Pros and Cons of Ground-Mount Solar Racking Systems

Advantages of Ground-Mount Solar Racking Systems

Most ground-mount advantages come from the freedom to place and shape the array. Roof geometry no longer fixes the available area, slope, or orientation, though the site brings its own limits.

More Freedom in Array Layout and Orientation

A fixed-tilt ground mount gives engineers more control over module orientation, tilt angle, row spacing, ground clearance, and table geometry, meaning one group of modules carried on a shared set of posts and beams.

Orientation and tilt follow the site's solar resource, seasonal production targets, shading conditions, and available land.

Row spacing belongs to the same decision. Wider spacing reduces inter-row shading and opens up working room, and the array then covers more land. A steeper tilt raises the vertical height of each row and lengthens the shadow it casts, so the row pitch has to grow to hold the same shading loss. Designers track that relationship through the ground coverage ratio (GCR).

GCR is a layout ratio rather than a design limit. Tilt, row pitch, and land use move together, so a layout cannot be optimized for energy yield and land efficiency separately. The workable range for any one project comes from its own shading study and land constraints.

Ground clearance affects both layout and structure. More clearance gives the array room for vegetation, uneven ground, snow accumulation, and maintenance work. Raising the array also lengthens the exposed section of each post, so the same wind pressure acts through a longer lever arm and produces a larger bending moment at the foundation. The post section, the connections, and the embedment depth all grow with it.

Easier Access for Inspection and Maintenance

Ground-level arrays are easier to reach for visual inspection, module replacement, cleaning, wiring checks, and other routine work. Large projects also lay out access lanes for personnel and equipment from the start.

Maintenance needs do not disappear. They move to ground level, where vegetation, erosion, drainage, access routes, and the surface beneath the modules become part of normal site management. Research funded by the DOE Solar Energy Technologies Office through the PV-SMaRT project produced runoff estimation tools and stormwater best practices written specifically for ground-mounted PV sites.

Array Size and Future Expansion on Ground-Mounted Sites

Available land can carry an array well beyond the capacity of a single building roof. Developers have room to set table count, row count, service access, and equipment locations around the target project capacity, while rooftop capacity stops at the usable roof area.

Expansion gets easier when suitable land sits next to the original array. Reserved land only supports that expansion if the first phase also leaves room in the conduit routes, the transformer pad layout, and the interconnection capacity.

The module footprint is only part of the land requirement.

Disadvantages of Ground-Mount Solar Racking Systems

Foundations carry dead load, wind, and snow into the ground. Cable routes cross the site, and terrain decides how closely the planned tables can follow the layout drawing. These line items often explain more about project cost than the racking price alone.

Ground-Mount Arrays Require Usable Land

A ground-mounted array needs space for the modules, and it needs room for everything else on the site. Before the parcel can be sized, the usable area has to absorb:

• Inter-row spacing
• Inspection and maintenance access
• Inverter and transformer locations
• Cable routes
• Drainage provisions
• Internal roads and equipment access
• Required site or regulatory setbacks

Land value carries weight too. Industrial property, agricultural land, constrained commercial sites, and parcels held for future development all put a real cost on the area an array occupies.

Foundations Add Ground and Civil Engineering Work

A ground mount needs a foundation that transfers dead load, wind, and snow into the soil, including the uplift and overturning forces wind produces on a tilted array.

Common foundation types include driven steel piles, ground screws, helical piles, and concrete foundations. Ballasted foundations come in where penetration is restricted, such as capped landfills or sites with shallow bedrock.

Selection works through the same order on every project:

1. Ground conditions. Soil profile, bearing capacity, groundwater, and whether the site can be penetrated at all.
2. Structural loads. Compression, uplift, and lateral force arriving at the top of the foundation.
3. Mounting structure. The racking geometry and the interface it presents at the post base.
4. Installation method. The equipment that can work on the site and how it reaches each row.
5. Local project requirements. Permitting conditions, ground-disturbance limits, and site-specific constraints.

A foundation change reaches well beyond the component under the post. It can change:

• Installation equipment
• Excavation or concrete work
• Steel or concrete quantities
• The racking-to-foundation interface detail
• Construction sequence and installation time

The foundation and the soil therefore belong in the cost discussion from the start. A racking quotation has limited meaning until you know how the structure will be supported at the site.

Site Preparation and Electrical Routing Expand the Project Scope

Some ground-mounted projects need grading, vegetation work, trenching, access routes, or drainage improvements before the first table goes up.

The amount varies by site. Relatively even ground needs little earthwork. Irregular terrain may call for table-height adjustments, foundation changes, localized grading, or a different construction approach. Grading quantities feed straight into both the construction budget and the schedule.

