Quick answer
Solar Mounting System A solar mounting system, also called racking, is the set of attachments, rails, clamps and bonding hardware that secures solar panels to a roof or the ground and holds them at a fixed angle against wind and snow.
It also carries the electrical bonding that keeps the metal frames safely grounded. In the US, mounting systems are tested and listed to UL 2703, which covers bonding and the roof fire rating of the panel-and-racking combination.
Quick facts
The key facts about solar mounting system, with sources:
- Also called
- Racking, PV mounting system
- Main types
- Railed roof mount, rail-less roof mount, ballasted (flat roofs), ground mount, pole or tracker
- Safety standard
- UL 2703: mounting, clamping and grounding devices 1
- Also decides
- The system’s roof fire classification with a specific panel 1
- Roof guidance
- Panels perform best facing south at 15–40°, though other roofs can work 4
Key takeaways
- The mounting system, or racking, holds panels to the roof or ground against wind and snow.
- It also forms the metal bonding path that keeps panel frames safely grounded.
- In the US, racking is listed to UL 2703, which covers bonding and the fire rating with a given panel.
- Every roof attachment is a hole that must be flashed to keep water out.
- The racking maker's manual and an engineer's letter set the limits for your roof.
- A licensed solar contractor installs it under a building permit.
What a mounting system does
Panels are flat glass and aluminum sheets. On their own, they would slide off a roof or blow away. The mounting system holds them in place for decades.
It does three jobs. It carries loads, meaning the weight of the panels plus wind and snow, down into the roof framing or the ground. It holds the panels at a set angle. And it connects the metal parts so a fault current has a safe path to ground.
People use "mounting system" and "racking" for the same thing. On your plan set you will see a brand and model name for it.
From rafter to panel
- Roof rafter or truss, the wood beams under the roof
- Attachment screwed into the rafter, with flashing to shed water
- Rail (or a rail-less mount) bolted to the attachment
- Mid and end clamps grip the solar panel frames
- Bonding hardware ties every metal part into one path to ground
How it is engineered for your roof
Every part has a load rating. The IronRidge Flush Mount manual, for example, lists allowable design loads in pounds per square foot (psf) for down, up and sideways forces. It also says actual system capacity is set by an engineer's stamped certification letter.
The designer uses your local wind speed, snow load and roof shape to space the attachments. Higher wind or snow means attachments closer together.
Small details matter. The same manual gives exact torque values for each bolt, measured in inch-pounds, and warns that bare copper wire must not touch aluminum or zinc-plated steel, to avoid corrosion.
Sources: [2]
Types of solar mounting system
| Type | Where it is used | How it holds the array | Watch for |
|---|---|---|---|
| Railed flush roof mount | Most pitched shingle roofs | Attachments into the framing carry aluminium rails; panels clamp to the rails | Number and spacing of roof penetrations; flashing quality |
| Rail-less roof mount | Pitched roofs | Panels clamp directly to individual mounts, with no long rails | Fewer parts, but layout must hit the framing |
| Tilt-up roof mount | Low-slope roofs | Raises panels to a steeper angle | More wind load on the roof |
| Ballasted mount | Flat commercial-style roofs | Weighted trays hold the array, with few or no penetrations | Added dead load; the structure must be checked |
| Ground mount (fixed) | Yards and rural lots | Posts or piers in the ground carry a fixed frame | Trenching to the house; setbacks |
| Pole mount or tracker | Rural and commercial sites | Single pole, or a frame that follows the sun | DOE: trackers cost more up front and need more maintenance than fixed racks 3 |
Example: what one maker's manual specifies
These lines come from the IronRidge Flush Mount Installation Manual, version 3.0 (2020) 2. Other brands publish their own. Your installer must follow the manual for the exact product on your roof.
| Item in the manual | What it says | Why it matters to you |
|---|---|---|
| Standard | Conforms to UL 2703 (2015), first edition | Proves the bonding and fire tests were done |
| Fire rating | Class A system fire rating per UL 2703 with listed module types | Class A systems can go on Class A, B and C roofs without lowering the roof rating |
| Structure | Design loads are minimums; real capacity comes from PE-stamped letters | An engineer, not a sales sheet, decides what your roof can carry |
| Water seal | Certain flashing parts rated to UL 441, for slopes 2:12 to 12:12 | Flashing is tested, but only within its slope range |
| Who installs | Electrical work by a licensed and bonded electrician or solar contractor | Not a DIY job |
| Parts | Use only the maker's parts or recommended parts; substitutes may void the warranty | Mixed parts can void both listing and warranty |
A slope of 2:12 means the roof rises 2 inches for every 12 inches across. Ask your installer for the manual of the racking on your quote.
