Solar row spacing & GCR calculator

Estimate solar-array clear row gap, front-to-front pitch, projected coverage, collector-width GCR and field depth from latitude, tilt and a chosen solar time using a simplified side-section model.

Project inputs

Defaults are examples, not recommendations. Replace them with traceable project assumptions.

North positive; south negative. Limited to ±66°.
Use the local winter design date for the hemisphere.
Solar time, not necessarily clock time.
Angle above horizontal.
Full table length measured along the tilted plane.
Used only to estimate total field depth.

Screening result

Updated from the inputs at left.

Preliminary decision support only. Confirm inputs, governing standards and final conclusions with the responsible qualified professional before design, procurement or construction.

Method and assumptions

The calculator determines solar altitude from latitude, day of year and local solar time, then applies simple section geometry. Array rise is L × sin(tilt); horizontal projection is L × cos(tilt); clear gap is rise ÷ tan(solar altitude).

  • Use solar time rather than civil clock time.
  • The result treats the site as level and rows as parallel.
  • Check the result in a terrain-aware shading model before design.

Row spacing, pitch and two different coverage ratios

Row spacing is the clear horizontal gap between array rows. Pitch includes that gap plus the horizontal projection of the tilted collector. Rail spacing is a different question: use the module and mounting-system documents for support positions.

Side view of two tilted solar rowsCollector slope length L projects horizontally by L cosine tilt. Front-to-front pitch equals that projection plus the clear gap. Diagram is schematic, not to scale.Slope length LProjectionClear gapPitchRise
Schematic side section; row azimuth, terrain and three-dimensional shading are not modelled.

Reproducible example: 35° N, December 21 at solar noon

With a 4.6 m collector slope length, 25° tilt and 20 rows, the tool gives solar altitude 31.55°, rise 1.944 m and horizontal projection 4.169 m. The section-model gap is 1.944 ÷ tan(31.55°) = 3.166 m; pitch is 7.335 m, and total field depth is 143.5 m.

Neither value includes site roads or boundary setbacks. Software definitions differ: PVsyst explains its GCR conventions, including active area and collector-width distinctions. Check the receiving model before transferring a number.

Load this spacing example

Choose a time, then check the model boundary

Solar time is not clock time; NOAA defines solar noon by the local meridian. A southern-hemisphere winter example uses June rather than December. This calculator uses an approximate solar-altitude model and a two-dimensional section: it does not include solar azimuth, terrain, diffuse light or annual energy losses. Its gap is not a site-wide no-shading guarantee. Use a site-specific shading model for design.