Duncan Cleminshaw and Reynolds Holmes, GAF Energy

Residential solar in the U.S. has grown substantially over the past two decades, and millions of homes across the country now have rooftop solar systems. Up until this point, residential solar installation has consisted primarily of mounting solar panels on top of the roof. That approach—rigid solar panels mounted on racks that are bolted through roofing shingles—is a somewhat inelegant, brute-force solution that creates engineering, construction, and sales challenges. It’s frankly remarkable that the industry has experienced so much growth with such uninspired installation methods.

While solar is now installed on an estimated 7% of homes across the country, the potential for mass market adoption remains largely untapped. For perspective, consider that approximately 5% of homes in the U.S. undergo roof replacements annually. That is, each year, nearly as many American homes get new roofs as homes that have installed solar in total (over decades).

The functional and perceptual issues inherent to traditional rack-mounted systems limit the industry’s growth. Roof integrity and the additional structural load on top of the house are primary functional concerns, potentially leading to damage and leaks. Bolt-on, racked installation also continues to be expensive and requires expertise to maintain roof integrity. Due to those risks, rack-mounted systems may impact the homeowner’s insurance premiums. And, perceptually, their often less-than-desirable chunky geometric aesthetic can be a concern for many homeowners and communities.

Enter building-integrated photovoltaics (BIPV). With BIPV, waterproofing and energy-generation are solved by one advanced product: a singular solar roof. BIPV in all its forms overcomes limitations inherent in traditional solar rack-mounted systems. This transition to solar technology integrated into roofing shingles or tiles—rather than added on via clunky, unwieldy panels—is inevitable. Fortunately, technological advances and cost reductions have made affordable BIPV a reality in the last several years. Imagine every roof replacement annually becoming a solar roof installation; the growth of solar on U.S. homes would be tremendous.

The benefits of BIPV roofing are many: enhanced aesthetics, increased installation efficiency, and improved structural integration. We must prepare for a landscape where solar technology is not mounted on roofs, but built into them from the outset. BIPV is a superior solution for solar on roofs; the small integrated-solar-roof market promises to outstrip rack-mounted technology in the next decade.
Rooftop solar has traditionally been installed by electricians and solar installers. The shift to BIPV will necessitate adding roofers as a trade not just allowed but required to install solar-integrated roofing. During this transition, manufacturers and contractors will be called upon to engage with permitting authorities to explain how the installation of these roofs meets building codes, and why roofers will be essential to safe and compliant installation of solar roofing.

The Future-Proof Roofing Solution: Combining Technology with Tradition

Take Timberline Solar Energy Shingles from GAF Energy, for example. Timberline Solar incorporates photovoltaic shingles—also known as solar shingles or energy shingles—into conventional asphalt shingle roofs. These energy shingles are engineered to match the characteristics of GAF’s asphalt shingles in size, shape, thickness, weight, and safety certifications, including resistance to wind and fire. Installed using roofing nails—just like asphalt shingles—this system uses conventional tools and processes of shingle roofing.

Many BIPV solar roofs meet building codes and safety standards that classify energy shingles as a roof covering. With Timberline Solar, any design and installation that can use asphalt shingles can now easily include energy shingles.

Simplifying Solar Installation with Roofing Expertise

Because Timberline Solar combines both asphalt and energy shingles, it requires the skills of an experienced roofing contractor to install. As a complete replacement roof, it must be integrated with all features of the roof, including valleys, ridges, hips, eaves, vents, dormers, etc. Each roof feature involves completing roofing tasks that are outside the scope of work performed by electricians and solar installers.

By matching the form, function, and installation method of asphalt shingles, Timberline Solar energy shingles eliminate both the electrical and mechanical complexity of traditional solar, and they instead leverage the tools and practices of shingle roofing.

For example, Timberline Solar has no exposed metal common to retrofit solar installations (module frames, racking, stand-offs, etc.). By removing all exposed metal, Timberline Solar eliminates the grounding and bonding tasks normally performed by an electrician or solar installer.
However, Timberline Solar does not eliminate the need for an electrician; it shifts that role to the point when roofing installation is completed. An electrician will still perform all the post-roof installation tasks of connecting wiring from the roof to the ground and connecting a home’s solar installation to an inverter, the main service panel, and to the utility grid.

Compliance with Codes and Standards

Timberline Solar explicitly complies with the requirements set by the International Residential Code (IRC), which has included photovoltaic shingles since 2012. The IRC has established clear compliance requirements for both the roofing and solar functions of PV shingles. This includes safety standards they have to meet as well as requirements and limitations on how they may be installed. The energy shingle requirements in the IRC are nearly identical to those applied to asphalt shingles.

