weatherbycounty

Best Counties for Solar Energy

Published May 2, 2026

Solar energy potential is heavily influenced by climate. The best counties for solar combine abundant sunshine, low cloud cover, and moderate temperatures that keep photovoltaic panels operating efficiently. While official solar irradiance maps are the gold standard, climate data provides strong directional signals about where the sun shines most reliably.

We built a solar climate index using NOAA normals as a proxy for solar potential. Counties with many extreme heat days tend to correlate with high sunshine hours. Low precipitation suggests fewer cloudy days. Moderate temperatures avoid the efficiency losses that panels experience in extreme heat.

The 25 Best Counties for Solar Energy

Imperial County, CA tops our solar climate index with a score of 98.4. The desert Southwest dominates the rankings, but some surprising counties in the Great Plains and Texas also score highly.

RankCountyStateSolar ScoreHeat Days/YearPrecip (in)Avg Temp (°F)
1Imperial CountyCA98.4180.062.9673.67999999999999
2Yuma CountyAZ97.9180.342857142857164.07666666666666774.05714285714286
3La Paz CountyAZ97.2177.959999999999985.33799999999999972.4
4Clark CountyNV96.4131.31256.91882352941176466.75625000000001
5Inyo CountyCA96141.640000000000017.67333333333333466.64
6Riverside CountyCA95.8139.827777777777787.948569.54444444444444
7Mohave CountyAZ95.7134.1258.21166666666666665.86666666666666
8Maricopa CountyAZ95.1167.220000000000039.42826086956521871.775
9Pinal CountyAZ94.2157.318181818181811.07000000000000270.10909090909091
10Loving CountyTX94.2131.611.0964.65
11Reeves CountyTX94.2131.611.0964.65
12Presidio CountyTX93.9130.72511.70566.25
13Brewster CountyTX93.7144.207692307692311.99500000000000367.93846153846152
14Winkler CountyTX93.7131.5511.9964.75
15Crane CountyTX93.612612.1366.3
16Pima CountyAZ93139.0999999999999713.40166666666666468.10000000000001
17Kings CountyCA92.9115.727.83500000000000163.65999999999999
18Ward CountyTX92.8137.9666666666666713.6265.03333333333335
19Pecos CountyTX92.7128.72513.97566.1
20Terrell CountyTX92.5121.212.01567
21Upton CountyTX92.2130.214.8266.9
22Greenlee CountyAZ91.8132.7515.63333333333333164.35
23El Paso CountyTX91.8113.566666666666668.73333333333333465
24Midland CountyTX91.5120.613.53000000000000165.35
25San Bernardino CountyCA90.4110.894444444444459.73277777777777764.85

Note

This ranking uses climate data as a proxy for solar potential. For actual solar installation decisions, consult NREL solar irradiance maps and local solar installers who can assess roof orientation, shading, and local incentives.

Methodology

The solar climate index weights three factors: sunshine proxy (40% — extreme heat days correlate with high sun hours), dryness (35% — low precipitation suggests fewer cloudy days), and temperature moderation (25% — panels operate most efficiently between 55-75°F ambient temperature). All data comes from NOAA Climate Normals 1991-2020.

Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. All figures represent 30-year averages and may differ from individual-year observations. Station-level data is aggregated to county level using spatial averaging.

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