Comprehensive Guide to Installing Solar Panels on a Roof

Jan. 06, 2025

Comprehensive Guide to Installing Solar Panels on a Roof

Installing solar panels on your roof can both save you energy costs and reduce your home&#;s environmental impact. Even though there are some DIY solar panel options, installing them is a highly complex project, and you&#;ll still need assistance from an experienced professional. Join This Old House energy expert Ross Trethewey and solar power installer Anukene Warda for a look into the installation process.

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Planning Your Solar Panel Installation

Before you begin the installation process, properly plan your solar panel system. This involves assessing your roof&#;s suitability, determining the number of panels you need, and obtaining the necessary permits.

Assessing Your Roof

The first step in planning your solar panel installation is to evaluate your roof&#;s condition and suitability. In the Northern Hemisphere, a south-facing roof pitched between 30 and 45 degrees is considered ideal for solar panels.

Your roof should be in good condition and able to support the additional weight. You should also identify obstructions, such as nearby trees or buildings, that could cast shadows on your panels.

Determining Panel Quantity and Layout

Once you&#;ve assessed your roof, you must calculate how many solar panels you need and determine how to arrange them. A solar contractor will recommend the best layouts based on your energy consumption, available space, and budget constraints.

Obtaining Permits and Approvals

Before installation, your contractor must secure the necessary permits and approvals. You may need building permits from your city government, electrical permits, and approval from an HOA if you&#;re part of one. You&#;ll also need to get your utility company&#;s signoff to connect the solar panels to the power grid, which may let you sell the energy you don&#;t use in exchange for incentives.

Be sure you have all required documentation before you proceed to ensure everyone&#;s on the same page and avoid costly penalties.

Installing Roof Attachments

The first step in the physical installation process is securing the roof attachments supporting the solar panels.

First, the installer will find the rafters beneath your roof shingles. They&#;ll either use a stud finder or measure from the roof&#;s edge to find the rafters, typically spaced 16&#;24 inches apart.

Then, it&#;s time to install the stanchions for a strong hold on the panels. &#;Essentially,&#; says Warda, &#;what they are is a lag bolt that goes straight into your roof rafters for a good, strong connection, a big flashing that keeps everything watertight, and a stanchion that goes about 6 inches off the roof.&#; Your solar contractor should use roofing sealant around the holes in addition to flashing for the best seal possible.

Installing Solar Mounting Rails

With the stanchions in place, the next step is installing the racking to support the solar panels.

Trethewey and Warda use aluminum rails for their project, securing them to the stanchions with stainless steel bolts. The bolts should be tight enough to stay secure in tough weather conditions.

Each mounting rail must be square to properly align the solar panels. Trethewey and Warda each measure diagonally from the end of the topmost rail to the end of the bottommost rail. Once everything is checked, they install the other rails the same way.

Wiring and Electrical Work for Solar Panels

Before the panels can go on, their electrical conduit and wiring must be in place. A licensed electrician is often the one doing this work.

First, Warda runs conduit from the roof to the home&#;s main electrical panel according to local codes. The necessary wiring will run through them to connect the panels to the electrical system.

Since solar panels generate DC power, you&#;ll need to use an inverter to convert the energy to AC power for your home. Some systems use a central inverter, but these have a major drawback: if one panel malfunctions, the rest of the array can also go down.

Trethewey and Warda use microinverters under each panel to preserve the system&#;s efficiency. Finally, they use six-gauge copper wire to ground the entire system, including the rails.

Mounting Solar Panels

With the mounting system and electrical components in place, Trethewey and Warda install the solar panels. Each panel is bulky and heavy, so lifting them onto the roof is often a two-person job.

Once each panel is in place, Trethewey and Warda connect it to the microinverter and fasten everything to the rails with clips and clamps. Manufacturers commonly specify the torque necessary to hold everything in place.

Completing Electrical Connections for Solar Panels

The final step in the installation process is completing the electrical connections to integrate your solar system with your home&#;s electrical setup. An electrician will run wires from the roof through a new meter that measures solar production and then connect the wires to a new electrical subpanel. Finally, they&#;ll terminate the neutral wire and connect the two hot legs to a standard breaker.

Once Warda makes his final checks, he turns on the system and confirms the meter shows power being produced.

Solar Panel Monitoring and Maintenance

After installation, you&#;ll need to clean the panels regularly. Dust, debris, and dirt can stop them from working at their best. Different manufacturers recommend different methods, but a gentle rinse with water and a soft brush often suffices. Solar contractors can often do the job for you as part of a maintenance plan.

Watch the system for any signs of wear or damage, such as loose bolts, frayed wires, or cracked panels. Addressing these problems early can stop them from snowballing into larger issues.

How Solar Panels Are Attached to Roofs

Roofs have an important job. They keep warmth in and keep everything else out. However, they can&#;t do much else - and unless you have a swanky rooftop restaurant, your roof probably isn&#;t making you any money.

But for many, there&#;s a pretty easy way to put your roof to work and have it save you money - a rooftop solar system. By producing free and clean electricity for decades, solar energy can be a worthwhile investment.

But how do PV panels attach to roofs, and does it matter what kind of roof you have? Will they cause any damage? What happens if you need a new roof after the solar panels are installed? We&#;ll answer all those questions and more so you can decide if a rooftop solar system is right for you.

