Agrivoltaic Mounting Structures: Elevated, Vertical and Inter-Row

How Agrivoltaic Structures Are Classified

The main classification question is whether farming happens underneath the modules or between the rows. Germany's DIN SPEC 91434 uses that split. Category I covers elevated systems with enough clear height for crops to grow under the array, and Category II covers systems close to the ground, with cultivation mainly between the rows.

Italy's 2022 agrivoltaic guidelines keep that split but name three types. Raised systems allow farming under and between the modules. Inter-row systems confine it to the gaps between rows, and vertical systems stand the modules upright between crop strips. The German pre-standard places vertical arrays in Category II. Even so, their fence-like shape and east-west orientation change how they carry wind load, what foundations they need and how they generate power.

Compared with a standard ground mount on agricultural land, an agrivoltaic structure starts from a different design brief. A conventional array is laid out for energy yield and cost per watt, with modules close to the ground and rows as tight as shading allows. Here, the farm sets the clearance, column grid and row spacing first: the height of the tallest machine, the width of a spraying pass, the light a crop needs and the height grazing animals can reach. Meeting those dimensions usually means more material per kilowatt and larger foundation loads than a ground mount of the same capacity. Conventional ground mounts, along with roof and floating systems, are compared in a separate guide to the types of solar mounting structures.

Elevated (Overhead) Structures

An elevated agrivoltaic structure works like an open canopy over the field. Tall columns carry main beams that span the working lanes, and the modules sit on purlins or rails high enough for a tractor, a picking platform or a sprayer to pass underneath. The load path runs from the modules down through four groups of members:

• Purlins or module rails carry the modules and fix their spacing.
• Main beams span between columns and define the width of the clear working lanes. Their slope usually sets the module tilt.
• Columns carry vertical loads into the foundations and resist the bending that wind produces on a tall frame.
• Bracing ties the frame together to limit sway and racking in a crosswind.

Besides clearance height, the column grid and light transmission shape the rest of the layout. In an orchard, for example, column lines can follow every second or third tree row and stay out of the drive alleys. More light on the crop always costs some capacity per hectare, whether it comes from wider gaps between modules, a lower ground coverage ratio (module area relative to land area) or semi-transparent modules.

Many early trade-offs come down to the column grid. Longer spans leave fewer columns in the field and make harvest runs simpler, but they need deeper or stiffer beams to limit deflection and keep the modules aligned. Shorter spans allow lighter members at the price of more foundations and obstacles. Aluminum is roughly one-third as stiff as steel, so a long aluminum span needs deeper sections. In return, an aluminum frame is lighter and protected by its natural oxide layer.

The usual candidates for an elevated frame are orchards, vineyards, berry crops, vegetables and other crops that benefit from partial shade or hail cover. If your orchard needs hail nets or rain covers, the PV frame can carry them as well. Their wind and hail loads go into the structural design from the start. Installation, cleaning and module replacement all happen at height. The layout has to leave room for lift access and keep cable trays above machine height.

Vertical Bifacial Structures

In a vertical bifacial array, the modules stand upright, typically in rows running north-south so that one face points east and the other west. The arrangement only works with bifacial modules, which produce power from both faces. The east face takes direct sun in the morning and the west face in the afternoon, but around noon sunlight runs almost parallel to both faces and leaves them with mostly diffuse and ground-reflected light. On clear days, the daily output curve shows a morning peak and a late-afternoon peak, with a dip around midday. The yield gap between vertical and tilted arrays narrows at high latitudes, where the sun stays low for much of the year.

A single line of posts carries horizontal rails, and the modules mount vertically on those rails. Arable farming, haymaking and grazing fit this layout well, especially on farms that run wide equipment along long, uninterrupted lanes.

Setting the lower module edge above mowing height and planting crops back from the row keeps the bottom cells clear. If the edge sits too low, a cereal crop or weeds can grow tall enough to shade the bottom row of cells late in the season. The shaded cells can switch on the bypass diode for their substring, and that substring drops out until the shade clears. With standard modules in portrait, the bottom row holds cells from every substring. A full-cell module can then lose most of its output, while a half-cut module generally loses less.

Row spacing decides how much light the crop gets. A University of Turku analysis modeled vertical rows in Finland at about 60°N. With rows 10 m (about 33 ft) apart, about 90% of the field stayed open for cultivation. Crops between the rows received roughly 80% of the irradiance of an unshaded reference.

Inter-Row Tilted and Tracking Structures

Inter-row agrivoltaic structures keep the tilted rows of a standard ground mount and change mainly their height and spacing. Cultivation needs wider gaps between rows, and grazing calls for a lower edge high enough for sheep to move beneath the modules.

