SunYieldMap

How panel direction and tilt change solar output

By Emily CarterPublished Data as of 2026-10-27: PVWatts® v8, typical-year weather

In the median city on this site, panels facing east or west make about 14% less a year than the same panels facing south at a 20° tilt, and flat panels about 12% less. Tilting south-facing panels up to the city's latitude adds about 2%, and it is the best fixed layout in 99 of the 100 cities. A 1-axis tracker on the ground adds about 16%.

The six layouts side by side

Every city was modelled six times with the same 1 kW of panels: the reference roof (south, 20° tilt), south-facing at a tilt equal to the city's latitude, flat, east-facing at 20°, west-facing at 20°, and a 1-axis tracker. The table gives the median change against the reference roof across all 100 cities, and the range from the city with the lowest change to the city with the highest.

Change in yearly output against a south-facing 20° roof
LayoutMedianRange across cities
South, tilted to latitude+1.9%−0.1% (Honolulu) to +5.0% (Fargo)
1-axis tracker+15.9%+6.3% (Anchorage) to +21.7% (Honolulu)
Flat−11.7%−16.1% (Fargo) to −4.5% (Honolulu)
West, 20° tilt−14.1%−18.7% (Billings) to −7.6% (Honolulu)
East, 20° tilt−14.4%−18.2% (Fargo) to −7.0% (Honolulu)

Two things stand out. The fixed alternatives sit in a tight order: latitude tilt on top, then flat, then the two side-facing roofs, which are close to each other. And the spread inside each layout is wide: an east-facing roof loses 7.0% in Honolulu but 18.2% in Fargo. Denver shows the usual order: 1,602 kWh per kW at 20° south, 1,665 tilted to 40°, 1,375 flat, 1,361 east and 1,329 west.

Steeper tilt helps most in the north

Tilting south-facing panels to the city's latitude is the best fixed layout in 99 of the 100 cities. The exception is Honolulu, HI, where the 20° roof wins by a hair. The data shows why: its latitude is 21.3°, barely more than the reference, so the two layouts are almost the same roof.