Where you see the racking on your quote and plan set
- The equipment list: racking brand, rail model and attachment type.
- The attachment plan: a roof drawing showing where each mount goes and how far apart.
- The engineering letter: a structural engineer's sign-off on loads.
- The UL 2703 listing and the fire rating for your panel and racking pair.
- The flashing method and who warrants roof leaks.
Roof mount vs ground mount
Roof mount
- Uses space you already have; no yard taken.
- Shorter wiring to the electrical panel.
- Usually the default on suburban lots.
- Needs no trenching across the yard.
Ground mount
- Free choice of direction and tilt, no roof holes.
- Easier to clean and service.
- Needs open, unshaded land and a trench to the house.
- Takes up yard space and may face setback rules.
Limits of any mounting system
Racking cannot fix a weak or old roof. The DOE advises weighing your roof's age and time to replacement before installing. Taking panels off to re-roof later adds cost.
Roof shape limits layout. Vents, chimneys and fire-access paths can leave less room than the roof size suggests.
Trackers, which follow the sun, make more power, but DOE notes they cost more up front and need more upkeep than fixed racks. On homes they are rare.
What drives mounting cost
We do not list racking prices. They vary by brand, roof and region, and we only print figures we can source.
The drivers: roof type (tile and metal need special attachments), roof pitch and height, the number of attachments your wind and snow loads require, and any structural reinforcement. Ground mounts add posts, concrete or piers, and trenching.
Warranty terms vary by maker. Read the racking warranty and the installer's workmanship warranty, and check who covers roof leaks. See workmanship warranties and cost by system size.
How mounting gets designed, installed and inspected
- A site assessment checks the roof, rafters, shade and space.
- The designer picks the racking and spaces attachments for your wind and snow loads.
- An engineer may stamp a structural letter. The plan set goes in with the permit.
- A licensed crew finds the rafters, installs and flashes each attachment, then rails and clamps.
- Bolts are torqued to the maker's values, and the bonding path is completed.
- The building inspector checks the structure, flashing and bonding during the inspection.
Maintenance over the years
Racking needs little care, but it is not care-free. The IronRidge manual tells installers to re-tighten any loose parts found during periodic checks and to replace any corroded parts right away. It also says routine panel maintenance must not break the bonding path.
From the ground, look for panels that sit out of line, rust stains or loose parts after big storms. Call your installer if you see them.
If you re-roof, the panels and racking come off and go back on. Plan for it with removal and reinstall.
Sources: [2]
Warning signs and when to call a pro
- Water stains on the ceiling or in the attic below the array.
- A panel that sits higher, lower or crooked compared with the rest.
- Rattling or creaking in wind.
- Rust streaks running down from the array.
- Animals nesting under the panels, which can chew wiring.
- Damage after hail or a hurricane. Check your insurance coverage.
Safety rule
Do not climb on the roof to check or tighten racking. Roofs are a fall risk and the array is live in daylight. Call your installer.
What a UL 2703 listing means
UL 2703 covers mounting systems, mounting devices, clamping devices and ground lugs used with photovoltaic modules, for both roof and ground systems 1. Two of its jobs matter most to a homeowner.
The first is bonding. UL Solutions notes that PV equipment must be properly bonded as well as grounded, so that a fault current can flow on the metal and trip the protective devices. A listed racking system lets the clamps and rails form that bonding path, which is checked at inspection.
The second is fire classification. UL 2703 is used to determine the fire rating of a rooftop system made of a specific panel and a specific racking product together, so the roof keeps its fire performance 1. Swapping either part can change that rating, which is why inspectors check the listed combination.
Structural capacity is a separate question: the roof framing has to carry the added weight and wind and snow forces. See solar panel weight and roof loading.
Sources: [1]
Building and electrical codes that apply
Three sets of rules meet at the racking. The building code covers structure, roof covering and fire paths. For homes, that is usually the International Residential Code as adopted by your state.
The electrical code, NEC Article 690 and Article 250, covers bonding and grounding, as the IronRidge manual notes 2. And UL 2703 covers the product listing.
Your local building department enforces the editions it has adopted. Ask which ones apply before design.
Mounting system vs related terms
| Term | What it is | How it relates |
|---|---|---|
| Mounting system (racking) | Rails, mounts, clamps, bonding | Holds and grounds the array |
| Roof penetration | Each hole made for an attachment | Must be flashed and sealed |
| Solar array | All the panels together | Sits on the racking |
| Panel tilt | Angle of the panels | Set by the roof or a tilt kit |
| Solar shingles | Panels built into the roof itself | No separate racking |
Common misunderstandings
- Myth Solar panels always cause roof leaks.
