Quick answer: In the United States, a good fixed tilt angle for solar panels is roughly 0.76 × your latitude + 3.1 degrees, with the panels facing true south. Enter your ZIP code below to get an estimated angle, plus seasonal starting estimates. Outside the US, enter latitude manually: positive for north and negative for south. The simplified tool supports 15°–72° in either hemisphere; it does not calculate a site-specific optimum.
Solar Panel Tilt Angle Calculator: US ZIP or Latitude
Or enter latitude manually
3. Mounting on a roof? (optional)
How to Use This Solar Panel Angle Calculator
You do not need any solar knowledge. It takes about 30 seconds.
- Enter your location. Type your 5-digit ZIP code, such as 80202, and the result appears automatically. No ZIP code handy? Tap “Use my location,” or open “Or enter latitude manually” and type your latitude (in Google Maps, right-click your spot and the first number shown is the latitude).
- Choose what matters most. Pick “Best all year” if you are connected to the power grid and want the most total energy. Pick “Winter power” if you live off-grid and need your batteries to stay charged when the sun is weakest. Pick “Summer power” if you mostly use your system in warm months, for example at a summer cabin.
- Optional: add your roof. Select your roof pitch (for example 6:12) and the direction your roof faces. The calculator will tell you how close your roof already is to the ideal angle.
- Read your result. The big number is the angle to set your panels at, measured from flat ground. The picture shows how steep that looks. The four boxes show the angle for each season, and “Copy my results” saves a summary you can share with your installer.
What Is the Optimal Tilt Angle for Solar Panels?
The best tilt depends mainly on latitude, because it decides how high the sun climbs. Panels produce the most when sunlight hits them close to straight on. For a fixed array, a widely used rule of thumb is 0.76 × latitude + 3.1° (and 0.87 × latitude for latitudes below 25°). For a seasonal setup, a common rule is latitude minus 15° for summer and latitude plus 15° for winter. Sources differ slightly in their coefficients, and the loss from being a few degrees off is usually small, so treat the result as a rough starting point rather than an exact optimum.
| City | Year-round tilt | Winter tilt | Summer tilt |
|---|---|---|---|
| Miami, FL | 23° | 41° | 11° |
| Dallas, TX | 28° | 48° | 18° |
| Phoenix, AZ | 29° | 48° | 18° |
| Denver, CO | 33° | 55° | 25° |
| New York, NY | 34° | 56° | 26° |
| Chicago, IL | 35° | 57° | 27° |
| Seattle, WA | 39° | 63° | 33° |
Which Direction Should Solar Panels Face?
In the Northern Hemisphere, face true south, not magnetic south. A phone or pocket compass points to magnetic north, and the gap (declination) can be several degrees depending on where you live. Look up your offset with the NOAA calculator linked above. If your roof faces southeast or southwest, it still works well. East or west roofs produce more in the morning or afternoon and usually less overall. North-facing roofs are the weakest choice in the US.
Off-Grid vs Grid-Tied: Which Tilt Should You Choose?
A grid-tied home mostly wants the most total energy over the year, so the year-round tilt fits. An off-grid system is different: it must keep batteries charged when the sun is weakest, which is winter. Many off-grid builders therefore choose a steeper winter-focused tilt and accept less summer output, because summer usually has energy to spare. A steeper angle can also help snow slide off. If you adjust by hand, April and October are rough Northern Hemisphere changeover points, not universal dates. Southern Hemisphere seasons are reversed; compare local monthly output and use only safely accessible, suitable mounts.
Roof Pitch to Degrees
Roof pitch is written as rise over 12 inches of run. Compare the roof angle with the estimate in a production model. An angle comparison cannot establish the safety or suitability of a mounting system; have structure, wind loading and local requirements checked.
| Pitch | 3:12 | 4:12 | 5:12 | 6:12 | 7:12 | 8:12 | 9:12 | 10:12 | 12:12 |
|---|---|---|---|---|---|---|---|---|---|
| Angle | 14.0° | 18.4° | 22.6° | 26.6° | 30.3° | 33.7° | 36.9° | 39.8° | 45.0° |
Does a “33% rule” determine solar panel tilt?
