Dual-Use and Agrivoltaic Module Spec Notes for EPC
Key Takeaway
An agrivoltaic module spec is the mechanical, electrical, and warranty boundary for a module mounted over an active crop or pasture. Clearance, row pitch, design load, cable routing, and a written warranty application have to be set from the farm layout. A rooftop bill of materials copied onto a tall structure is not that spec. This note does not state a crop-yield percentage.
Table of Contents
When a Ground-Mount Spec Is Dropped onto a Crop Row
Dual-use, or agrivoltaic, construction puts photovoltaic modules and an agricultural operation on the same land. The module still has a nameplate, a clamp zone, and a limited warranty. The structure around it does not look like a rooftop or a low ground mount. Posts are taller so a machine or a canopy can pass. Rows are often wider so light and equipment can use the alley. Wind on a tall rack is a structural calculation of its own. Cables that would be a small drip loop on a tracker torque tube can hang in the rear view of a bifacial laminate and in the light the crop was supposed to receive.
The buyer pain is a specification that never names those conditions. Procurement asks for a bifacial TOPCon module because the layout is elevated and someone expects rear-side irradiance. The datasheet that comes back is a standard ground-mount sheet: a design load demonstrated with a clamp the agrivoltaic rack does not use, a cable length that cannot reach the tray, and a warranty whose application list says rooftop and ground mount. The EPC then has to choose between a change order and a mounting method the manual does not allow.
A second confusion is energy language. Bifaciality on a datasheet is a ratio measured in a laboratory. It is not the extra kilowatt-hours the site will produce, and it is not a statement about the crop. Crop performance belongs in the agronomic study. Putting a yield percentage for the plants into the module purchase specification invents a number the module warranty cannot stand behind.
Write the Spec from the Farm Layout Inward
Start with the agricultural plan and the structural concept, then write the module lines those two documents force. The module manufacturer can quote only what you name. If clearance and clamp hardware are still open, the quotation is a catalog module, not an agrivoltaic bill of materials.
Clearance and row pitch
Underside clearance is the free height under the lowest point that a machine, a canopy, or a worker must pass. Take the machine height and the mature canopy from the farm operator. Add the margin that operator requires. On a single-axis tracker, the lowest point is the edge of the module at maximum tilt, not the torque-tube height at noon. A fixed-tilt row uses the lower edge. Do not copy a rooftop standoff into this cell.
Row pitch sets the alley. Ground coverage ratio is the module area divided by the land area of the array block. A lower ratio leaves more direct light for the alley and usually takes more structure and cable per watt of nameplate. The ratio is a project choice agreed with the agricultural plan. This note does not set a universal pitch or a universal coverage ratio. It requires the pitch to be written on the module specification so cable length, rear-side shade, and the energy model describe the same geometry.
Bifacial assumptions
Specify a bifacial construction when the energy model uses rear irradiance, and then keep the two numbers apart. The datasheet bifaciality factor is rear-side maximum power divided by front-side maximum power under standard test conditions, often with a tolerance. Field gain is an output of the model once height, pitch, albedo, and tracking are entered. Vegetation albedo changes with crop, soil, and season. It is not a white roof membrane. Do not reuse a commercial-roof bifacial model on a crop row without changing the albedo and the geometry. Do not add rear-side gain to the warranted front-side nameplate unless the warranty text does that, which standard power warranties do not.
Mechanical load and clamps
An elevated row sees a wind load the structural engineer calculates for that height, exposure, and tilt. The module contributes a design load, stated in pascals, that was demonstrated for a defined clamp position, clamp length, and support span. Your racking must use that position, or the module vendor and the racking vendor must both accept a different position in writing. The test load reported with a qualification file is the load applied during the type test. It is often higher than the design load because the test method applies a factor. Do not treat the larger test-load number as allowable design capacity unless the datasheet says the design load is that number.
Torque and clamp hardware are part of the module spec on this kind of project because the rack is not a standard purlin kit. Name the clamp family the mounting drawings use. If the module manual and the racking manual disagree on zone or torque, stop. The lower of two conflicting numbers is not automatically acceptable. You need a written resolution that both parties will stand behind in a claim.
Cable routing
Rear-side irradiance assumes a view of the ground that the energy model describes. A junction-box lead, a connector pair, or a homerun laid across that view is a shade line the model may not contain. It can also shade the crop alley. Specify the route: tray location, which side of the post, and a drip loop that does not cross the rear glass. Then require the quoted cable length to reach that tray without an inline splice. A short factory lead is not corrected by hanging the cable on a diagonal. Splices add failure points and are allowed only where the installation manual and the local electrical rules allow them.
Warranty application
Ask the warrantor whether this mounting is an intended application. The questions to put in the email are specific: elevated agrivoltaic or dual-use structure, the clearance range, tracker or fixed tilt, the clamp model, and exposure to agricultural spraying and to machinery moving under the array. A sentence that lists rooftop and conventional ground mount does not answer those questions. Chemical exposure, impact, abrasion from vegetation, and installation outside the clamp drawing are typical exclusion themes. Read the exclusion list against this site. If the warrantor confirms coverage, file the confirmation with the purchase order. If the warrantor excludes the use, the module is the wrong product for the layout, even when the electrical ratings fit.
