## Understanding Peak Sun Hours

I get asked all the time, **“How much solar energy can I expect to produce in my area?”** and **“How sunny is my area?”**

We answer that question with Peak Sun Hours. **Peak Sun Hours is the technical term we use to describe the amount of sunlight a location receives. It’s not just the number of hours between sunrise and sunset, but it takes into account cloud cover, weather patterns, and more.**

The super technical definition is that it’s the number of hours of sunlight at 1,000 watts per square meter (1 kW/m²) – the standard testing condition for rating solar panels.

Throughout the day, sunlight intensity varies dramatically. Early morning and late evening provide lower intensity (200-500 W/m²), while midday can exceed 1,000 W/m² in ideal conditions. Peak sun hours aggregate all this varying sunlight into equivalent hours at peak intensity. For example, receiving 500 W/m² for 2 hours equals 1 peak sun hour (500 × 2 = 1,000).

Of course, sunlight varies dramatically by time of year and location. You’ll really enjoy using our interactive tool below to see how your region compares to others. For example, Phoenix, Arizona produces 35% more solar energy than Chicago, Illinois.

**How to Read This Data:** The grid below shows the total solar energy production per month for a 10kW system in each city. This monthly energy production directly correlates to the peak sun hours available in that location. Higher monthly energy values indicate more peak sun hours and better solar potential for your investment.

## Select Cities to Compare

- Charlotte, NC
- Phoenix, AZ
- Mesa, AZ
- Los Angeles, CA
- San Diego, CA
- San Francisco, CA
- San Jose, CA
- Sacramento, CA
- Miami, FL
- Tampa, FL
- Orlando, FL
- Jacksonville, FL
- Denver, CO
- Atlanta, GA
- Boston, MA
- Austin, TX
- Houston, TX
- Dallas, TX
- San Antonio, TX
- Chicago, IL
- New York, NY
- Philadelphia, PA
- Pittsburgh, PA
- Richmond, VA
- Charleston, SC
- Columbia, SC
- Raleigh, NC
- Durham, NC
- Portland, ME
- New Haven, CT
- Providence, RI
- Newark, NJ
- Baltimore, MD
- Columbus, OH
- Cincinnati, OH
- Cleveland, OH
- Detroit, MI