As a code-compliant roof covering, Timberline Solar has been designed to allow its rooftop installation without enabling any of its electrical functions. Unlike other solar products, the wiring for each energy shingle is always accessible from the top even after it has been installed. No wiring is hidden underneath. This difference matters because Timberline Solar energy shingles can be attached to the roof, and become the roof, without “plugging them in or turning them on.”

It becomes possible to install the entire roof, asphalt shingles plus energy shingles, strictly as a roof covering with a 25-year warranty. Let that sink in. Now ask yourself which trade should be allowed to install the roofing portion of a solar roof.

Protecting the Home, Protecting the Homeowner

Put yourself in the homeowner’s shoes. Your existing roof is at the end of its life. There might even be two layers of roofing up there. Pieces of shingle show up on your lawn after a windy night. Maybe you’ve discovered a couple of leaks in the attic. You look at the 10-day forecast and rain is on the horizon. The point is, you’ve finally decided to bite the bullet and tear the whole thing off. How soon do you need a new roof? Clearly the answer is as soon as possible. Roofs that keep rain out are not optional “nice-to-haves.” They protect the home and the people inside.

Starting from the premise that it’s important to replace a failing roof quickly, what other requirements must be met before work may begin? When it comes to installing one layer of shingles after a complete tear-off of existing roofing, building departments typically issue a permit over-the-counter. The requirements are simple and straightforward.

The inclusion of solar adds other requirements, including electrical plan review, and slows approvals in most jurisdictions. However, the division of labor between roofing and electrical is clear in a Timberline Solar installation, and it is therefore absolutely possible to separate installation into two permits:

  1. The first, issued as quickly as a shingle roofing permit, would allow the installer to complete the roof tear-off and replacement in days, as with a conventional roof replacement.
  2. The second permit, for the electrical, will normally require more time for review, but with the home protected from the weather, the homeowner can rest easy.

The electrical work can be done independent of the roofing, and may begin any time after the permit is issued provided the roof is complete. Depending on the jurisdiction’s preferences, inspections can be performed as each phase of work has been completed, or can be done as a single final inspection covering roofing and electrical.

A building department that chooses to adopt this approach to permitting a PV shingle roof accomplishes two things simultaneously. First, the homeowner (the building department’s “real customer”) and the home are quickly protected from the weather. Second, plan check and permitting are simplified to separate roofing from electrical while still remaining thorough.

Keeping pace with innovation in construction technology is challenging for all stakeholders: AHJs, homeowners, code-making bodies, standards developers, contractors, to name just a few. In this instance, dividing permits for PV shingle roofs between roofing and electrical can fulfill the building department’s commitment to life safety and compliance.

A Word on the Electrical Code

The other code that applies to any residential solar installation is the National Electrical Code (NEC/NFPA 70). Despite the difference in form factor between solar panels and energy shingles, their core function is the same: converting sunlight into electricity.

The electrical code requirements for both types of systems are the same, but energy shingles have the advantage of being simpler because they have no exposed metal to ground, like the frames of the solar panels or the racks they sit on. Nor do they use Module Level Power Electronics, like DC-to-DC converters or microinverters. This allows for clean separation between the roofing installation and electrical work that follows it.

Training and Qualifications for Installers

GAF Energy ensures that all contractors selected to install Timberline Solar receive extensive training including real-world projects. In addition to covering installation and safety requirements specific to Timberline Solar, the training also draws a bright line between roofing scope completed by roofers and electrical scope completed by electricians. A clear division of labor and close coordination between the trades ensures a successful installation.


GAF Energy’s Timberline Solar represents the beginning of a new era in residential solar—one where BIPV roofing will transition from a niche to a mainstream option that many homeowners will choose for their new roof. Opting for solar roofs over regular roofs would represent a step-change in residential solar adoption.

Timberline Solar Energy Shingles are installed just like asphalt shingles. Thus, they remove all of the structural and many of the installation issues that hamstring traditional rack-mounted systems. Given that roofers will be central to the installation of energy shingles, some building departments may determine updates to permitting and inspection processes are needed to account for the differences from traditional retrofit solar.

The introduction of Timberline Solar by GAF Energy calls for a reevaluation of the trades needed to install this hybrid of shingle roofing and solar. Installed as a complete roof replacement, a true BIPV solar roof such as Timberline Solar requires the skills, tools, and training of a roofer. This integration of roofing and solar into a single, cohesive procedure will require the skills of both the roofing and electrical trades for every installation.

During this transition, it is essential for GAF Energy to be at the forefront providing education and support to building departments. Areas of focus should include:

  • Compliance with existing codes and standards
  • Differences from traditional solar in design and installation
  • How roofing and electrical tasks are separated
  • Key areas for inspection

As these systems become more prevalent, a better understanding of their installation processes and the collaboration between roofing and electrical trades will be crucial.

Clear guidelines and proper training will ease the transition, ensuring that energy shingles are easy to permit and inspect, paving the way for a more sustainable future in residential solar energy.