liminfoSolar Panel Tilt Calculator
Free web tool: Solar Panel Tilt Calculator
Annual Average
Best year-round production
40.0°
Spring/Fall
Equinox optimal
40.0°
Summer
Sun is higher; reduce tilt
25.0°
Winter
Sun is lower; increase tilt
55.0°
Max Winter Production
Aggressive winter optimization
65.0°
Rules of Thumb:
- Annual optimal tilt ≈ latitude
- Summer: latitude − 15°
- Winter: latitude + 15°
- Azimuth: Due south (northern hemisphere) or due north (southern hemisphere)
About Solar Panel Tilt Calculator
The Solar Panel Tilt Calculator determines the optimal installation angle for photovoltaic (PV) panels based on your geographic latitude. By entering your latitude in decimal degrees, you instantly receive five tilt angle recommendations: an annual average for year-round balance, spring/fall equinox optimization, a reduced summer angle when the sun tracks higher in the sky, an increased winter angle to capture lower solar paths, and an aggressive winter optimization setting for maximum cold-season production. Quick-select city presets for Miami, Los Angeles, New York, London, Berlin, and ten other global locations make it easy to benchmark different installation sites.
Solar installers, homeowners planning rooftop PV systems, agricultural engineers designing greenhouse heating, and renewable energy students all rely on accurate tilt calculations to maximize energy harvest. The core principle is straightforward: annual optimal tilt equals the site latitude in degrees. Seasonal adjustments subtract 15° in summer (sun is higher) and add 15° in winter (sun is lower), with an aggressive winter setting adding 25° beyond latitude. Panel azimuth should face due south in the northern hemisphere and due north in the southern hemisphere for maximum daily sun exposure.
All calculations execute entirely within your browser using JavaScript. No data is transmitted to external servers, and no registration is required. The interface renders correctly in dark mode and adapts to desktop, tablet, and mobile screen sizes, making it practical for field use on smartphones when evaluating installation sites in person.
Key Features
- Five seasonal tilt presets: annual average, spring/fall, summer, winter, and aggressive winter optimization
- Latitude input with one-decimal-degree precision from -90° to +90°
- Quick-select city buttons for 12 global locations from Miami (25.8°) to Stockholm (59.3°)
- Real-time recalculation as latitude value changes, with no button press required
- Clear rule-of-thumb reference panel showing latitude ± 15° seasonal guidelines
- Azimuth guidance for both northern and southern hemisphere installations
- Color-coded result cards showing angle in large bold text for easy field reading
- 100% client-side — no data ever leaves your browser, no account needed
Frequently Asked Questions
What is the optimal tilt angle for solar panels?
The annual optimal tilt angle for a solar panel is approximately equal to the site's latitude in degrees. For example, a location at 40° latitude should mount panels at roughly 40° from horizontal. Seasonal adjustments improve output: subtract 15° in summer (tilt ≈ latitude − 15°) and add 15° in winter (tilt ≈ latitude + 15°) to track the sun's changing elevation.
Why does the solar panel tilt angle change by season?
The sun's altitude above the horizon changes throughout the year due to Earth's axial tilt of 23.5°. In summer, the sun rises much higher in the sky, so a flatter panel angle (latitude − 15°) receives more direct irradiance. In winter, the sun stays low, so a steeper angle (latitude + 15°) catches more of its rays. Adjusting seasonally can improve annual energy yield by 5–10% compared to a fixed optimal-average tilt.
Which direction should solar panels face?
In the northern hemisphere, panels should face true south (azimuth 180°) to maximize daily sun hours. In the southern hemisphere, panels should face true north (azimuth 0°). Deviations of up to 20–30° east or west reduce output only modestly, but significant deviation from true south/north can cut production by 10–20%.
How do I find my latitude for this calculator?
You can find your latitude from Google Maps (right-click your location and select the coordinates shown), a GPS device, smartphone location settings, or by selecting the nearest city from the quick-select presets in this calculator. The calculator accepts values from −90° (South Pole) to +90° (North Pole) with one-decimal precision.
What is the aggressive winter optimization setting?
The aggressive winter optimization adds 25° to your latitude instead of the standard 15°. For example, at 45° latitude it recommends 70° tilt. This maximizes energy capture during winter months and is useful for systems designed to compensate for high winter electricity demand, though it comes at the cost of reduced spring, summer, and fall production.
Does roof pitch affect solar panel tilt recommendations?
Yes. If your roof already has a slope, the effective panel tilt combines the roof pitch with any additional racking angle. For a roof pitched at 20° facing south, installing panels flush would give a 20° tilt. You would need racking that adds 20° more to reach a 40° tilt at a 40° latitude site. This calculator provides target tilt values; a solar installer will help you design racking to achieve them on your specific roof.
Is this calculator accurate for flat commercial rooftops?
Yes, the tilt angle recommendations apply to any installation — residential rooftops, flat commercial buildings, ground-mounted arrays, or carport canopies. Flat roof installations have the advantage of freely choosing any tilt angle, making the latitude-based recommendations directly applicable. The calculator is particularly valuable for flat-roof PV planning.
What is the difference between tilt angle and azimuth angle?
Tilt angle (or inclination) is the angle of the panel relative to horizontal — 0° is flat, 90° is vertical. Azimuth angle is the compass direction the panel faces — 180° is due south in the northern hemisphere. This calculator provides tilt angle recommendations. For most installations in the northern hemisphere, azimuth should be set to due south (180°), and this is noted in the rules-of-thumb section of the tool.