Electrical work also extends across the site. DC and AC circuits run between array blocks, inverters, transformers, and the point of interconnection. The project design sets the routing method, whether direct burial, conduit, or above-grade cable management. Trenching, conduit, backfill, and equipment pads sit inside the same construction scope as the racking itself.

Ground-Mount vs. Roof-Mount Solar Racking

Ground mounting and roof mounting support the same PV modules. Ground arrays rely on foundations and soil conditions. Rooftop arrays rely on the existing building and roof assembly.

Where the structure lands, and what caps the array size, account for most of the differences below.

Ground mounting shifts the structural interface from the roof to the foundation and soil. Columns, beams, connections, and foundations still carry the design loads along one continuous path, and the lowest-capacity element in that path sets the limit for the whole structure.

Difficult soil or terrain adds work to a ground-mounted project. A roof with structural, waterproofing, access, or attachment constraints adds work on the rooftop side. Project scope gives a more useful comparison than mounting location alone.

How Site Conditions Change the Ground-Mount Trade-Offs

Terrain sets the working surface, the soil decides the foundation, and wind and snow set most of the structural demand. These inputs also pull on each other, so a tilt change made for energy production or snow behavior lands on the wind loading as well.

Terrain and Drainage Affect Layout and Site Work

Slope and surface variation drive table elevations, post exposure, construction access, and the earthwork quantity across the array.

No single maximum slope applies to every ground mount. The workable range comes from table geometry, foundation type, the post-height adjustment built into the racking, and the working slope of the piling equipment, which on many sites turns out to be the binding constraint.

Drainage gets settled during the layout work. Rain sheets off the modules and concentrates along the low edge of each row, in a strip the industry calls the dripline, and grading or vegetation decides where that water goes next. Left alone, concentrated flow moves soil off the site and cuts channels between rows.

Erosion also reaches the structure itself. DOE flood-resilience guidance for PV systems notes that downhill flow can carry enough velocity to wash out soil and undermine foundation piles and equipment pads, with arrays sitting at the base of a slope among the most exposed.

What the Soil Data Decides About the Foundation

The soil resists the compression, lateral load, and uplift transferred down through the racking. Its properties set foundation dimensions, embedment depth, installation method, and sometimes the foundation type itself.

Capacity comes from three places.

Each contribution shifts with the ground, so the same pile section develops different capacity in dense soil, loose fill, weathered rock, and layered profiles.

Wind, Snow, and Exposure Define Structural Demand

Wind and snow arrive at the modules and leave through the foundations, and every member between them carries the load.

1. PV modules
2. Beams
3. Posts
4. Foundations
5. Soil

A steeper array sheds snow more readily. It also presents a larger face to the wind and changes the net pressure coefficient the structure is designed against, so one tilt decision moves energy yield, snow behavior, structural demand, and steel quantity together.

Snow that sheds off a tilted array piles at the low edge of each row. When the drift reaches the bottom of the module frame, the row carries an uneven load and the lowest cell string sits in shadow, which can put the bypass diode into conduction. In snow country, the expected drift height sets the ground clearance.

Ground clearance feeds back into the wind loads. Velocity pressure rises with height above ground, so the same design wind speed produces higher pressure on a taller table.

For U.S. projects, ASCE/SEI 7-22 Section 29.4.5 covers wind loads on ground-mounted fixed-tilt PV systems, which earlier editions did not address directly. The tabulated method carries stated geometric limits.

Step outside those limits and the tabulated coefficients stop applying. The design then moves to wind tunnel data under ASCE/SEI 49-21. Projects elsewhere work to their applicable national codes, such as EN 1991-1-4 in Europe together with the National Annex for the country in question.

Two answers therefore matter early on. The project team needs to know which structural code governs the site, and whether the planned array geometry sits inside that code method's applicability limits. Those answers decide whether the design runs on tabulated coefficients or on wind tunnel data, and that difference shows up in both the engineering schedule and the fee.

When Is Ground-Mount Solar Racking the Better Choice?

Ground mounting fits projects that need layout freedom and have enough suitable land for the foundations, access, and civil work that come with it.

Commercial, industrial, and larger PV projects meet those conditions often, usually when the available roof:

• Is too small for the target capacity
• Faces the wrong way
• Carries other equipment
• Is off limits for PV

Projects built around a specific fixed tilt, or holding space for a later phase, fall into the same group.

Ground-Mount Solar Racking Design for Your Project

Where a ground-mount solar racking system starts depends on how far the project design has already gone.

When the racking still needs engineering, the Mibet team works from the module, the site plan, the structural load criteria, and whatever foundation and installation information exists, then develops the array layout and racking configuration around those conditions.

When the design is already complete, Mibet manufactures and supplies the racking to the approved drawings and specifications.