Calculator Inputs
Plotly Graph
This graph scans fixed tilt values from 0° to 60° and estimates a relative annual capture score using monthly noon geometry.
Example Data Table
| Example site | Latitude | Selected tilt | Design day | Hours from noon | Row pitch | Top edge height |
|---|---|---|---|---|---|---|
| Open ground fixed array | 30.00° | 25.90° | Local winter solstice | 1.0 h | 3.28 m | 1.52 m |
Formula Used
1) Fixed tilt estimates
Annual tilt ≈ 0.76 × |latitude| + 3.1
Summer tilt ≈ 0.93 × |latitude| − 21
Winter tilt ≈ 0.875 × |latitude| + 19.2
2) Solar elevation for shading design
sin(α) = sin(φ)sin(δ) + cos(φ)cos(δ)cos(H)
Where
α = solar elevation angle
φ = latitude
δ = declination for the selected design day
H = hour angle = 15° × hours from solar noon
3) Rack geometry
Rise = panel length × sin(tilt)
Ground projection = panel length × cos(tilt)
Shadow length = rise ÷ tan(α)
Row pitch = ground projection + shadow length + extra gap
4) Ground coverage ratio
GCR = ground projection ÷ row pitch
How to Use This Calculator
- Enter site latitude. The tool uses it to estimate seasonal tilt and solar elevation.
- Choose a tilt mode. Annual is balanced, winter is steeper, summer is flatter, and manual accepts your own angle.
- Select the shading design day and the hours away from solar noon that must remain clear.
- Enter panel length, lower edge clearance, and any extra maintenance gap.
- Add row count, module width, and modules per row to estimate land depth and footprint.
- Check the results block above the form for tilt, row pitch, GCR, shadow length, and footprint area.
- Use the Plotly graph to compare your chosen tilt against the best fixed tilt scan.
- Download the results as CSV or PDF for design reviews and field notes.
Frequently Asked Questions
1) What tilt should a ground mount array use?
A common starting point is a tilt near site latitude. Annual designs often use slightly less, winter-focused designs use more, and summer-focused designs use less.
2) Why does winter design need more row spacing?
Winter sun stays lower in the sky, so each row casts a longer shadow. That increases the pitch required to keep the next row clear.
3) Should the array face south or north?
Fixed arrays usually face the equator. In the northern hemisphere that means south, and in the southern hemisphere that means north.
4) What does hours from solar noon mean?
It sets the shading protection window around peak sun. A larger value designs for earlier and later sun, which usually increases spacing.
5) What is ground coverage ratio?
GCR measures how much of the pitch is occupied by module projection. Lower GCR means more spacing, while higher GCR uses land more tightly.
6) Does this replace a structural engineering check?
No. It is a sizing and planning tool. Final post design, footing checks, wind loads, and local code compliance still need project-specific review.
7) Can I use this for sloped ground?
You can use it as a first pass, but sloped sites change clearance, post height, drainage, and shading behavior. Surveyed grades should refine final spacing.
8) Why compare annual, winter, and summer tilts?
The comparison shows tradeoffs. Winter tilt improves low-sun performance, summer tilt reduces height and spacing, and annual tilt balances yearly energy capture.