No. A percentage mentioned in a solar proposal may concern inverter DC-to-AC sizing or a jurisdiction-specific roof-layout rule. It does not establish the optimal tilt. Ask which equipment specification or current local code the percentage refers to; do not apply a rule from another country or permit authority to your roof. Use the actual roof geometry and a production model for the tilt comparison.
Is Adjusting Your Solar Panel Tilt Seasonally Worth It?
Compare two production models for your location: the existing fixed angle and a practical seasonal schedule. Keep capacity, losses, shading and other inputs identical. Compare the months when extra energy is useful, then consider racking cost, safe access and maintenance. There is no universal percentage gain. An off-grid system may value winter charging more than the largest annual total; a grid-connected household may value energy when it can use it.
Common Mistakes to Avoid
- Using a magnetic compass without correcting for declination.
- Ignoring shade. A few hours of shade can matter more than a few degrees of tilt.
- Choosing a very low tilt that lets dust and water sit on the glass. Most guidance suggests at least about 10 degrees.
- Treating any tilt calculator as a production estimate. Use PVWatts for expected kWh.
How This Calculator Works (Explained Simply)
The best angle for a solar panel depends on how high the sun climbs in the sky where you live. Near the equator the sun is almost overhead, so panels sit fairly flat. Farther from the equator the sun stays lower, so panels need to lean more steeply to face it. How far north you are is measured by your latitude, and every ZIP code has one. The calculator follows three simple steps:
- It looks up the latitude for your ZIP code.
- It puts that latitude into well-known rules of thumb used by solar installers.
- It shows the answer for the whole year and for each season.
Worked example: ZIP code 80202 (Denver, Colorado), latitude 39.7°
| Result | Calculation | Answer |
|---|---|---|
| Year-round | 0.76 × 39.7 = 30.2, then + 3.1 | 33° |
| Winter | 39.7 + 15 | 55° |
| Spring / Fall | Same as latitude | 40° |
| Summer | 39.7 − 15 | 25° |
How roof pitch is converted: a pitch of 6:12 means the roof rises 6 inches for every 12 inches it runs sideways. Using basic geometry, that equals about 26.6°. Use the calculated roof angle in a production model; the angular difference alone cannot approve a mounting design.
What the calculator does not do: it cannot see shade from trees or buildings, local weather, or how much electricity you use, and it does not predict how much power you will make. For that, use PVWatts. A few brand-new or PO-box-only ZIP codes may be missing, so enter your latitude manually if that happens.
In technical terms, it finds the latitude of your ZIP code (an approximate center point of the ZIP area), then applies the rules above: year-round = 0.76 × latitude + 3.1 (0.87 × latitude below 25°); spring and fall = latitude; winter = latitude + 15 (capped at 80°); summer = latitude − 15 (minimum 10°). It does not model shading, weather or your electricity use, and a few ZIP codes (new or PO-box-only ones) may be missing. In that case enter your latitude manually.
Frequently Asked Questions
What is the optimal tilt angle for solar panels?
There is no single angle for the whole country. A fixed-tilt rule of thumb is 0.76 × latitude + 3.1 degrees, which gives roughly 23° in Miami and 39° in Seattle.
Should solar panels face true south?
In most of the US, yes. True south (180°) usually gives the most energy. Southeast or southwest is a good second choice.
What tilt is best in winter?
Latitude plus about 15 degrees is the common winter rule. It suits off-grid systems that must perform when the sun is low.
Is there an app that can measure the tilt angle of my solar panels?
Yes. Many smartphones have a built-in level or inclinometer, and free inclinometer apps are available. Only measure an accessible surface when it is safe and permitted by the equipment instructions. Do not climb onto a roof or touch electrical components to obtain an angle.
