Azimuth

Quick Facts

What is Azimuth?

Azimuth is the compass orientation of a PV array, measured clockwise from true north. It determines when during the day the array receives peak irradiance.

Common azimuths (northern hemisphere)

• 180° (due south): Maximum annual energy.
• 135° (SE) / 225° (SW): ~96% of due-south production.
• 90° (E) / 270° (W): ~80-85% of due-south production.
• 0° (N): ~50% or less.

NEM 3.0 Implications

In California under NBT (NEM 3.0):

• Midday export rates: $0.02-0.08/kWh.
• Evening (4-9 PM) export rates: $0.20-0.80/kWh.

A west-facing module generates more in the high-priced evening window, potentially producing 10-20% higher revenue per kWh despite ~10% lower annual production. Mixed east-west designs balance morning and evening production.

Engineering Deep Dive

POA reduction by azimuth deviation

For a 30° tilt angle at 30°N latitude:

True vs. magnetic north

Always use true north. Magnetic declination varies by location and time (±20° in some areas). Use a GPS-based true-north tool or solar pathfinder.

Multiple orientations

For rooftops with two azimuths (east + west, common on gable roofs):

• Use 2+ MPPT inverter.
• Each MPPT covers one orientation.
• Microinverters or a DC optimizer per module are an alternative that avoids the mismatch loss of mixing azimuths on one MPPT.

Permitting Implications

Azimuth must be shown on the site plan and the SLD, and PE-stamped designs include azimuth verification per orientation. Our Solar Permit Design team cross-checks the stated azimuth against the site survey before drawings go to the AHJ.

Best Practices

• Use a smartphone compass (with magnetic-to-true correction) or GPS for site survey, confirmed on-site through our Site Survey & Land Feasibility service.
• For mixed orientations, allocate separate MPPTs or microinverters.
• Run a PVsyst sensitivity study by ±15° to validate the chosen azimuth before it’s locked into the yield report.
• In NEM 3.0, model west-facing yield separately for export-value optimization.

Key Takeaways

• Azimuth is the compass orientation of a PV array; south (180°) optimal in the northern hemisphere.
• Yield drops as azimuth deviates from optimal, 10° deviation costs 1-2%, 45° costs 4-6%, 90° costs 15-18%.
• NEM 3.0 California shifts the economic preference slightly westward (high evening export rates).
• Mixed-orientation arrays need multiple MPPTs or microinverters.
• Always use true north (correct for magnetic declination).

Related Reading

Fixed-tilt azimuth is only half the orientation story, on single-axis trackers the array’s azimuth shifts through the day around a fixed north-south axis, and the backtracking algorithm explainer and auto solar tracking system guide both walk through how that changes the yield math versus a static azimuth.

Since a chosen azimuth is ultimately a bankability input, it’s worth validating in simulation before it’s locked, the PVsyst tracker yield study methodology and our broader roundup of PV yield simulation software both cover where the azimuth assumption enters the model, and any resulting swing shows up in the P50/P90/P99 yield report uncertainty lenders review.

Non-optimal azimuths on sloped or non-uniform rooftops also change wind loading patterns on the array, which the ASCE 7-22 wind load reading for solar rooftops covers in more depth.