Why This Is Difficult
Shading losses are frequently mis-estimated, and the errors come from the model rather than from the physics.
- Annual shading percentages hide the fact that losses are concentrated in the morning, evening and winter months, where energy value may be higher or lower than average
- Partial shading of a module string produces losses larger than the shaded area alone, because the string current is limited by the shaded cell
- Fixed-tilt and tracker require different models, since backtracking changes when and whether a row shades its neighbour
- Winter shading behaves differently from summer shading at the same site, and a model run on a single representative day will miss it
- Row pitch interacts with the terrain, because a slope changes the effective vertical separation between adjacent rows
- The non-linear cost of tightening rows means that small reductions in pitch produce disproportionately large losses past a certain point
Engineering Requirements
These are the inputs an inter-row shading analysis requires.
- Hourly irradiance and sun position data for the site, covering a full year rather than representative days
- Module electrical configuration, including string length and the bypass diode arrangement, since shading losses depend on it
- Structure type and geometry: fixed tilt angle or tracker rotation range, module dimensions and mounting height above grade
- Site topography, because slope changes the effective row-to-row separation and the shading geometry
- Ground coverage ratio target or land constraint that sets the allowable pitch range
- Energy price structure, so that shading losses are valued by the hour in which they occur
Selection guidance: model the module electrical configuration, not just the geometric shadow. The shadow is a geometry problem, but the loss is an electrical one, and it is usually larger.
How We Solve It
- Hourly, full-year shading modelling that accounts for the electrical response of the module string rather than only the geometric shadow
- Structure-specific models: backtracking for trackers, tilt-dependent geometry for fixed-tilt arrays
- Terrain-adjusted geometry, so row pitch is evaluated against the actual ground profile rather than a flat plane
- Loss valued by time of day and season, so the row pitch reflects the value of the energy being lost
- Row pitch curve presented across a range, showing where tightening produces disproportionate loss and where widening stops earning
- Winter and summer cases reported separately, since the governing case is often the winter one at high latitude
Beyond the Structure
- Row pitch recommendation with the module and tracker configuration stated, so the layout can be checked if either changes
- Layout review against cadastral boundaries, since the theoretical optimum pitch may not fit the available land parcel
Reference Benchmarks
Benchmarks below are publicly documented industry reference projects of comparable type and scale, cited to illustrate engineering practice. They are not our delivery record.
- A 180 MW project in Germany where full-year modelling showed winter row shading governing the pitch rather than the summer case.
- A 250 MW tracker project in the United States where backtracking removed most low-angle shading and allowed a tighter pitch than the fixed-tilt model had suggested.
- A 120 MW site in Italy on sloping ground where terrain-adjusted row separation changed the recommended pitch on part of the array.
Standards and Compliance
- ASCE 7 / EN 1991 / AS-NZS 1170 wind load cases with site-specific terrain categories
- IEC 62727 tracker structural requirements where tracking structures are in scope
- EN 1090-2 or AISC 360 fabrication and execution class documentation
- ISO 1461 hot-dip galvanizing, ISO 9223 corrosivity classification driving zinc mass
- ISO 9001:2015 quality system, ISO 14001 environmental management on request
- Third-party aeroelastic wind tunnel study available for large-format modules
Quality Assurance
Quality control is checkpoint-based: material intake verification, in-process weld and hole-position inspection, coating thickness sampling and pre-shipment container review. Each checkpoint produces a document your quality team can file, and pre-shipment inspection is open to your inspector or a third party.
Documentation You Receive
The paper trail matters as much as the steel. With each delivery you receive mill test certificates traceable to heat numbers; galvanizing records per batch against ISO 1461 or your specified standard; dimensional inspection reports from pre-assembly jigs; bolt and hardware lot traceability; as-built drawings where site adaptations were made; and a warranty document naming covered load cases, service design life and claim procedures. Everything is indexed, so your asset register does not depend on one engineer’s memory.
Service Life and Maintenance Planning
Replacement planning is part of the design: clamp geometry allows individual module swap without cutting rails, pile heads accept re-levelling after settlement, and spare-part packages are sized to your environment class and capacity. That keeps mid-life rework fast, predictable and independent of the original supplier’s product catalogue.
Cost and Commercial Considerations
- Row pitch is one of the largest single levers on land area and therefore on land cost, roads, cabling and fencing
- Tight pitch reduces land and balance-of-system cost but increases shading losses, with the loss curve becoming steep past a certain point
- Module and string configuration affects the loss significantly, so a shading study run without the electrical model understates the penalty
- Tracker backtracking reduces low-angle losses and therefore supports tighter pitch, which is a cost benefit that a fixed-tilt model cannot show
- The study cost is small against the land area it determines, and it should be completed before the layout is frozen
Frequently Asked Questions
How much energy does inter-row shading actually cost?
Why is the geometric shadow not enough?
Does backtracking remove the need for generous pitch?
How does slope affect row pitch?
What pitch should we start with?
Related Guides and Application Pages
Continue with the pages closest to your project type.
What We Need to Quote
- Site coordinates and hourly irradiance data, or a location from which it can be derived
- Module and string configuration, including bypass diode arrangement
- Structure type, tilt or rotation range, and module mounting height
- Topographic survey of the developable area
Talk to a Structure Engineer
Send the site location, module configuration and structure type, and we will return a row pitch curve showing the shading loss against the land saved, with the recommended pitch stated.