What is the 33% rule in solar panels?
It is not a tilt formula. Ask whether the percentage refers to inverter sizing or a specific local roof-layout requirement, and verify the applicable equipment documentation or local code.
Does the tilt angle change by ZIP code?
Yes, because ZIP codes sit at different latitudes. The farther north you are, the steeper the recommended angle.
Is it worth adjusting solar panel tilt seasonally?
Compare modeled monthly energy at fixed and seasonal angles for your site. There is no universal percentage gain; weigh useful extra energy against racking, access and maintenance.
Should I tilt my roof panels or keep them flush with the roof?
Compare modeled energy at the existing roof angle before considering tilt racks. Mounting must also satisfy structural, wind, drainage and local requirements; an angle difference alone does not establish suitability.
After You Set the Angle: Plan the Wiring
Once your panels are tilted correctly, the next thing that decides how much power actually reaches your batteries or inverter is the wiring. Long or thin cable runs waste energy as heat, especially on 12V, 24V, and 48V systems. Use our voltage drop and wire size calculator to check the cable size for your panels, battery, and inverter before you buy.
Already have an installed system with wiring or production problems, and your installer has closed? Our guide to warranty and repair options when your solar installer is out of business explains who to contact first and what documents to gather.
Sources and Further Reading
- Green Building Advisor, “Is it worth the cost of adjustable tilt racks for PV?”: greenbuildingadvisor.com
- Northern Arizona Wind & Sun forum, “Is adjustable tilt worth it?”: forum.solar-electric.com
- PVWatts Calculator: pvwatts.nrel.gov
- NOAA magnetic declination calculator: ngdc.noaa.gov
- BGR, “What Is The 33% Rule For Solar Panels?”: bgr.com
- Coulee Energy, “Solar Panel Oversizing Guide”: couleenergy.com
- Solar Permit Solutions, “Solar Panel 33 Percent Rule Explained”: solarpermitsolutions.com
Last updated: October 29, 2026. This page is educational, not engineering or electrical advice. Roof loading, wind, snow and electrical work must follow local codes and a licensed professional.
How to use your ZIP-code result on a real roof. Suppose your ZIP lookup gives a latitude of 40° N. The annual formula above estimates a tilt of about 33.5° from horizontal. A 6:12 roof slopes about 26.6°, so flush-mounted panels would sit roughly 7° flatter than the estimate. Direction is a separate input: two sides of the same roof share a ZIP code and pitch, yet one can face east and the other west. Enter the direction of the actual roof face. A 7° tilt difference does not imply a 7% energy loss. To compare expected production on those two roof faces, model each with its own tilt and direction in PVWatts.
Using this panel-angle estimate in a real off-grid design? Continue with our 200W panel and 100Ah battery charging example or the solar well pump kit sizing guide to connect panel planning to actual system loads.
Using latitude outside the United States
US ZIP lookup remains available. For other locations, use a signed latitude between 15° and 72° from the equator. Sydney at approximately −33.87° gives an annual starting estimate of 29°, facing true north; London at approximately +51.51° gives 42°, facing true south. These use the same absolute-latitude rule, not local weather optimization. Near the equator and in polar regions, this simplified seasonal tool intentionally asks you to use a location-specific model instead.
In the Southern Hemisphere, the labels winter and summer refer to your local seasons. Do not copy a US calendar schedule into an Australian installation. Tilt measures the angle above horizontal; azimuth measures compass direction. Enter both correctly in PVWatts and compare the actual roof orientation before making a mounting decision. A latitude result cannot assess wind loading, roof condition, drainage, shading or local approvals.
For the next planning step, use the panel-to-battery charging example to distinguish peak sun hours from daylight hours. If the aim is water supply, the solar well-pump storage guide explains how a tank can bridge days when pumping falls short. An estimated angle alone cannot establish either daily energy or water delivery.