About the Row Misalignment Check
Row misalignment analysis quantifies the additional shading loss caused by solar panel rows that are not perfectly aligned east-west — due to roof geometry constraints, obstacles, or installation error. Even small angular misalignments (5–10°) can cause significant inter-row shading during morning and evening hours.
How to calculate it
- 1Measure the actual row orientation angle (azimuth) versus true south.
- 2For each degree of misalignment, calculate the additional morning/evening shading using a sun-path diagram.
- 3Simulate annual shading loss at the actual azimuth vs due-south using irradiance simulation software.
- 4Quantify the yield penalty: each 10° of azimuth rotation from south typically costs 0.5–1.5% of annual yield (more at higher latitudes).
- 5Decide: if misalignment > 15°, a layout redesign or acceptance of the yield penalty is required.
Worked example
A terrace with walls at 10° from south (10° west of true south). Using PVGIS for Delhi (28.6°N): at south-facing (180°), yield = 1,490 kWh/kWp/year; at 190° (10° west of south), yield = 1,478 kWh/kWp — a 0.8% penalty. At 200° (20° west), yield = 1,445 kWh/kWp — a 3.0% penalty. Up to 10° misalignment is generally acceptable.
What you can calculate
- Angle ° deviation
- < 0.5° pass
- Shading impact
- QC protocol
Frequently asked questions
Should solar panels always face exactly south in India?
Due south maximises annual yield, but true east-west alignment is often impractical on real rooftops. Up to 15° east or west of south causes less than 2% yield loss in most Indian locations. West-facing panels (south-west to west, 225–270°) are sometimes preferred for afternoon peak generation in locations with high afternoon ToU tariffs — the peak generation aligns better with peak value even if total annual yield is 10–15% lower.
How does panel orientation affect morning vs afternoon generation?
South-facing panels are symmetrical: equal generation in the morning and afternoon. East-of-south orientation (e.g. 160–170°) shifts the generation peak slightly earlier — better for morning demand. West-of-south (190–200°) shifts peak later into the afternoon — better for late-afternoon and early-evening ToU peaks. For grid-stabilisation, west-facing panels are increasingly preferred in high-solar-penetration grids that have midday duck curves.
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