Solar Azimuth Optimization Calculator

Inputs

Latitude (°)

North positive, south negative. Range -90 to 90.

Roof bearing type

Choose the compass reference for your roof bearing.

Roof azimuth (°)

0=N, 90=E, 180=S, 270=W.

Magnetic declination (°)

East positive, west negative. Use 0 if unknown.

Allowed azimuth deviation (±°)

Set 0 if panels must match roof direction.

Panel tilt (°)

Angle from horizontal. 0 = flat, 90 = vertical.

Optimization preference

Shifts target azimuth slightly for practical goals.

Shading loss (%)

Quick estimate of annual shading impact.

Tip: If your roof bearing is magnetic, enter declination to convert results correctly.

Example Data Table

Latitude (°)	Roof Azimuth (°)	Allowed (±°)	Tilt (°)	Preference	Shading (%)	Recommended True (°)
30.0	190	30	25	Balanced	5	180–195
40.7	160	20	35	Afternoon	8	170–180
-33.9	10	25	25	Morning	3	0–25
52.0	210	15	40	Winter	12	195–210

Example outputs show typical ranges when roof constraints apply.

Formula Used

Azimuth convention: 0° North, 90° East, 180° South, 270° West.
Ideal equator-facing azimuth: 180° for Northern hemisphere, 0° for Southern hemisphere.
Preference bias: a small offset (≈ 5–15°) toward east or west to favor morning or afternoon production.
Roof constraint: recommended azimuth is clamped within roof ± allowed using shortest angular distance.
Tilt estimate: a rough optimal tilt is |latitude| (capped near 60° for practicality).
Relative yield estimate (planning-grade):
Yield% ≈ 100 × cos(|Δaz|) × cos(|Δtilt|) × (1 − shading/100)
where Δaz is the deviation from ideal equator-facing azimuth, and Δtilt is tilt error from the tilt estimate.
Magnetic conversion: if declination is east-positive,
True = Magnetic + Declination and Magnetic = True − Declination.

For high-accuracy performance modeling, use a dedicated PV simulation tool and verified site measurements.

How to Use This Calculator

Enter the site latitude to set the hemisphere and equator-facing ideal direction.
Select whether your roof bearing is true or magnetic.
Enter the roof azimuth and the allowed deviation for mounting flexibility.
If you use a compass, add magnetic declination for correct conversion.
Choose your preference: balanced, morning, afternoon, winter, or summer.
Estimate shading loss, then click Calculate to see results.
Use the download buttons to export a quick project summary.

Construction tip: confirm roof framing, wind loads, and access clearances before finalizing orientation.

Professional Notes

Article (330 words)

Azimuth Decisions for Roof-Mounted Arrays

Azimuth sets the compass direction that modules face, shaping annual production and time-of-day output. In construction planning, the roof’s geometry, parapet setbacks, and racking limits often matter more than theoretical optimum. This calculator starts from an equator-facing reference and then applies practical constraints so crews can install within realistic tolerances. Use the deviation value to check whether standoff systems or adjustable mounts are required. When the roof has multiple planes, run each plane separately and compare deviations. Aligning azimuth choices with fall-protection routes and maintenance access helps avoid future shading from added equipment. This supports safer sequencing during installation.

True Versus Magnetic Bearings on Site

Field measurements frequently come from compasses or phone sensors, which report magnetic bearings. For layout accuracy, convert to true bearing using local magnetic declination, with east-positive values increasing true azimuth. Recording the bearing type, declination, and final recommended magnetic azimuth reduces rework when survey notes and drawings use different references.

Balancing Energy Profiles and Demand

Many projects optimize more than yearly kilowatt-hours. A slight east bias can lift morning output for early occupancy, while a west bias can support late-day loads. The preference setting applies a small offset, then clamps the recommendation to the allowed deviation around the roof direction. This preserves constructability while still supporting operational goals.

Shading, Tilt, and Constructability Impacts

Shading losses from adjacent buildings, rooftop equipment, and guardrails can dominate azimuth gains. The calculator applies a shading factor to estimate relative yield and highlights when improvements are limited by obstructions. Tilt is compared with a latitude-based guideline to flag large deviations that may indicate drainage constraints, wind loading concerns, or structural limitations.

Documentation and Handover for Teams

For coordination, capture the recommended true and magnetic azimuth, roof azimuth used, deviation angle, and assumptions on shading and tilt. Exporting a concise CSV or PDF supports submittals, inspection checklists, and commissioning records. Treat results as planning-grade; confirm final angles with verified survey control and project specifications before procurement.

FAQs

What azimuth should I target in the Northern hemisphere?

Start near true south (about 180°) for maximum annual energy. Then apply roof constraints, safety clearances, and your time-of-day preference to choose a buildable final orientation.

How do I determine magnetic declination for my site?

Use a current local declination value from surveying references, aviation charts, or geomagnetic tools. Enter east as positive and west as negative so the calculator converts between magnetic and true bearings correctly.

Why does the recommendation stay close to the roof direction?

Roof-mounted systems often have limited rotation due to anchors, rail alignment, wind loads, and drainage paths. Clamping within an allowed deviation helps keep the output practical for construction and inspection.

Is the relative yield value an exact energy prediction?

No. It is a quick, planning-grade indicator that combines azimuth mismatch, tilt mismatch, and an assumed shading percentage. Use a full solar model and site measurements for final production estimates.

How should I estimate shading loss for early planning?

Walk the roof, note nearby walls and equipment, and consider seasonal sun paths. If uncertain, choose a conservative loss percentage and refine it after a detailed shade study or drone survey.

What if my roof faces east or west instead of south?

Run the calculator with your actual roof azimuth and realistic deviation limits. Consider splitting arrays across planes, using multiple orientations, or adjusting preference to match building load profiles and utility tariff windows.