Types of Solar Mounting Structures: Roof, Ground and Floating

Main Types and Subtypes of Solar Mounting Structures

Some published lists count five types, separating top-of-pole mounts, side-of-pole mounts and tracking systems from standard ground mounts. All three still pass their loads into foundations in the ground, just as fixed-tilt racking does. This article treats them as ground-mounted subtypes, along with carports and agrivoltaic structures that leave room for parking or farming. Wall-mounted, balcony and building-integrated photovoltaic (BIPV) systems fall outside the three families covered here.

Roof Mounting Structures by Roof Type

A roof-mounted array relies on two parts of the building. The covering dictates how the structure attaches. The framing underneath limits how much extra weight the roof can carry and how much uplift each support can resist. If your roof covering is near the end of its life, re-roofing before installation avoids having to remove and reinstall the array later.

Standing Seam and Trapezoidal Metal Roofs

On a standing seam roof, seam clamps grip the raised seams, leaving the roof sheets free of fastener holes. Klip-Lok, a common concealed-fix profile, has non-penetrating clips with jaws shaped to its ribs. Each clamp has to match its roof profile, because holding capacity measured on one profile does not transfer to another.

Trapezoidal and corrugated sheet roofs need attachments that go through the sheet. Aluminum mini-rails are screwed to the ribs, or hanger bolts pass into the purlins and carry an L-foot for the rails. Purlin-fixed hanger bolts give the load a direct path into the building frame. Sheet-fixed mini-rails depend on the sheet and its existing fasteners, and sheet thickness and screw pull-out capacity set the attachment spacing.

Tile and Shingle Roofs

Tile hooks are fixed to the rafters and pass between the overlapping tiles to carry the rails, with the hook arm clear of the tile below. Asphalt shingle roofs, common on North American homes, use L-feet lagged into the rafters through a flashing that sheds water around each penetration. Arrays on both roof types are usually flush-mounted, parallel to the slope.

Ballasted, Attached and Hybrid Flat Roof Systems

On flat roofs with only a slight slope, the array can be held down by weight alone. In a ballasted system, concrete blocks sit in trays on the racking: their weight resists uplift, and friction against the roof surface resists sliding. The trade-off is permanent dead load from the modules, racking and ballast. That weight bears on the roof as a concentrated load through the protection pad under each base.

Mechanically attached systems anchor the racking to the deck or framing and add far less weight, but each anchor needs a flashed penetration. Hybrid layouts combine the two. Ballast typically holds down the interior of the array, and anchors go in near the edges and corners, where airflow separates from the roof and uplift peaks.

Fixed, Tracking and Elevated Ground Mounting Systems

Whatever the subtype, a geotechnical investigation of the soil, rock and groundwater narrows down the foundation types the site can use. Driven piles and ground screws suit most soils. Rock or cobbles may call for pre-drilling or concrete. On ground that must not be penetrated, such as a capped landfill, ballast blocks take over.

Fixed-Tilt Ground Racking and Pole Mounts

Fixed-tilt racking holds the modules at a set angle on single-post or dual-post frames. Latitude gives the starting tilt, but a steeper array catches more wind and casts a longer shadow on the row behind. Rows end up farther apart, and less capacity fits on your site. For that reason, tilt angle, wind load and row spacing are worked out together.

Pole mounts carry a small array on a steel pole, either on top of it or clamped to its side, and suit off-grid and compact installations. With the whole array on one support, that single foundation takes the full overturning moment from wind.

Single-Axis and Dual-Axis Trackers

Horizontal single-axis trackers, which turn rows about a north-south axis, are the standard choice for large plants in many markets. Dual-axis trackers remain a niche option. In the United States, Berkeley Lab's 2025 data update found that 99% of new utility-scale PV projects in 2024 used single-axis tracking.

Then why use fixed-tilt racking at all? Because trackers only pay off on the right site. Each row rotates on a straight torque tube carried by closely aligned piles, and steep or uneven ground makes that alignment hard to hold. Drives, bearings and controllers need regular maintenance, and the rows rely on a stow mode that turns them to a protective angle in high wind. How much extra energy single-axis tracking delivers depends mainly on the share of direct sunlight at the site.

Carports and Agrivoltaic Structures

A solar carport has to clear vehicles and keep its columns out of stalls and drive aisles. Single-column cantilever frames carry the canopy on one row of columns, and two-column frames suit heavier snow or wind loads.