### Phoenix

AZ

Annual Production

17,662 kWh

100

75

50

25

0

Jan: 38.3 kWh/day

Feb: 42.2 kWh/day

Mar: 50 kWh/day

Apr: 57.4 kWh/day

May: 58.3 kWh/day

Jun: 57.9 kWh/day

Jul: 50.8 kWh/day

Aug: 49.9 kWh/day

Sep: 49.6 kWh/day

Oct: 45.6 kWh/day

Nov: 41.2 kWh/day

Dec: 37.8 kWh/day

### Chicago

IL

Annual Production

13,080 kWh

100

75

50

25

0

Jan: 21.1 kWh/day

Feb: 28.8 kWh/day

Mar: 35.1 kWh/day

Apr: 42.4 kWh/day

May: 44.9 kWh/day

Jun: 48.5 kWh/day

Jul: 51.2 kWh/day

Aug: 44.8 kWh/day

Sep: 40.2 kWh/day

Oct: 30.2 kWh/day

Nov: 23.2 kWh/day

Dec: 18.4 kWh/day

15,371

Average Annual kWh

Across selected cities

Phoenix

Best Performance

17,662 kWh/year

35%

Production Range

Best vs. lowest performer

## Solar Production Rankings

Annual production for 10kW systems across all service areas

| Rank | City | Annual Production | Daily Average | Best Month | Worst Month |
| --- | --- | --- | --- | --- | --- |
| 1 | [Phoenix, AZ](/content/local/arizona/phoenix/index.html) | 17,662 kWh | 48.4 kWh | May: 58.3 kWh/day | Dec: 37.8 kWh/day |
| 2 | [Mesa, AZ](/content/local/arizona/mesa/index.html) | 17,551 kWh | 48.1 kWh | May: 58.2 kWh/day | Jan: 37.6 kWh/day |
| 3 | [Los Angeles, CA](/content/local/california/los-angeles/index.html) | 16,861 kWh | 46.2 kWh | Aug: 56.2 kWh/day | Dec: 32.4 kWh/day |
| 4 | [San Jose, CA](/content/local/california/san-jose/index.html) | 16,473 kWh | 45.1 kWh | Jul: 60.5 kWh/day | Jan: 26.2 kWh/day |
| 5 | [Sacramento, CA](/content/local/california/sacramento/index.html) | 16,267 kWh | 44.6 kWh | Jul: 59.6 kWh/day | Dec: 23.9 kWh/day |
| 6 | [San Diego, CA](/content/local/california/san-diego/index.html) | 16,045 kWh | 44.0 kWh | Aug: 51.7 kWh/day | Dec: 33.4 kWh/day |
| 7 | [Denver, CO](/content/local/colorado/denver/index.html) | 15,992 kWh | 43.8 kWh | Jun: 53.4 kWh/day | Dec: 31 kWh/day |
| 8 | [Tampa, FL](/content/local/florida/tampa/index.html) | 15,772 kWh | 43.2 kWh | Apr: 50.5 kWh/day | Dec: 35.5 kWh/day |
| 9 | [San Francisco, CA](/content/local/california/san-francisco/index.html) | 15,693 kWh | 43.0 kWh | Jun: 55.7 kWh/day | Dec: 25.7 kWh/day |
| 10 | [Miami, FL](/content/local/florida/miami/index.html) | 15,539 kWh | 42.6 kWh | Mar: 49.2 kWh/day | Dec: 35.4 kWh/day |
| 11 | [Orlando, FL](/content/local/florida/orlando/index.html) | 15,485 kWh | 42.4 kWh | Apr: 49.5 kWh/day | Dec: 34.3 kWh/day |
| 12 | [Dallas, TX](/content/local/texas/dallas/index.html) | 15,091 kWh | 41.3 kWh | Jun: 50.5 kWh/day | Dec: 31.9 kWh/day |
| 13 | [San Antonio, TX](/content/local/texas/san-antonio/index.html) | 15,000 kWh | 41.1 kWh | Jul: 49 kWh/day | Dec: 31.1 kWh/day |
| 14 | [Austin, TX](/content/local/texas/austin/index.html) | 14,860 kWh | 40.7 kWh | Aug: 49.7 kWh/day | Dec: 32 kWh/day |
| 15 | [Jacksonville, FL](/content/local/florida/jacksonville/index.html) | 14,671 kWh | 40.2 kWh | Apr: 47.6 kWh/day | Dec: 30 kWh/day |
| 16 | [Charleston, SC](/content/local/south-carolina/charleston/index.html) | 14,626 kWh | 40.1 kWh | May: 48.2 kWh/day | Dec: 27.7 kWh/day |
| 17 | [Columbia, SC](/content/local/south-carolina/columbia/index.html) | 14,535 kWh | 39.8 kWh | Jun: 47.6 kWh/day | Dec: 29.7 kWh/day |
| 18 | [Charlotte, NC](/content/local/north-carolina/charlotte/index.html) | 14,276 kWh | 39.1 kWh | Jun: 46.8 kWh/day | Dec: 27.6 kWh/day |
