The hardware that attaches solar panels to your home is important because it protects both the solar energy system and your roof. These components are typically called mounting and racking systems — the terms are sometimes used interchangeably but racking specifically refers to rooftop installations.
Key Factors to Consider with Roof Racking
Solar mounts can be fixed onto an existing roof or integrated into a newly built roof. For homeowners in the Northern Hemisphere, South-facing roof surfaces are recommended for high sun exposure. Facing directly East or West are usually the next-best options — an installer can advise you on the best layout for your home. Solar panels can also be installed on the ground when the roof is not an ideal location.
Types of Roofs
Pitched roofs are the most common in homes, though some have flat roofs. The pitch, also called the angle or slope, and composition of your roof will influence the type of racking mounts you can use.
Penetrating or Ballasted Mounts
Most pitched roofs use penetrating mounts. Penetrating or penetration mounts fix the racking to the rooftop with carefully drilled holes, bolts and screws. Specialized panels known as flashing are typically attached tightly to the roof’s surface around the hole to create a watertight seal. The solar panels are then clamped onto rails or other hardware secured to these roof connections. Panels can be installed flush along the roofline or can be tilted in an attempt to optimize performance. Maximum sunlight will hit panels positioned with an angle tilt that approximately equals the site’s latitude.
Many racking systems use rails to support rows of solar panels. Within this setup, panels are usually arranged vertically, and each is attached to two rails with clamps. The rails hold the panels off the roof by several inches, allowing air to flow through and cool them. Overheated solar panels can lose efficiency. In a shared-rail system, two rows of solar panels that would normally sit on four rails share a middle rail and so require only three. This reduces the amount of roof penetrations and the weight of the system.
In a railless penetration mount, solar panels are directly attached to the roof without rails — essentially, the solar module frame acts as the rail. This option requires the same amount of connections and penetrations as systems with rails but offers greater flexibility in terms of panel position and orientation. It can reduce the required labor and visual impact of the installation; however, air flow between panels is reduced, which can cause overheating and reduce performance.
Ballasted and Non-Penetrating Mounts
Ballasted mounts are used on flat roofs, which are uncommon in homes. This type of mount is held in place not through penetration but through the weight of concrete blocks sitting in ballast trays. The panels can be tilted to increase sun exposure.
One option for a non-penetrating mount on a pitched roof is a system that uses strain-based loading. In this case, the racking systems are draped over the roof’s peak, distributing the weight evenly without breaking the surface. The Solar Pod Crown is an example.
Racking for Specialty Roofs: Metal and Tile
The surface and makeup of your roof will affect the types of racking components that can safely be installed. If rather than the typical asphalt or composite, you have a standing seam metal or clay tile roof, specialty mounting systems are available. With a standing seam metal roof, panels are attached with a system that clamps directly to the seams without penetration. While roof penetration is possible on a clay tile roof, it can lead to tile breakage. In contrast, non-penetrating replacement mounts that are shaped like the clay tiles can be integrated into the roof without drilling.
Grounding and Bonding
Grounding and bonding products are also often integrated into solar racking installations. This type of hardware ensures electricity moves safely between components of the solar panel installation. Solar systems are grounded to the earth in case of lightning or line surges. All the metal parts are bonded or joined together to form an electrical path that can safely conduct any fault or abnormal current. Electrically conductive materials and equipment are required by the National Electrical Code to have bonding and grounding systems to limit and control electrical currents. Companies can test their products to prove compliance with safety standards produced by certification company UL, as have the solar racking companies listed below. Some of these companies produce proprietary parts that streamline safe grounding and bonding processes, such as rails that are bonded and connecting elements called grounding lugs.
Solar Racking Companies
IronRidge offers mounting systems for roof and ground-based setups. Its pitched-roof mounting systems come with a “FlashFoot 2” streamlined roof attachment. It offers universal fastening objects (“UFOs”) which work with a wide range of module frame heights and bond with the module frame and rail. It also sells “XR rails,” which have a curved profile and which the company says are stronger and require fewer roof penetrations. These products come with a 20-year warranty.
SnapnRack sells mounting systems for roof and ground-based scenarios. Its key roof offering is a “100 Roof Mount System,” which has bonded rails and includes a proprietary grounding lug. Its site also advertises new features including an array skirt – a feature that streamlines the appearance of the system — and a universal wire clamp. A 20-year warranty is included.
ProSolar makes components for roofs as well as ground installations. Its “RoofTrac” system for pitched roofs is advertised as affordable and comes with a decorative front skirt. This racking system is self-bonding and includes a specialized clamping system that fits any of the company’s rails. It sells roof attachments for standard roof compositions as well as tile and provide a five-year warranty.
UniRac also provides both ground and roof solutions. Its “Solarmount” system for pitched roofs comes with universal clamps and the “Flashkit Pro” roof attachment system, which was designed in partnership with EcoFasten. This design has a rail-joining splice or connector with integrated bonding that eliminates the need for lugs and other components. It also offers a “Sunframe Microrail” model that promises quick installation. UniRac products have a 25-year warranty.
Ecofasten focuses on roof-mounted solar, offering a variety of hardware for composition shingle, metal, tile, slate, structural insulated panels (SIPs) and low-slope roofs. “Rock-It System 4.0” is the latest lightweight version of Ecofasten’s railless system and it offers quick installations on composition shingle and tile roofs. The “SimpleBlock-PV” design can be customized into a rail-free or rail-based version, both with integrated bonding, for standing seam roofs. It warranties its products for 10 years.
Quick Mount PV produces rooftop solar mounting solutions for roofs made of many types of materials. One of its principle offerings is the “QuickRack,” a railless roof mount system. It has a flashing-integrated base mount with patented “Elevated Water Seal Technology.” This design has integrated grounding, allowing an array to be grounded with a single lug. It’s promised to be quick and easy and can be installed with a half-inch socket wrench. Quick Mount PV offers a 25-year warranty.
Mounting Systems From Panel Companies
Some solar panel companies offer their own mounting systems. For example, Canadian Solar sells several residential solar power kits that include panels, an inverter and a mounting system. JinkoSolar offers a roof mounting system for tin and corrugated steel roofs as well as ground mounting hardware. SunPower produces total home solar systems that come with the “InvisiMount” frame. It offers minimalist design and the site explains the “Equinox” system has 70 percent fewer visible parts than conventional systems of the same size. Tesla has announced an entire solar roof system with four varieties of glass solar tiles and an integrated battery.
It’s important to find out if your racking choice will comply with or void your roof warranty. Some solar racking systems have already earned preapproval from roofers as acceptable within their warranties. For example, Quick Mount PV’s products are approved by several leading roofers, including Owens Corning and GAF.
While most homes have rooftop solar, ground mount systems are viable if there is enough available land with plenty of sun exposure. These can be of two varieties: fixed tilt or tracking. In fixed tilt systems, panels are tilted at a fixed angle, again based on the site’s latitude, to achieve the highest possible exposure to solar irradiance from a stationary position. Tracking systems have a motor that shifts the panels so they track or follow the movement of the sun. These produce more electricity per panel but cost more and require more land.