East-West vs Single-Axis Tracker Density

The Challenge

An 85 MWp project on a constrained industrial brownfield had a hard boundary: 98 hectares of usable area with no expansion option. The developer’s target was maximum installed capacity within the fixed footprint. Single-axis trackers were the default assumption, but the site’s rectangular shape and internal exclusion zones (access roads, drainage corridors, an existing substation) created irregular blocks that reduced tracker row efficiency.

The engineering team needed to determine whether East-West dome rack configurations could deliver higher energy density on the same footprint, and at what cost trade-off.

Site Conditions

PVX.Cad mapped the terrain and defined exclusion zones:

• Total site area: 98 ha
• Usable area after exclusions: 81.3 ha
• Average slope: 4.2% (relatively flat, minor grading needed)
• Exclusion zones: 4 internal access roads, 2 drainage corridors, substation setback
• Soil: Uniform compacted fill (brownfield), no rock classification needed

The flat terrain meant grading was not a primary cost driver. The constraint was purely spatial: maximum watts per available hectare.

Two Configurations Compared

Configuration A: Single-Axis Trackers (1P, 2x28 tables)

Standard single-axis tracker layout with north-south row orientation, 2x28 module tables, and GCR optimized for the site latitude.

• Installed capacity: 79.2 MWp
• Modules: 143,640
• GCR: 0.38
• Row pitch: 6.8 m
• Specific yield: 1,680 kWh/kWp
• Annual energy: 133.1 GWh
• Capacity density: 0.974 MWp/ha (usable area)

Tracker rows required wider pitch for backtracking clearance, and the irregular block shapes left dead zones at block edges where short rows were uneconomical.

Configuration B: East-West Dome Racks (15 degree tilt)

PVX.Cad generated East-West dome configurations with 15 degree tilt angle, paired modules facing east and west. The narrower profile allowed tighter row spacing.

• Installed capacity: 96.4 MWp
• Modules: 174,960
• GCR: 0.62
• Row pitch: 2.9 m
• Specific yield: 1,410 kWh/kWp
• Annual energy: 135.9 GWh
• Capacity density: 1.186 MWp/ha (usable area)

E-W racks filled irregular block shapes more efficiently (shorter rows are viable in E-W) and the narrower pitch recovered area lost to tracker backtracking zones.

Full Comparison

Energy vs Capacity Trade-off

E-W racks produced lower specific yield (1,410 vs 1,680 kWh/kWp) due to the non-tracking orientation. But the 22% higher installed capacity compensated: total annual energy was 2.8 GWh higher with E-W despite the lower per-watt yield.

The energy production curve also differed. E-W racks generated a flatter daily profile with earlier morning and later afternoon output, which can be advantageous for grid feed-in tariff structures that penalize midday peaks.

Civil Cost Comparison

The flat site meant grading costs were minimal for both configurations. The cost difference showed up in structural and mounting costs:

Key Findings

1. 22% higher installed capacity on the same footprint (96.4 vs 79.2 MWp).
2. 2.8 GWh more annual energy despite 16% lower specific yield.
3. 24% lower per-watt civil costs ($0.093 vs $0.122/Wp).
4. E-W racks filled irregular blocks more efficiently, recovering dead zones that tracker rows could not use.
5. Flatter daily production curve with E-W, potentially better for grid tariff structures.
6. Trade-off is real: if land is available and specific yield matters more than density, trackers remain the better choice. E-W wins when land is the binding constraint.
7. Both configurations were generated, compared, and exported in a single AutoCAD session using PVX.Cad.

Designed with PVX.Cad and PVX.View.