Solar power is a great idea throughout most of the U.S. But the southwest offers the optimum conditions for solar power with more sunlight and heat than the rest of the country. This includes southern California, most of Nevada, western Texas, a wide swath of New Mexico, parts of Utah and Colorado. So it’s kind of surprising that there’s still a significant lack of solar installations in and near some of these states’ cities, major and small.

California has the most installed solar power in the U.S. but its solar-rich neighbors are lacking in their efforts to take advantage of the sun’s rays. Based on National Renewable Energy Laboratory (NREL) and the Department of Energy’s Energy Information Administration (EIA) these seven cities are among the top places in the U.S. that could benefit by adding more solar power into their energy mix.

NREL’s OpenPV Project is the most comprehensive resource showing where solar power has been installed throughout the country. Matching information available through the project with NREL’s Photovoltaic Solar Resource Map (above) and information available at EIA about each state’s renewable power sources, shows which cities have the most potential to increase their use of solar power.

However, no resource includes all solar installations in the U.S. and with the speed and ease of installing solar panels, these cities can catch up quickly with other places and the entire picture could be changed by 2011.

Flagstaff, Arizona. With 288 days of sunshine a year an elevation of 7,000 feet above sea level and relatively mild weather with January’s coldest nights averaging 16.5 degrees Fahrenheit and 82.2 degrees Fahrenheit in the heat of the summer, Flagstaff is an ideal city for photovoltaic power. According to OpenPV, Flagstaff has about 246 kilowatts of photovoltaics installed. In comparison, Phoenix, Arizona’s largest city has 7.7 megawatts installed. Flagstaff has an office of sustainability and its plan for expanding renewable energy is awaiting approval.

Carson City, Nevada. Carson City, Nevada’s capital city has about 87 kilowatts of solar installed. The city experiences an average of 266 days of sunshine a year. Carson City’s average temperatures are about 19 degrees Fahrenheit in the winter and 89 degrees Fahrenheit in the summer. It should be an ideal location for solar installations, but at this point the local government and other resources mention no solar installation project in or around the city. Energy guzzling Las Vegas and its surrounding Clark County gets the most solar power in Nevada, the county produces about 27.7 megawatts of the state’s 28.7 megawatts of solar power.

El Paso, Texas. Texas is known for being big, that’s great and all, but it’s also got a lot of great potential for solar power. The state is currently the U.S.’s largest producer of wind power. With more than 300 days of sun a year El Paso, known as Sun City and host of the Sun Bowl, ironically has no significant solar installations. The city is located on Texas’ western border and is firmly in the southwestern solar belt. In El Paso’s “Livable City Sustainability Plan” says the city is first focusing on reducing energy use, but plans to have 20% of its power supplied by local renewables by 2020.

Roswell, New Mexico. Home to Area 51 and aliens (perhaps), Roswell is also home to abundant sun with an average of 312 days a year and warmth with January lows hitting 41.2 degrees Fahrenheit and July highs hitting 83.7 degrees Fahrenheit, making it ideal for both photovoltaic solar power and solar thermal power. Roswell and the surrounding Chaves County have about 1 kilowatt of installed solar power, according to OpenPV. Other cities in New Mexico, like Santa Fe and Albuquerque take more advantage of the state’s solar resources.

Cedar City, Utah. Cedar City in Utah, known as Festival City USA, gets an average of 310 days of sunlight a year. The city doesn’t have any solar installations at this point. The city has produced “The Gateway to Clean Renewable Energy” but has no plans to build any installations at this point.

Pueblo, Colorado. Pueblo, in southern Colorado, has some solar power installed, about 6 kilowatts, according to OpenPV. But the city has about 330 days of sun a year and would be a great location for more solar installations. Even now the city is building a new solar-powered waste-water treatment plant. Pueblo’s not slacking in terms of sustainability however, the city’s making its sustainable mark by revitalizing Pueblo’s economy with a Vestas wind-turbine manufacturing plant.

Durango, Colorado. This southern Colorado mountain city doesn’t have any large-scale photovoltaic installations, according to OpenPV. However, on April 22, 2010, The Durango Herald said the DOE is considering installing solar on top of 2.5 million cubic yards of contaminated uranium mine tailings. Such an installation could provide up to 4.5 megawatts of power, which would power about 300 homes. The DOE is now checking out the project to determine its safety and feasibility. Durango has about 300 days of sun a year, and relatively moderate temperatures, making it ideal for photovoltaic installations. The city also has made numerous steps toward becoming sustainable in other ways including energy-efficient measures.

If you’re interested in solar learning more about solar installations in your region, check out NREL’s interactive OpenPV Visualization. If you know of a solar installation that’s not on the map, you can add it.