| 19 | [Houston, TX](/content/local/texas/houston/index.html) | 14,261 kWh | 39.1 kWh | Jul: 45.2 kWh/day | Dec: 27.8 kWh/day |
| 20 | [Atlanta, GA](/content/local/georgia/atlanta/index.html) | 14,093 kWh | 38.6 kWh | May: 46.7 kWh/day | Dec: 28.1 kWh/day |
| 21 | [Baltimore, MD](/content/local/maryland/baltimore/index.html) | 13,930 kWh | 38.2 kWh | Jul: 48.1 kWh/day | Dec: 24.8 kWh/day |
| 22 | [Raleigh, NC](/content/local/north-carolina/raleigh/index.html) | 13,923 kWh | 38.1 kWh | Apr: 45.2 kWh/day | Dec: 25.6 kWh/day |
| 23 | [Durham, NC](/content/local/north-carolina/durham/index.html) | 13,850 kWh | 37.9 kWh | Jun: 46.2 kWh/day | Dec: 28.1 kWh/day |
| 24 | [Richmond, VA](/content/local/virginia/richmond/index.html) | 13,607 kWh | 37.3 kWh | Jun: 47.2 kWh/day | Dec: 25.2 kWh/day |
| 25 | [Philadelphia, PA](/content/local/pennsylvania/philadelphia/index.html) | 13,588 kWh | 37.2 kWh | Jul: 47 kWh/day | Dec: 23 kWh/day |
| 26 | [Portland, ME](/content/local/maine/portland/index.html) | 13,193 kWh | 36.1 kWh | Jun: 45.9 kWh/day | Dec: 19.8 kWh/day |
| 27 | [Boston, MA](/content/local/massachusetts/boston/index.html) | 13,110 kWh | 35.9 kWh | Jul: 46.5 kWh/day | Dec: 19 kWh/day |
| 28 | [Newark, NJ](/content/local/new-jersey/newark/index.html) | 13,105 kWh | 35.9 kWh | Jun: 46.6 kWh/day | Dec: 21.9 kWh/day |
| 29 | [Columbus, OH](/content/local/ohio/columbus/index.html) | 13,093 kWh | 35.9 kWh | Jun: 47.7 kWh/day | Dec: 19.6 kWh/day |
| 30 | [Chicago, IL](/content/local/illinois/chicago/index.html) | 13,080 kWh | 35.8 kWh | Jul: 51.2 kWh/day | Dec: 18.4 kWh/day |
| 31 | [Providence, RI](/content/local/rhode-island/providence/index.html) | 13,032 kWh | 35.7 kWh | Jul: 45 kWh/day | Dec: 21.4 kWh/day |
| 32 | [New York, NY](/content/local/new-york/new-york/index.html) | 12,917 kWh | 35.4 kWh | Jun: 46 kWh/day | Dec: 20.4 kWh/day |
| 33 | [Detroit, MI](/content/local/michigan/detroit/index.html) | 12,890 kWh | 35.3 kWh | Jul: 49.3 kWh/day | Dec: 16.3 kWh/day |
| 34 | [New Haven, CT](/content/local/connecticut/new-haven/index.html) | 12,757 kWh | 35.0 kWh | Jul: 46.1 kWh/day | Dec: 21 kWh/day |
| 35 | [Cleveland, OH](/content/local/ohio/cleveland/index.html) | 12,731 kWh | 34.9 kWh | Jul: 50 kWh/day | Dec: 14.6 kWh/day |
| 36 | [Cincinnati, OH](/content/local/ohio/cincinnati/index.html) | 12,581 kWh | 34.5 kWh | Jun: 43.6 kWh/day | Dec: 21.1 kWh/day |
| 37 | [Pittsburgh, PA](/content/local/pennsylvania/pittsburgh/index.html) | 11,992 kWh | 32.9 kWh | Jul: 43.9 kWh/day | Dec: 17.8 kWh/day |

## Data Source: NREL’s PVWatts Database

All solar irradiance and energy production data displayed in this tool comes from the [National Renewable Energy Laboratory’s (NREL) PVWatts database](https://pvwatts.nrel.gov/). This comprehensive database takes into account numerous climate factors that affect solar energy production, including local weather patterns, atmospheric conditions, temperature variations, and seasonal changes.

The PVWatts system uses decades of meteorological data and sophisticated modeling to provide accurate estimates of solar potential across thousands of locations. This ensures that the peak sun hours and energy production figures you see reflect real-world conditions rather than theoretical maximums, giving you reliable data for making informed solar investment decisions.