Introduction to Solar Mounting and Attachments
How do solar panels stay on the roof?
Attaching solar panels to your roof is not as simple as buying a pack of nails and hammering away until the panels feel secure.
No, solar panels are classified in the building code as “Components & Cladding,” and consequently, must be fully integrated with the building’s structure.
This means the products used to mount solar panels are attached to rafters and are engineered to handle the same forces and environment as the roof.
Factors to consider in solar mounting
Over the last decade, a number of products have been designed to attach solar panels to a building. But selecting the correct product is going to depend on local and site-specific factors, such as weather and roof style.
For example, homeowners in coastal California do not need a solar array that can handle snow loads or hurricane-force winds. However, they do need to deal with the corrosive effects of sea salt in the air.
Conversely, people in the Northeast must account for both hurricane-force winds and snow loads, as well as the corrosive effects of high humidity and near-marine environments.
What’s in a mounting system?
Solar mounting systems are composed of three parts: (1) roof attachments, (2) mounting rails, and (3) module clamps.
Each of these components can vary in size, weight, and material, so manufacturers typically provide detailed information to aid in component selection and system design.
Some manufacturers even offer free online design tools to help with planning.
For every roof, there’s an attachment
Roof attachments are the base or foundation of any solar array. There are a number of different types and style of solar attachment, each designed for specific roofing materials.
Composition asphalt shingles are the most common roofing material in the US. A number of attachment products for composition shingle roofs are designed to be both a structural anchor and a waterproof flashings. These “integrated” products help reduce the time and cost associated with installing roof attachments.
Tile and slate roofs, on the other hand, require more complex products with more labor-intensive installation procedures. These challenges are compounded by the fact that tiles are fragile and can crack if not handled carefully.
Homeowners with these roof types should expect to pay slightly higher costs when receiving bids from solar installers. As well, it’s a good idea to discuss ahead of time how the installer plans to avoid damage to the tiles or replace them if damage does occur.
Rails of all shapes and colors
Solar mounting rails are typically made of aluminum. Aluminum is strong, lightweight, and corrosion resistant, making it a great material for rooftop construction.
Most rails have an “anodized” finish, which means they have a protective layer on their surface to prevent damage or surface corrosion. This feature ensures a clean appearance long into the future by preventing buildup of oxides on the surface of the aluminum. Preventing this buildup is also key to ensuring any future maintenance of the solar array is easy and hassle-free.
Anodization is available in “clear” (silver) or “black,” depending on the customer’s aesthetic preferences. Rails with a “mill finish” are not anodized, and are best suited for dry, non-marine, non-industrial regions, such as the desert Southwest.
In addition to anodization options, manufacturers frequently offer more than one size of mounting rail. Different sizes are engineered to handle different wind and snow loads.
A large, heavy-duty rail will always provide sufficient structural strength, but it may be more expensive than is necessary. Often, a mid-range or lightweight rail is going to provide more than enough structural strength for mild climates, while also minimizing the cost and weight of material on the roof.
Clamps that “bite,” literally…
The final component of the mounting system is the clamps.
Most clamps are known as “top-down” clamps because they secure the top surface of the solar module to a slot in the mounting rail, which is supporting the module from below. These clamps are very secure, while also being quick to install and making any future maintenance easy to perform.
Newer designs of top-down clamps incorporate “teeth” that bite into the module frame. These teeth are actually making a grounding connection to the module, which provides an additional measure of electrical safety for the solar installation.
Clamps with this capability are all certified to the Underwriters Laboratory test standard 2703.
And luckily, the teeth are small and remain hidden beneath the clamp, avoiding any unsightly “bite marks”.
Always select a trusted supplier
The final and most important component of any solar installation is trust.
Solar installations are designed to operate for decades without major repair. This requires a high degree of confidence in the products and the workmanship, backed by years of experience.
Often, the difference between a reputable company and a low-cost competitor can be difficult to discern. Homeowners should discuss the product and warranty options with their installer in detail. Warranties should be at least ten years, and ideally twenty or more.
Also, make sure that the installer has experience working with the product manufacturer. A trusted supplier will be one that has proven the value of their warranty through years of collaborating with their installation partners.