Solar Panel Tilt Angle Calculator

Before You Set an Angle: What You Are Optimising

Tilt is a trade between seasons. A flatter angle favours summer, when the sun rides high; a steeper angle favours winter, when it stays low. Setting tilt equal to latitude splits the difference for the best annual total, which is what fixed rooftop systems want. Know two more things before instructing anyone: your roof's own pitch (a 20° south-facing roof in Nagpur is already nearly perfect, so no extra structure is worth paying for), and whether your use is season-critical: an off-grid farm that must survive December should bias 5 to 10° steeper than latitude, sacrificing summer surplus it does not need.

Worked Example: Setting Tilt in Kolkata

Kolkata sits at 22.6°N. The calculator returns a fixed tilt of 23°, facing true south at azimuth 180°. A seasonal-adjustment structure would use 38° from October to February and 8° from March to September, worth 4 to 8% more energy per year: roughly 180 to 350 extra units on a 5 kW system, which rarely repays the costlier structure for a grid-connected home. The practical note for Kolkata's flat terraces: never lay panels at less than 10° even though 8° is the summer optimum, because below 10° the monsoon stops cleaning the glass for you.

Using the Angle: Instructions for Installation Day

• Write the angle into the work order. "As per site" on a quote often becomes whatever the structure batch was welded at; specify the degree figure.
• Ask for true south, not compass south. Installers should correct for magnetic declination; a phone compass alone can be several degrees off near metal structures.
• Check row spacing against the tilt. Steeper panels cast longer winter shadows; the layout drawing should show December shadow lines clearing the row behind, which affects your roof area budget.
• Verify with a spirit-level app. After installation, two minutes with a phone on the frame confirms the built angle matches the design.

Tilt and Orientation Mistakes

• Chasing the last degree. ±5° of ideal costs under 1% of output; do not pay for custom structures to fix a 3° "error".
• Laying panels flat for looks. Below 10°, soiling losses climb past anything the angle math saves; flat installs also pond water at the frame edge.
• Facing the driveway, not the sun. Aesthetics sometimes rotate arrays toward the street. Every 45° away from south costs roughly 5 to 10% annually.
• Copying a northern design in the south. A Delhi-spec 29° structure installed in Kochi overshoots the 10° ideal and wastes structure steel; angle specs do not travel between cities.

How This Tilt Angle Calculator Works