Agrivoltaic structures make room for crops, livestock or farm machinery. Germany's pre-standard DIN SPEC 91434 classifies them by where the farming takes place. Category I covers overhead systems that leave at least 2.1 m (about 7 ft) of clearance for farming underneath, and Category II covers interspace systems with farming between the rows.

Height also adds load on carports and overhead systems. Wind pressure increases with height above the ground, and the resulting force acts through a longer lever arm. Both effects raise the moment at the column base and the load on the foundation. On a carport, that moment is one of the main inputs to solar carport frame design.

How Floating Solar Mounting Systems Work

In most floating systems, the modules sit on floats molded from high-density polyethylene (HDPE), either directly or on a metal frame carried by the floats. The floats are joined into one platform, often called a float island, and mooring lines tie it to anchors. The mooring lets the island move within set limits as the water level changes and wind and waves push on it.

Float Platform Designs

The three common designs differ mainly in what carries the modules, the same distinction an IEA PVPS review of floating PV plants uses to group them.

Mooring and Anchoring

Bank anchoring ties the island to anchors on the shore and suits islands close to the bank. Bottom anchoring relies on weights or embedded anchors on the bed, and pile anchoring on piles driven into it. Large plants often combine methods around the perimeter.

Mooring design starts from the range of water levels, because the distance between each anchor and the island changes as the water moves. As the water falls, lines to bottom anchors slacken and the island can drift and rotate. When a slack line snaps taut, it sends a shock load into the connections. As the water rises, the same lines tighten; if they are too short, they pull down on the perimeter floats. Line length and layout, often with elastic mooring elements, keep the island on station across the full range. For sheltered inland and near-shore water, DNV's 2026 standard DNV-ST-E309 sets out how the resulting mooring loads are derived and checked.

Roof vs. Ground vs. Floating Mounting Structures

The three families differ most in where the engineering work and cost concentrate: the existing building on a roof, foundations and earthworks on land, and floats and mooring on water.

When you compare quotes, check the scope of supply first. A racking-only price covers less than one that includes foundations, ballast or mooring and their installation. Either way, a quote is only as reliable as the site data behind it.

Which Materials Are Used in Solar Mounting Structures?

Solar mounting structures are built mostly from aluminum and coated steel and joined with stainless or galvanized steel fasteners. Floating systems add HDPE floats.

Corrosion protection is specified for the site's atmospheric corrosivity category. ISO 9223 classifies exposure from C1 (very low) to CX (extreme), and sites with heavy salt deposition near the shore fall in the upper categories. Under the standard, zinc in a C5 environment corrodes several times faster in its first year than in C3. For buried pile sections, engineers use the soil resistivity and pH from the geotechnical report.

How to Choose a Mounting Structure for Your Site

1. Collect the site data each family depends on. Roofs need a structural assessment and a check of the covering's age and condition. Land needs a topographic survey and a geotechnical investigation. Water needs bathymetry (a survey of the depth and shape of the bed), historical water levels and wind and wave records, plus bed soil data where bottom or pile anchors are planned.
2. Decide the array layout. Tilt and orientation, tracking, clearance for parking or farming, and walkway access on water each rule some subtypes in and others out.
3. Set the design loads under the governing code. Wind, snow and seismic loads for that layout come from the loading code your jurisdiction has adopted, such as ASCE 7 in the United States or the Eurocodes in Europe. The edition in force determines which provisions apply. ASCE 7-22, for instance, introduced wind provisions for fixed-tilt ground-mounted arrays in Section 29.4.5. Floating arrays must also account for wave and current loads.
4. Match materials to exposure and design life. The corrosivity category and design life set the coating, the alloy and the fastener material. Writing them into your specification before bids go out lets every supplier price to the same corrosion requirements.

Plan Your Roof, Ground or Floating Project with Mibet

Mibet designs and manufactures solar mounting structures for roof, ground and floating projects, sized to each site's conditions and loading code. The roof mounting systems include metal roof clamps and L-feet, tile roof hooks and ballasted flat roof systems. Ground mounting systems cover fixed-tilt racking, single-axis trackers, carports and agrivoltaic structures, and floating PV systems combine HDPE floats with aluminum and corrosion-protected steel framing.

Send us the project location, planned capacity, module datasheet, site type and any roof drawings, geotechnical report or water-level records you have. You will receive a preliminary layout, a recommended mounting system and a budget quote.