6 Things Solar Installers Get Wrong About Mounting System Specs (and How to Avoid Them)

Who This Checklist Is For

If you're an installer or contractor specifying mounting systems for commercial or residential solar arrays—roof mount, ground mount, or both—this one's for you.

I review specs on these systems every week. Over the past four years at Ironridge, I've seen thousands of orders cross my desk, and I've rejected maybe 15% of first-time submissions in 2024 alone. The issues tend to repeat.

This checklist covers six steps I wish every installer ran through before finalizing a mounting system order. (I should add: we're talking about both roof mount and ground mount systems here—the principles overlap.)

Step 1: Match the Rail Profile to the Module Clamp Interface

This is the one that gets missed most often. Installers read 'compatible with standard framed modules' and assume any rail works with any clamp. Not quite.

The interface between your module frame and the rail—where the mid-clamp or end-clamp bites—has specific dimensional requirements. We publish these in our technical manuals for each system (XR10, XR100, etc.). But I've seen orders where the clamp width doesn't match the rail flange thickness. The result? Clamps that either don't engage fully or over-compress the frame.

Check: Verify the clamp manufacturer's spec against the rail flange width and height. This is in the installation manual—don't assume it's standard.

Step 2: Verify Ground Mount Foundation Requirements Against Site Conditions

Ground mount systems (like our Ironridge ground mount) look straightforward. They're not. The foundation—whether concrete piers, driven piles, or ballast blocks—must match the soil conditions. A system designed for Class 4 soil won't perform in Class 2 clay.

I reviewed a project last year where the engineering firm assumed 'standard compaction' for a ground mount array. The geotechnical report later showed poor drainage and frost heave risk. The original foundation spec would have failed within two seasons. Cost us a $22,000 redesign.

Check: Always cross-reference the mounting system's foundation design with a site-specific geotechnical report. Generic assumptions cost real money.

Step 3: Confirm Flashing Compatibility with Roof Type

Roof mount systems require flashing—there's no avoiding it. But not all flashing works on all roofs. Composition shingle? Standing seam metal? Tile? Each has a different interface requirement.

Here's the part that surprises people: Even within the same roof type, the flashing's profile matters. A stepped flashing designed for a 6:12 pitch won't seat properly on a 4:12 pitch with the same tile profile. I've rejected entire batches of flashing because they were spec'd for the wrong roof pitch. (Should mention: this happened with a 50,000-unit annual order—not a small miss.)

Check: Match the flashing SKU to the specific roof material AND slope. Don't rely on 'universal' claims.

Step 4: Calculate Rail Length for Thermal Expansion (Don't Wing It)

Thermal expansion is one of those things every installer 'knows' about but often underestimates. A 40-foot rail run on a dark roof in the Southwest can expand by over an inch between a cold morning and midday heat. That's enough to buckle a mid-clamp if the system doesn't have expansion joints or slotted rail connections.

The conventional wisdom is to 'leave a gap.' That's not specific enough. You need to calculate the expected expansion based on the rail's coefficient of thermal expansion, the expected temperature range, and the run length. Then check if your mounting system accommodates that movement.

Check: Use the manufacturer's published thermal expansion data. If it's not in the manual, ask for it. Installing longer runs without this calculation is a roll of the dice.

Step 5: Validate the Bonding and Grounding Path

This one is mostly code compliance, but it's amazing how often it gets treated as an afterthought. The mounting system must provide an equipment grounding conductor path—either through the racking components themselves (WEEB washers, for example) or through a separate conductor.

I've seen installers assume that because they're using a metal rail system, the grounding path is inherently continuous. It's not. Anodized aluminum is an insulator at the contact points unless you've included bonding hardware. A failed inspection means rework—and that's an expensive lesson.

People think expensive systems deliver better grounding. Actually, systems that are designed and verified for bonding can charge more because they save on installation and inspection headaches (note to self: this is the causation reversal point).

Check: Confirm that every splice, lag, and connection point has a documented bonding method. If your system relies on mechanical joints alone, you're likely missing something.

Step 6: Review the Installation Manual for Your Specific System (Yes, Really)

This sounds obvious, but I can't tell you how many orders we process where the installer tells me, 'I know how these work—just send the standard kit.' Then the kit arrives, and it doesn't include the right brackets for their chosen module. Or the torque specs are different.

Ironridge publishes separate manuals for each system (roof vs. ground, XR10 vs. XR100). They include torque values, rail splice overlaps, clamp positions, and flashing details. Reading them takes maybe 30 minutes. Skipping them has caused more than one delayed installation.

Take the XR100 manual (circa 2024, at least): it specifies a very particular order for tightening mid-clamps to prevent glass breakage. I've had two installers insist they knew better—one ended up with cracked modules.

Check: Download the manual for your exact system SKU before ordering. Compare your planned configuration against the manual's requirements. If there's a discrepancy, call your rep—don't assume.

What to Avoid (Common Mistakes)

Mistake 1: Assuming 'universal' means 'exact.' No clamp, flashing, or rail is universal across every module and roof. Universal usually means it fits a range—you still need to verify the range includes your specific components.

Mistake 2: Over-relying on sales copy. I've read product pages that say 'works with all standard modules.' That's not an engineering spec. Your contract should specify exact compatibility.

Mistake 3: Ignoring the ground mount foundation calculations. A ground mount system is only as good as its anchor. If the foundation design is a generic template, you're assuming the soil is perfect. It rarely is.

Mistake 4: Treating bonding as optional. It's not optional. Per NEC 690.43, you need a documented grounding path. 'It's the inverter's job' doesn't hold up in an inspection.

Final thought: The vendor who says, 'This isn't our strength—here's who does it better' earned my trust for everything else.

Specialize where it counts. A mounting system done right means fewer callbacks, cleaner installations, and more trust from your customers. That's what I aim for in every review.