How solar racking works

Key takeaways

• A solar racking system mounts panels securely, providing stability and optimal sun exposure on roofs or the ground.

• Racking systems—rail-based, rail-less, ground-mount, and tracking—fit specific roofs, energy needs, and site conditions.

• Proper flashing, secure mounts, and correct tilt angle help performance and shield your home from damage.

It’s easy for the components used to mount your solar panels to your roof to be an afterthought in anyone’s solar shopping journey, but it shouldn’t be. Solar racking systems make a big difference in longevity and energy efficiency.

We created this primer on solar racking systems to help you understand how they work, what they’re made of, and what your options are. You’ll also learn about all of the aspects that need to be considered when designing your solar technology setup to ensure the best results.

What is a solar racking system?

A solar racking system supports solar panels by securing them to roofs or the ground. Its frame, usually made of aluminum or steel, resists weather and holds panels at the right angle for sunlight. With strong mounts and adjustable brackets, this structure ensures stability and maximizes energy capture from your solar array.

Types of solar mounting systems for different site conditions

There are a few types of mounting technologies used in solar racking systems. These include:

• Rail-based mounting system: Some racking systems use metal rails for mounting hardware to clamp to. These are typically used in flat-roof situations where rails can hold panels in a row at a consistent angle.

• Rail-less mounting system: Other racking systems feature hardware that connects directly to the mounting surface, rather than onto rails. For rail-less mounting systems used on flat roofs, mounting hardware positions the panels at the intended angle.

• Flush roof mounting system: Many residential racking systems mount solar panels directly to the roof at the same angle, giving them a low-profile appearance and often requiring less hardware.

Core components of a racking system for solar panels

While the specific components in a racking system vary between different types of systems, many of the essential components are universal across all systems. These include:

• Flashing: Regardless of whether your racking system uses rails or not, installing it requires drilling into the roof surface. Flashing is a protective layer, typically made of metal, that prevents water from entering the installation site and leaking into your home.

• Mounts: The components that attach your racking system to the installation site are its mounts. Sometimes referred to as feet, the mounts attach via a bolt that passes through the flashing into the rafters of your roof.

• Rails: Rail-based racking systems utilize long metal rails that attach to the mounts. The frames of the solar panels are then mounted onto these rails, ensuring a uniform layout.

• Clamps: For racking systems with rails, clamps are used to attach the frames of the solar panels to the rails.

Tracking options to improve efficiency

Many racking systems are fixed systems that secure your solar panels in a single position at all times. However, you can also buy racking systems that offer tracking—the ability to rotate solar panels to follow the movement of the sun and maximize access to sunlight and solar panel efficiency. That can be especially beneficial in off-grid solar energy setups.

While racking systems that offer tracking capability are more expensive, they can generate meaningful increases in energy production for mono and polycrystalline panels. There are two main categories of trackers for racking systems:

• Single-axis trackers: This kind of tracker rotates solar panels east to west along the horizontal X axis. These can boost energy output by 15% to 25%.

• Dual-axis trackers: You can also buy trackers that rotate your solar panels on both the X and Y axes—or, both east to west and up and down. These provide even greater energy yield increases by further increasing sunlight exposure to photovoltaic cells, but also cost more than single-axis trackers.

Structural engineering factors in solar panel racking

When you're setting up solar racking, you need to think through several technical factors to keep your panels and home safe and operating efficiently.

• Load bearing: Your racking system has to support the weight of your solar panels and withstand environmental forces like high winds, heavy snow, and seismic activity. Systems are rated to comply with local building codes and site-specific conditions.

• Roof integrity: If you don't mount your panels properly, you can damage your roof. Flashings are used to seal the bolt penetrations to prevent water leaks, while ballasts can hold assemblies in place without piercing the roof membrane.

• Tilt and orientation: The racking system sets your panels at the best angle and direction for sunlight. The optimal tilt depends on your home's latitude and the season, and in the Northern hemisphere, you want your panels facing south for the best exposure.

Installation stages of a solar racking kit

The specific steps of installing your solar racking kit depend on which kit you use. But each of the individual steps of installing any racking for residential solar panels falls into one of a few stages.

We believe it is important for homeowners to be as informed as possible about every aspect of their solar energy investment. However, this information is for research purposes only and we strongly advise you to leave the racking installation to a professional.