Lines the Module Purchase Must Carry
The table is a specification checklist. The middle column is what the EPC writes. The right column is the source you must not copy from. None of the cells is a universal design value. Where a number is required, it comes from the farm plan, the structural calculation, or the module manual for the model code on the purchase order.
| Spec line | What the EPC records | Do not copy it from |
|---|---|---|
| Underside clearance | Lowest point of the module or tracker sweep, set above machine height, mature canopy, and worker clearance | A rooftop standoff or a noon-only torque-tube height |
| Row pitch and ground coverage ratio | The pitch and the module-area-to-land ratio the agricultural plan accepts | The tightest pitch that maximizes nameplate on the parcel |
| Bifaciality | The datasheet rear-to-front ratio under standard test conditions, with its tolerance | A field-gain percentage or any crop-yield percentage |
| Albedo used in the energy model | A seasonal figure for the crop and soil the farm names | A white commercial-roof albedo |
| Design load and clamp zone | Pascals of design load at the clamp length and position both manuals allow, checked against the elevated-structure calculation | The qualification test load, treated as if it were extra design capacity |
| Cable length and route | Length that reaches the tray on the routing drawing without crossing the rear glass | The shortest standard lead on a catalog datasheet |
| Warranty application | Written confirmation that this height, hardware, and agricultural exposure are included | A generic ground-mount warranty sentence |
Electrical ratings still belong on the same purchase specification, but they do not replace the rows above. Record Voc, Vmp, Isc, Imp, the voltage temperature coefficient, maximum system voltage, and the series fuse rating. String length is set by the coldest-cell open-circuit voltage against the inverter and the module maximum system voltage. A wider agrivoltaic pitch does not, by itself, allow more modules in series. It does lengthen DC homeruns. Voltage drop on those homeruns is a cable calculation, not a module-wattage calculation. If the project is studying a 1,500 V string, that decision stays on the electrical one-line. The module spec either meets that maximum system voltage or it does not.
Name the construction in physical terms: bifacial glass-glass or glass-backsheet, framed or frameless, and the frame material only if a frame is required. Framed versus frameless changes clamps and handling. It is a separate decision from the agrivoltaic geometry. Do not leave it implicit because the rendering shows a frame.
Installation access is part of the mechanical spec. Modules on a tall row are lifted to a height a rooftop crew may not use. The installation manual’s lift points, stack height, and prohibition on walking on the laminate apply, and the method statement should cite them. A module that can only be lifted by a frame is the wrong module if the design is frameless, and the reverse is also true.
What the Module Spec Does Not Decide
- It does not predict crop yield. Plant response to shade, water, and machinery is the agronomic study. Do not write a crop percentage into the module datasheet requirement.
- It does not set a universal clearance or pitch. Those dimensions come from the crop, the machine, and the structure. A module vendor cannot choose them from a wattage class.
- It does not replace the structural engineer. Module design load is a limit the structure must respect. It is not the wind load on the posts.
- It does not convert bifaciality into kilowatt-hours. Use the laboratory ratio as an input. Run the site model with the geometry you will build.
- It does not approve a clamp the manual omits. A custom agrivoltaic rail needs a written clamp acceptance. A catalog load table for a different rail is not that acceptance.
- It does not choose the inverter, the string length, or the frame material. Those are adjacent specifications. The module sheet records the voltage, current, and edge type they must match.
Send the Layout Before You Ask for a Module Code
Share the clearance, the row pitch, the clamp drawing, and the destination country. Weltrus will match a module construction and the warranty application to that layout instead of quoting a generic ground-mount sheet.
Frequently Asked Questions
Is the datasheet bifaciality percentage the same as field bifacial gain?
No. Bifaciality on a datasheet is a laboratory ratio of rear-side power to front-side power under standard test conditions. Field gain depends on height, row pitch, albedo, tilt or tracking, and season. Do not paste the bifaciality percentage into the energy model as if it were site gain.
Where should underside clearance come from?
From the agricultural plan: the tallest machine that must pass, the crop canopy at maturity, and the worker clearance the operator requires. On a tracker, use the lowest point of the sweep, not the height at noon. A rooftop standoff is not this number.
Which mechanical load figure should the EPC match to the elevated structure?
Match the module design load, at the clamp positions the installation manual allows, to the load the structural engineer calculates for that height, tilt, and clamp. The test load on a qualification sheet is the load used in the type test. Do not treat it as extra design capacity unless the datasheet says so.
Why do module cables show up in an agrivoltaic spec?
Leads, drip loops, and homeruns under a bifacial module shade the rear face. On a crop row they can also shade the alley. The routing drawing should keep that cable out of the rear view the energy model assumed was clear, and the quoted cable length has to reach the tray without a diagonal across the glass.
Does a standard ground-mount warranty automatically cover an agrivoltaic mounting?
Only if the warranty text, or a written confirmation from the warrantor, includes that mounting, height, clamp hardware, and the agricultural exposure. Spray chemicals, equipment impact, and a clamp zone the manual does not list are common reasons a claim is refused. Ask before the purchase order. Do not infer coverage from a rooftop or low ground-mount sentence.