The further north, the more a steeper tilt addsChange in yearly output from latitude tilt against a 20° roof, by city latitude
0%+2%+4%+6%20°30°40°50°60°City latitudeEl Paso, TX: latitude 31.8°, +1.8%Tucson, AZ: latitude 32.2°, +1.9%North Las Vegas, NV: latitude 36.3°, +3.2%Albuquerque, NM: latitude 35.1°, +2.5%Henderson, NV: latitude 36.0°, +2.7%Phoenix, AZ: latitude 33.6°, +2.0%Las Vegas, NV: latitude 36.2°, +2.8%Chandler, AZ: latitude 33.3°, +1.9%Mesa, AZ: latitude 33.4°, +1.9%Gilbert, AZ: latitude 33.3°, +1.8%Chula Vista, CA: latitude 32.6°, +1.6%Riverside, CA: latitude 33.9°, +1.7%Bakersfield, CA: latitude 35.4°, +1.3%San Diego, CA: latitude 32.8°, +1.5%Los Angeles, CA: latitude 34.0°, +1.6%Long Beach, CA: latitude 33.8°, +1.5%Santa Ana, CA: latitude 33.7°, +1.6%Anaheim, CA: latitude 33.9°, +1.5%Reno, NV: latitude 39.5°, +3.0%Irvine, CA: latitude 33.7°, +1.8%Fresno, CA: latitude 36.8°, +1.3%Colorado Springs, CO: latitude 38.9°, +4.0%Stockton, CA: latitude 38.0°, +1.3%San Jose, CA: latitude 37.3°, +1.4%Sacramento, CA: latitude 38.6°, +1.5%Aurora, CO: latitude 39.7°, +4.0%Denver, CO: latitude 39.8°, +4.0%Honolulu, HI: latitude 21.3°, −0.1%Oakland, CA: latitude 37.8°, +1.9%Tampa, FL: latitude 28.0°, +0.8%Miami, FL: latitude 25.8°, +0.4%Cheyenne, WY: latitude 41.1°, +4.7%San Francisco, CA: latitude 37.8°, +1.8%Arlington, TX: latitude 32.7°, +1.4%Corpus Christi, TX: latitude 27.7°, +0.2%Oklahoma City, OK: latitude 35.5°, +2.1%Fort Worth, TX: latitude 32.8°, +1.5%Plano, TX: latitude 33.1°, +1.4%Wichita, KS: latitude 37.7°, +2.7%New Orleans, LA: latitude 30.1°, +1.0%Orlando, FL: latitude 28.4°, +0.7%San Antonio, TX: latitude 29.5°, +0.6%Dallas, TX: latitude 32.8°, +1.2%Salt Lake City, UT: latitude 40.8°, +2.7%Austin, TX: latitude 30.3°, +0.5%Lincoln, NE: latitude 40.8°, +4.2%Tulsa, OK: latitude 36.1°, +2.0%Boise, ID: latitude 43.6°, +2.6%Jacksonville, FL: latitude 30.3°, +0.8%Charleston, SC: latitude 32.8°, +1.2%Kansas City, MO: latitude 39.1°, +3.1%Greensboro, NC: latitude 36.1°, +2.1%Memphis, TN: latitude 35.1°, +1.6%Virginia Beach, VA: latitude 36.8°, +1.9%Omaha, NE: latitude 41.3°, +4.1%Jackson, MS: latitude 32.3°, +0.9%Houston, TX: latitude 29.8°, +0.5%Atlanta, GA: latitude 33.8°, +1.2%Sioux Falls, SD: latitude 43.5°, +4.9%Baltimore, MD: latitude 39.3°, +2.8%Washington, DC: latitude 38.9°, +2.9%Charlotte, NC: latitude 35.2°, +1.8%St. Louis, MO: latitude 38.6°, +2.2%Huntsville, AL: latitude 34.7°, +1.5%Little Rock, AR: latitude 34.7°, +1.3%Raleigh, NC: latitude 35.8°, +1.8%Des Moines, IA: latitude 41.6°, +3.5%Wilmington, DE: latitude 39.7°, +2.8%Durham, NC: latitude 36.0°, +2.1%New York, NY: latitude 40.7°, +3.5%Philadelphia, PA: latitude 40.0°, +2.9%Louisville, KY: latitude 38.2°, +2.1%Lexington, KY: latitude 38.0°, +1.9%Nashville, TN: latitude 36.2°, +1.5%Milwaukee, WI: latitude 43.1°, +3.2%Billings, MT: latitude 45.8°, +4.7%Chicago, IL: latitude 41.8°, +2.5%Minneapolis, MN: latitude 45.0°, +4.8%Indianapolis, IN: latitude 39.8°, +2.3%St. Paul, MN: latitude 44.9°, +5.0%Portland, ME: latitude 43.7°, +4.6%Madison, WI: latitude 43.1°, +2.6%Newark, NJ: latitude 40.7°, +2.9%Jersey City, NJ: latitude 40.7°, +2.7%Fargo, ND: latitude 46.9°, +5.0%Columbus, OH: latitude 40.0°, +2.0%Detroit, MI: latitude 42.4°, +2.1%Providence, RI: latitude 41.8°, +3.6%Bridgeport, CT: latitude 41.2°, +2.6%Boston, MA: latitude 42.3°, +3.1%Cincinnati, OH: latitude 39.1°, +2.1%Manchester, NH: latitude 43.0°, +4.6%Cleveland, OH: latitude 41.5°, +1.3%Burlington, VT: latitude 44.5°, +3.8%Charleston, WV: latitude 38.3°, +1.4%Buffalo, NY: latitude 42.9°, +1.8%Pittsburgh, PA: latitude 40.4°, +1.2%Portland, OR: latitude 45.5°, +0.6%Seattle, WA: latitude 47.6°, +0.9%Anchorage, AK: latitude 61.2°, +3.3%HonoluluFargoAnchorage