1. Site preparation

You’ll want to ensure that your roof or other installation site is clean and free of debris as your first step. Inspect the entire area where your racking kit will be installed and remove anything that shouldn’t be there.

2. Measuring and marking

The old adage of “measure twice, cut once” is especially relevant when dealing with the roof of your home. Carefully measure the dimensions of your racking system on your roof to ensure it fits as you imagined. Then, mark the locations of the rafters where you’ll install the mounts.

3. Pre-drilling

Drilling holes where your mounting bolts enter the wood in your rafters helps ensure that it won’t split or break when you put the bolts in. Using a flashing panel as a template, pre-drill the sites where your bolts will go.

4. Installing flashing

You’ll need to install flashing panels at each mounting site to prevent water from leaking into your roof. Make sure the holes in the panels line up with the holes you drilled in the last step before securing them to your roof.

5. Installing mounts

After the flashing is installed, it’s time to secure the mounts. Screw the appropriate bolt through the foot of the mount, through the flashing, and into the rafter for each mount.

6. Installing rails (if needed)

If your racking system uses rails, the next step is to install them. These systems come with specialized mounts that provide a way to bolt the rails on or otherwise affix them.

7. Inspection

It is vitally important that you inspect your racking system before you start mounting your solar panels. Check each mounting site to ensure there are no gaps or holes that could result in water leaks. Ensure that all mounts and, if you have them, rails are fastened securely, with all hardware tightened properly.

Solar racking details

Here’s a detailed table with different types of solar racking components and configurations:

Term or component	What it is	Usage context
Fixed-tilt racking	Stationary mounting system with panels set at a fixed angle	Simple, cost-effective
Adjustable-tilt racking	Allows manual seasonal angle adjustments to optimize sun exposure	Moderate cost, increased output
Single-axis tracker	Motorized system that moves panels east to west throughout the day	Higher energy yield, more complex
Dual-axis tracker	Follows both sun elevation and azimuth for maximum exposure	Highest yield, most expensive
Roof-mount system	Mounts directly on residential or commercial rooftops	Space-saving, common in cities
Ground-mount system	Panels mounted on a structure anchored to the ground	Best for open land, easy access
Ballasted mount	Uses weights (not roof penetration) to hold panels in place on flat surfaces	Ideal for flat commercial roofs
Pole mount	Panels attached to a single or multiple poles, can be fixed or tracked	Elevated, good for uneven terrain
Rail-based system	Uses metal rails to align and secure panels	Standard design, strong support
Rail-less system	Direct-to-roof mounting system without long rails	Lightweight, faster installation
Tilt leg kit	Used to angle flat-mounted panels toward the sun	Small-scale optimization
Flashing	Waterproofing component used where mounts penetrate a roof	Leak prevention

Bottom line on solar racking systems

The racking system that supports your solar panels is a key part of your solar setup. Roof type, home location, the solar panels you pick, and your own preferences all play a role in which racking system fits your needs.

Racking options: You’ll need to weigh the costs and benefits of racking systems that offer tracking capability, which can boost energy output but may add to your upfront costs. Your choice of racking directly affects how stable and efficient your solar array will be, so it’s worth taking the time to compare your options carefully.

And if you decide solar isn’t working out after you crunch the numbers, that’s alright. Solar isn’t best for all homes, climates, or energy markets.

FAQ about solar racking

Below are a few frequently asked questions about solar racking:

What does racking mean in solar?

Racking in solar energy refers to the mounting system you use to keep solar panels securely attached to a surface, like a roof or the ground, ensuring stability and proper alignment.

How far apart should solar panel rails be?

Generally speaking, the rails for solar panel racking should be between three to five feet apart. The specific distance depends on structural elements of your roof and the specifics of your racking system, which can be determined by your solar installer.

How are solar panels attached to rails?

Solar panels are attached to rails with metal clamps. These clamps are designed to hold the rails at one point and attach to mounting hardware on the other.

How many brackets for a solar rail?

Your solar rail racking system should have at least four brackets to be mounted securely. Depending on the size and structure of your racking system and solar panels, you may need to install more.

What equipment does racking hold in a solar setup?

Do you need racking for solar shingles?

Solar shingles take the place of traditional shingles and do not require racking to be installed on your roof. However, they may require specialized fasteners to be mounted properly. Solar shingles usually use thin-film solar panels.