Two forms are in common use:

• Raised fixed-tilt structures. Rows face the equator at a fixed angle. On two-post frames, raising the lower edge lengthens both front and rear columns, and the taller rear column usually needs diagonal bracing to keep the frame stiff. A steeper tilt lifts the upper edge further and lengthens the lever arm for wind loads. Designers treat tilt, lower-edge height and bracing as one decision.
• Single-axis trackers. Rows run north-south and track the sun from east to west, as a conventional single-axis tracker does, but stand higher and farther apart. Depending on its rotation range and controls, a tracker can hold the modules at a steep angle during field work to widen the clear lane for machinery. In that position, the lower edge drops closer to the ground.

Most structural components, from posts and rails to clamps and fasteners, carry over from standard fixed-tilt and tracker designs. Longer columns and extra bracing raise the structural cost. Wider spacing adds cable length and land area per megawatt.

Elevated vs. Vertical vs. Inter-Row Structures

Elevated structures keep almost the whole field workable under the modules and use the most material. Vertical rows give up only a narrow strip each and leave wide lanes for large machinery, while inter-row structures stay closest to standard ground-mount practice. None of the three leads on every measure, and your farming system and project location decide which trade-off pays off.

The table below compares the three agrivoltaic mounting structures on farm access, crop light and structural demands.

Material per kilowatt is a good first guide to the structure budget. It rises with clearance, span and wind exposure, and the same factors drive foundation count and erection time. Location can also reverse the economics, as a European modeling study of crop rotations in four countries showed. Elevated systems were more profitable than vertical ones in Germany and Italy, where their higher electricity output covered the added installation cost. In Sweden and Denmark, vertical systems came out ahead. Across all the agrivoltaic systems it modeled, single-axis trackers were the most profitable.

Setting Clearance Height and Row Spacing

Clearance height starts with whatever has to fit under the frame:

• the full working height of each machine and attachment, including the cab, booms, exhaust stack and GPS antenna, plus a margin
• the lowest beam, knee brace or cable tray along each working route, measured from the highest ground beneath it
• the livestock species, with cattle needing far more headroom than sheep
• the mature height of the crop, including trellises, posts and hail nets
• a tracker's full rotation range, since the lower edge drops as the rows tilt

Once you know those dimensions, the project also has to meet any agrivoltaic or dual-use rule that applies. Each rule sets its own minimum and measurement point, and their legal weight ranges from technical guidance to binding law.

Row spacing is set the same way, by what has to fit between the rows. For vertical and inter-row structures, the clear lane between module edges allows for the width of your widest implement plus a lateral safety margin. The row pitch of tilted rows is that lane plus the strip of ground under the modules. Each lane also needs headlands at both ends wide enough for the machine to turn. The light check that follows works best season by season. An annual average shading figure can hide a shortfall during the growth stage that sets yield.

Loads and Foundations on Working Farmland

For most agrivoltaic structures, wind governs the design, and snow can take over in heavy-snow regions.

Wind and Snow Loads

Wind acts on an elevated array high above the column bases. The overturning moment at each base grows in proportion to that height, and wind speed rises with height as well.

For an open elevated array, engineers often derive the wind force from the canopy or free-roof provisions in codes such as ASCE 7 in the United States and EN 1991-1-4 in Europe. Arrays outside those provisions need site-specific analysis. On vertical rows, each post works as a cantilever from the ground, and wind can load the full module face from either side.

Snow that sheds off modules several meters up lands in a concentrated band below the low edge. Over trellised vines or a lane used for winter pruning, the band can bend trellis wires and block access until it melts. Tilt direction and lane layout decide where that band falls.

Foundations That Leave the Soil Workable

Driven piles and ground screws are the usual foundations for agrivoltaic structures. Both need little or no concrete and can be removed at decommissioning. As on any ground mount, engineers set the embedment depth from the site loads and the geotechnical investigation, then confirm it with on-site pull-out and lateral load tests.

On cultivated land, regular tillage loosens the topsoil, which would otherwise give a pile much of its lateral resistance. The pile has to mobilize that resistance in the undisturbed soil below instead. Load tests are most representative in tilled ground. Pile heads and baseplates near working lanes need to stay clear of turning machinery. Buried cables run below the depth plows and subsoilers reach, or along strips kept out of cultivation.

Elevated and Inter-Row Structures from Mibet

Mibet manufactures agrivoltaic mounting systems in two forms: elevated long-span aluminum structures that keep machinery lanes open beneath the modules, and raised fixed-tilt structures for inter-row cultivation and grazing. Each design begins with the crop or livestock plan, implement dimensions, site loads and local clearance and coverage rules. In Japan, Mibet has supplied mounting systems for agrivoltaic sites, including a 4 MW vineyard installation in Fukushima Prefecture with modules about 2.5 m (8 ft) above ground.

Share your site location, target capacity, planned crops or livestock and machinery dimensions. We will prepare a preliminary layout showing clearance and row spacing, recommend a mounting structure and provide a quotation.