solar. But look at it this way: A sound roof is like an insurance policy for your house. It protects 100% of your home: the structure, the furnishings, the electronics, your treasured belongings and of course your family.

At least since today’s roofs last 30-50 years, when you do re-roof, you can rest easy it will protect you, and support your solar, for a good long time.

More Roofing Resources

  1. Should I Replace My Roof Before Going Solar?
  2. How Cool Roofs Address Climate Change
  3. How Roof and Solar Warranties Impact Each Other

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