The gain grows with latitude (correlation 0.68). It reaches +5.0% in Fargo, ND, at 46.9° north. Twelve cities gain less than 1%. Most are in Florida, on the Gulf Coast and in south Texas, but Seattle (+0.9%) and Portland (+0.6%) are on the list too, far to the north. Their winters, when a steeper tilt helps most, add little to the year: they make 31% and 29% as much from December to February as from June to August. A steeper panel faces the low winter sun more squarely and the high summer sun less squarely, and the monthly figures show the trade: in the median city, latitude tilt changes December output by +20.2% and June output by −9.7% compared with the 20° roof. Over a year the winter gain wins, but only modestly.

Flat panels lose most where the winter sun is low

Laying panels flat loses 11.7% of yearly output in the median city. The loss tracks latitude even more closely than the tilt gain does (correlation −0.85): it is largest in Fargo, ND (−16.1%) and the other northern-plains cities, and smallest in Honolulu, HI (−4.5%).

The monthly split is lopsided. In the median city a flat array changes December output by −34.9% against the 20° roof, but June output by +3.0%. Flat panels actually beat the 20° roof in June in 95 of the 100 cities; they lose the year because of the winter months.

East or west: nearly a tie, with a regional pattern

East- and west-facing roofs lose about the same amount against south: a median of −14.4% for east and −14.1% for west. Between the two, west makes more in 45 cities and east in 55. The gap is small everywhere. The largest west lead is in Santa Ana, CA, 6.5% of the reference output, and the largest east lead is in Orlando, FL, 5.0%.

Where west-facing panels beat east-facing panels, by Census division
DivisionCitiesWest ahead inMedian west − east
West North Central109 of 10+0.9%
Pacific1917 of 19+3.4%
West South Central1310 of 13+1.7%
East North Central83 of 8−0.7%
East South Central62 of 6−0.2%
Middle Atlantic61 of 6−0.7%
New England61 of 6−0.5%
South Atlantic152 of 15−0.9%
Mountain170 of 17−2.0%

West − east is the difference between the two layouts as a share of the city's reference output.

The pattern is geographic. West wins in almost all Pacific and West North Central cities, and east wins in all of the Mountain cities and most of the South Atlantic. The model runs on hourly typical-year weather, so a west lead means that city's weather file gives the panels more usable sun in the afternoon than in the morning. The data does not record why. If your roof faces east or west, the city page lists both figures, and the panel direction table has every city.

Where a tracker adds the most

A 1-axis tracker turns the panels from east to west through the day. It is a ground mount, not a roof option, and the site shows it only for comparison. It adds +15.9% in the median city, from +6.3% in Anchorage, AK to +21.7% in Honolulu, HI. By Census region the median gain is +18.0% in the West, +16.1% in the South, +14.3% in the Midwest and +13.4% in the Northeast. The rankings list the 15 cities where it helps most.

To see all six layouts for one city, open its page or pick the city in the yield estimator and switch layouts: the yearly total, the monthly bars and the city's rank update for each one.

Sources

  • PVWatts® Calculator API v8, National Laboratory of the Rockies (NLR, formerly NREL): developer.nlr.gov. 600 model runs (100 cities × 6 layouts), retrieved 2026-10-27.
  • Weather: NSRDB typical-meteorological-year data returned by PVWatts® (NSRDB PSM V3 GOES tmy-2020 3.2.0, NSRDB PSM V4 Polar tmy-2023 1.0.0).
  • City list and locations: U.S. Census Bureau, Vintage 2024 Population Estimates for incorporated places (SUB-EST2024) and U.S. Census Bureau, 2024 Gazetteer Files - Places (census.gov).
  • Every figure in this guide is computed by SunYieldMap from those model runs. Settings and limits are in the methodology.