Solar capacity is gaining in urban areas across the U.S., according to a report released this week by Environment America Research & Policy Center and climate research organization the Frontier Group. 

The number of U.S. cities with more than 50 megawatts of solar installed jumped from eight in 2013 to 23 in 2018. During that same period, 79 percent of the 57 cities the organizations followed through six editions of the report more than doubled their installed solar capacity.   

Of the 69 cities surveyed in this year's report, Los Angeles claimed the top spot for total capacity installed, at 420 megawatts. Two other California cities, San Diego and San Jose, joined L.A. in the top 10 cities for total capacity.  

Source: Environment America Research & Policy Center, Frontier Group 

Though the results show that the cities with the most solar are largely clustered along the edges of the U.S., most regions contain a city with at least 10 to 20 megawatts of installed capacity. The top 10 cities for total solar capacity include those located in Hawaii and California, but also Indiana, Colorado and Texas. 

Unsurprisingly, states with good solar resources like Florida and California have one or more cities with over 50 megawatts installed. Cities in states with strong policy support for solar development, like New York City, also rank in the top 10 cities based on total solar installed. 

Honolulu, another city supported by strong state incentives, takes the top spot among cities in terms of solar capacity per capita, with 227 megawatts. The city also ranks fourth for total capacity installed.

Source: Environment America Research & Policy Center, Frontier Group 

When controlling for capacity, more states in the West have cities that rank in the top echelon with over 50 megawatts installed per person.

Despite the gains, researchers note there’s room for a great deal more solar in U.S. cities. 

A 2016 study from the National Renewable Energy Laboratory (NREL) lays out the high potential for cities to install a staggering amount of solar compared to current installations. Using buildings of all sizes, NREL found that the 128 cities it analyzed could cumulatively install over 1,000 gigawatts of solar to generate 39 percent of annual U.S. generation. 

The NREL authors also note that Los Angeles, the city with the highest solar installations per capita, has potential for 9 gigawatts of solar within its limits. That dwarfs its current installed capacity by over 20 times. And according to NREL study, 9 gigawatts would meet 60 percent of L.A.’s estimated electricity consumption.

With more cities and states committing to 100 percent renewable or carbon-free energy, concentrating renewables capacity near the highest demand could help meet those goals. But as states push those targets forward, they’ll also have to consider the costs.

Blanketing a city in solar — as California plans to do with its new-build home solar mandate — may not necessarily be the most economical way to power the masses. NREL’s study examined the solar capacity cities nationwide could technically absorb, but didn’t quantify the costs or technologies needed to integrate those resources.

“Most of the time, it’s cheaper and more cost-effective to install tens of megawatts outside the city limits and use existing transmission lines to send power to the city,” said Colin Smith, a senior solar analyst at Wood Mackenzie Power & Renewables.

According to Smith, since 2010, large front-of-the-meter systems have accounted for 61 percent of installed solar. He said cities and states will need to balance build-out of urban solar systems with large installations outside city limits.  

“As cities strive to hit 50 percent and 100 percent clean energy or carbon-free targets, a large portion of this power will need to come from wind and solar in urban and rural areas," he said. “That doesn't mean that cities don't have tremendous untapped potential for additional solar installations, but it does highlight the fact that there will need to be solar both on city rooftops and outside cities as well.”


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