What We&#;ll Talk About:

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Suggested reading:
8kW Solar Systems: Compare outputs, installers and returns

Solar Panel Attachments for Different Roof Types
- Asphalt Shingle Roof
- Standing Seam Metal Roofs
- Corrugated Metal Roofs
- Flat Roof and Rubber Roofs
Are Solar Shingles Worth It?
Can Your Roof Support the Additional Weight from Solar Panels?
Can Solar Panels Damage Your Roof?
What Happens if You Need a New Roof?
Will Your Panels Be Secure in Severe Weather?

Solar Panel Attachments for Different Roof Types

The solar industry came up with solutions for installing solar panels on nearly all roof materials. Be it the typical asphalt shingles that cover many of the homes in America, or sturdy commercial-grade metal roofs, there&#;s likely a tried and true way to securely mount the panels.

Asphalt Shingle Roofs

Solar panels have been mounted to thousands of homes across America using a lag bolt and flashing. The bolt is attached to the rafters of the roof, tightly securing the solar panels and the racking system.

To ensure there is no possibility of leaking, a piece of flashing is placed underneath the shingle.

Standing Seam Metal Roofs

Standing seam metal roofs are great for installing solar. Not only are they incredibly long-lasting and durable, but there&#;s no need to make any penetrations in the roof when installing the roof mounts.

How&#;s it done? A U-clamp is attached to the raised seam, and the solar panel racking is then attached securely to the clamp.

Corrugated Metal Roofs

Have a metal roof that isn&#;t standing seam? There&#;s an effective way to install solar on that, too.

Solar panels and their racking are attached to corrugated metal roofs with a bracket designed specifically for that roofing type. The bracket fits over the rib and is held into place by the same galvanized screws that your roofing company used to install the roof.

Flat Roofs and Rubber Roofs

Whether EPDM rubber, TPO, or another material, solar panels can also be installed on your flat roofs - without any penetrations. These are called ballast mounts. The solar panels and their racking are held in place on the roof from the weight of cinder blocks.

An added benefit of a ballast mount system is that the panels themselves can be oriented and tilted to maximize production, which isn&#;t possible with other mounting types that are dependent on the angle of the roof they&#;re being installed on.

Are Solar Shingles Worth It?

As manufacturers get closer and closer to making solar shingles widely available, there&#;s been more and more buzz around the topic.

One thing is for certain, solar shingles really look great and can even be indistinguishable from regular roof tiles. However, they are much less cost-effective than solar panels.

According to SolarReviews.com, it would cost $66,000 to $78,000 to install solar shingles on an average 3,000-square-foot roof. In comparison, you could typically install a 20-30 kW system in that price range.

While solar owners in some states may pay high enough rates and use enough electricity to allow the solar roof to eventually pay for itself, it cannot, for now, compete with the cost savings that come with solar panels.

If you&#;re looking for ways to keep your home or business&#;s curb appeal while installing solar panels, check out our blog: &#;How to Design an Attractive Solar System.&#;

Can Your Roof Support the Additional Weight from Solar Panels?

Solar panels aren&#;t exactly big heavy bricks, but they do weigh something - around 2.5 to 2.7 pounds per square feet. Before installing your system, it&#;s a good idea to make sure your roof can support the added weight. In the vast majority of cases - let&#;s say about 95% - solar panels can be installed on roofs that don&#;t need any additional support.

However, to ensure solar panels aren&#;t installed on any of the 5% of roofs that can&#;t support the weight, a third-party structural engineer will evaluate the roof and give their stamp of approval. If needed, additional support can be added.

Can Solar Panels Damage Your Roof?

Most people are wary of holes in their roofs - and that&#;s fair. With the exception of standing seam metal roofs and flat roofs, penetrations in the roof are required to properly mount the solar panels.

However, a properly installed solar system should not cause any leakage, even if penetrations are needed. The industry has been installing rooftop solar for a few decades, and proper measures have been developed to minimize the risk of any water damage happening because they had solar panels installed.

There&#;s even an added benefit - your solar panels can actually protect your roof.

Solar panels act as a shield to the common and unavoidable wear and tear. They&#;re durable and built to withstand much of what Mother Nature throws their way, keeping your roof dry and clean underneath.

The important thing to note is to work with a reputable solar installer. This will ensure you&#;re backed by their warranties, and they&#;ll work to maintain the warranty of your roof.

What Happens If You Need a New Roof?

If you need to replace your roof after you have solar panels installed, you will need to remove and reinstall the solar panels.

Your solar installer should take a look at your roof before beginning the project to ensure it&#;s in good shape. If you need a new roof, you&#;ll want to get that out of the way before installing the solar panels.

While a new roof is never something we get excited about buying, your future self will thank you. If you need a new roof or repairs to the roof that need to be made, your solar panels will have to be removed and reinstalled. This should cost less than the actual installation itself but is best to be avoided if possible.

Will Your Panels Be Secure in Severe Weather?

Yes, your solar panels will be secure in most severe weather. Solar systems will be designed and installed to withstand winds based on your local code wind loading requirements. Most systems are designed to take winds of 90-120 mph.

Your solar system will have to be installed according to local building codes, which are based on your local weather patterns. These codes will dictate a specific speed of wind that solar systems need to be able to withstand

Partnering with a reputable, well-experienced solar installation company will ensure you get a quality system that&#;s backed for years and even decades. You&#;ll be sure to get a solar system that works properly and safely and generates free electricity for 30+ years.

Contact us to discuss your requirements of integrated solar roof tiles. Our experienced sales team can help you identify the options that best suit your needs.

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