Which states have the most solar potential? Here’s a roundup of the states with the best natural solar resources, the best solar incentives for homeowners, and the greatest amount of solar power already installed.
By Megan Phelps
September 16, 2009
Image GalleryA PV array in Arizona — one of the best places in the United States for generating solar power.
ISTOCKPHOTO/ THOMAS POLEN
Image GalleryPrintE-mailCommentsRSS Wherever there’s sunlight, you can take advantage of solar energy. However, different places have different solar resources, so the same set of photovoltaic (PV) panels will produce much more electricity in some locations than in others.
Many factors make a difference in how much electricity a PV system can produce at any one time — including constantly changing factors such as time of day, season and weather, but also geographic traits such as climate and latitude. In general, areas closer to the equator have far greater potential for producing solar electricity than those closer to the poles, and areas with consistent sun have greater solar potential then areas that are frequently overcast.
As a whole, the United States has terrific solar resources. For perspective, check out this map of global solar radiation from the United Nations Environment Programme. Now consider that Germany and Spain lead the world in installed PV power. The United States is currently third in installed PV power worldwide, but has far greater natural solar resources than either Spain or Germany.
But while the United States has strong solar potential across the country, some states are definitely sunnier than others. Here’s how you can find out which states have the best natural solar resources, and which have policies that support the development of solar power.
Naturally Sunny States
For the absolute best solar resources in the United States, think southwest.
Take a look at this solar resources map from the National Renewable Energy Laboratory (NREL). Based on this map, New Mexico and Arizona are red hot with solar potential, and California, Nevada, Texas, Utah and Colorado also have large areas highly favorable for PV development. PV systems will generate more electricity in these spots — and therefore earn more money — than PV panels in areas with fewer natural solar resources.
Both this U.S. map and the global map mentioned above use a common measurement of solar irradiation, which is kwh/m2/day, also known as peak sun hours. Here’s more information about peak sun hours and how you can calculate them for your location using the PV Watts1 website.
For yet another look at solar resources state-by-state, check out the U.S. Energy Information Administration (EIA) state energy profiles. This is a set of maps and energy profiles of all 50 states. Any areas with above six peak sun hours per day are shaded on the maps to indicate that they are good sites to consider for future solar projects.