If you read solar news, you know U.S. solar projects have reached whopping proportions.

The trend goes beyond individual records: The sheer number of those giant projects is increasing as well. The tally of projects larger than 120 megawatts (AC) going into service in the U.S. will jump from 11 in 2019 to 32 in 2021, according to data from Wood Mackenzie Power & Renewables.

Sean Kiernan, senior vice president of development at 8minute Solar Energy, remembers when “large” meant more than 20 megawatts. The biggest projects now under development in the U.S. slide just under 700 megawatts (DC).

“Clearly, we’re seeing in the market that...larger projects, where possible, will have some pretty clear benefits," said Kiernan.

Those benefits include economies of scale and higher production returns from development work. But the proliferation of huge projects has also sparked controversy in parts of the country. Conservation groups have warned that Gemini Solar, a partnership between Quinbrook Infrastructure Partners and Arevia Power that is the largest project currently under development in the U.S., could harm desert wildlife in the area.

U.S. Projects Larger Than 120 Megawatts (AC)

Wood Mackenzie Power & Renewables

The ability to scale projects up depends on the location. California and Texas, the two states with the most projects greater than 120 megawatts according to WoodMac, offer ample space and strong solar resource. In parts of the Northeast, achieving that scale is difficult, if not impossible.

“I’m impressed and amazed by some developers who have gone to some markets like PJM and have been able to do really large projects,” said Kiernan. “I know firsthand how incredibly difficult that would be.”

So will project sizes continue to grow, including after the federal Investment Tax Credit phases down? It remains to be seen. The “elusive 1.0-gigawatt (DC) project” may arrive within this decade, said Colin Smith, a senior solar analyst at WoodMac.

Are economies of scale overrated?

At the same time, many in the industry point to quantity rather than size as a key indicator of success.

"The reality is that...project[s] at 100 megawatts or higher all have the same economy of scale," said Benoit Allehaut, managing director of the clean energy infrastructure group at investment firm Capital Dynamics, which claims to own seven of the 20 largest U.S. solar projects.

"Solar is very, very modular," Allehaut said. "If we want to reach 50 percent and, down the line, 100 percent renewable energy, there will be a need for a very...large number of assets.”

Though developers size projects to meet demand and capture the advantageous economics, in the end, the size of the project may also be built for wow factor. Most states with renewable portfolio standards plan to meet them through a combination of distributed generation, large-scale projects and efficiency measures.

“To me, bigger projects are ‘bragawatts,’" said WoodMac's Smith. "The important factor is what is going to drive more solar in the U.S. It’s much more important and noteworthy to see fifteen 100-megawatt projects sign power-purchase agreements in a given state than it is to see [one] 1,000-megawatt project."

“The area where size does matter and bigger is better is energy storage," Smith added. "We are not far away from hearing about not being able to add more solar unless more storage is added to the grid as well.”