- Reality Each attachment is a hole, but correctly flashed attachments are built and tested to keep water out.
- Myth Any clamp works with any panel.
- Reality UL 2703 listings and fire ratings apply to tested combinations. Swapping parts can change them.
- Myth Racking is just metal, so brand does not matter.
- Reality Load ratings, fire ratings and warranties differ by product.
- Myth Flat roofs need no attachments.
- Reality Ballasted systems can avoid most holes, but the roof must carry the extra weight.
In South Carolina, Georgia and Virginia
South Carolina has the 2021 building codes (2021 IRC and IBC) in force, and the 2024 IRC is scheduled for local use from 1 January 2027 5.
Design wind loads vary by location, so check the wind speed and attachment spacing shown on your plan set. In SC, panel installers register with LLR as Residential Specialty contractors ("Solar Panel Installer").
In Georgia and Virginia, ask your local building department which code edition and wind maps apply.
What to ask about the racking on your quote
Mounting is installed by the solar contractor under a building permit. These questions help you read the plan set.
- Which racking product and attachment are listed, and is the pair with your panel listed to UL 2703?
- How are roof holes flashed, and who warrants leaks: the installer, the roofer, or neither?
- How old is the roof? See re-roof before solar and the roof-first checker.
- Did an engineer or the permit office review the structure, and are any rafters being reinforced?
- Would a ground mount suit your lot better? Compare in ground mount vs roof mount.
Questions about solar mounting system
What is solar racking?
Solar racking is the rails, mounts, clamps and bonding hardware that hold solar panels to a roof or the ground. Racking and mounting system mean the same thing. It also forms the grounding path for the panel frames and holds them at a set angle.
Do solar panel mounts cause roof leaks?
Not when they are installed right. Each roof attachment is a hole that must be flashed and sealed, and flashing parts are tested for water sealing within set roof slopes. Leaks usually trace back to poor flashing or a missed rafter. Ask who warrants roof penetrations before you sign.
Can solar panels be installed without drilling into the roof?
Sometimes, on flat roofs. Ballasted systems hold an array with weight instead of holes, if the structure can carry the load. On pitched shingle roofs, attachments into the framing are the norm. Solar shingles are another option that becomes the roof itself.
What is UL 2703?
UL 2703 is the US safety standard for solar mounting systems, clamps and ground lugs. It covers electrical bonding and is used to set the roof fire rating of a specific panel and racking pair. Inspectors check that the installed parts match the listing.
What is a ballasted solar mount?
A ballasted mount is a flat-roof system that uses weighted trays to hold panels in place instead of bolting into the roof. It avoids most roof holes but adds weight. An engineer must confirm the roof can carry it.
What does a Class A fire rating mean for solar racking?
It is the highest roof fire rating, tested with a specific panel and racking pair. One maker's manual states that a Class A rated PV system can go on Class A, B and C roofs without lowering the roof's fire rating. Check the rating for your exact pair.
How long does solar racking last?
It depends on the product, climate and install quality, so check the maker's warranty rather than a rule of thumb. Aluminum and stainless parts resist corrosion, but loose or corroded parts should be replaced. Ask your installer for the racking warranty in writing.
Can my roof hold solar panels?
Most sound roofs can, but only an engineer or the permit office can confirm yours. They check rafter size and spacing, roof condition, and your local wind and snow loads. Some roofs need extra framing first. See our guide on solar panel weight and roof loading.
Does the racking need to be grounded?
Yes, the metal must be bonded and grounded under the NEC. Listed racking lets the clamps and rails form the bonding path, which the inspector checks. Routine maintenance should never break that path.
Sources
- UL Solutions, PV Mounting Systems Certification (UL 2703), retrieved .
- IronRidge, Flush Mount Installation Manual, version 3.0 (2020), as filed with LA County Public Works, retrieved .
- US Department of Energy, Solar Photovoltaic System Design Basics, retrieved .
- US Department of Energy, Homeowner’s Guide to Going Solar, retrieved .
- HyreSolar SC fact pack: SC Building Codes Council code adoption (2021 codes in force; 2024 IRC scheduled 1 January 2027), retrieved .
Expert review
Written by the HyreSolar Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Standard scope from UL Solutions; ratings, torque, corrosion and installer duties from the IronRidge Flush Mount manual v3.0 (one maker, used as an example); tracker and roof guidance from two DOE pages; SC code status from the SC fact pack.
Mounting-type descriptions are general and name no product; the installer’s stamped plan set governs any specific roof.
Suggest a correction. We fix errors and say what changed.