U.S. solar is laying claim to having “reshaped the energy conversation” and aiming to “dominate in the 2020s”, after the latest data from the Solar Energy Industries Association (SEIA) and Wood Mackenzie Power & Renewables showed the industry exceeding two million installations earlier in 2019, a year later than analysts originally predicted.

“The milestone comes just three years after the industry completed its millionth installation, a feat that took 40 years to achieve,” reports Greentech Media, a WoodMac publication. “Wood Mackenzie analysts expect the U.S. to crack the three million mark in 2021 and four million in 2023.”

“The rapid growth in the solar industry has completely reshaped the energy conversation in this country,” said SEIA President and CEO Abigail Ross Hopper. “This US$17-billion industry is on track to double again in five years, and we believe that the 2020s will be the decade that solar becomes the dominant new form of energy generation.”

Much of the growth to date has occurred in a limited number of state markets, but Wood Mackenzie says things are starting to open up elsewhere. “California represented 51% of the first million installations but accounted for 43% of the second million,” the company notes in its own summary of the report. “This is in large part due to a growing residential sector that is rapidly diversifying across state markets. South Carolina, for instance, was an emerging market in 2016 with 1,160 cumulative installations. Today, the state is home to more than 18,000 solar systems and is expected to add 22,000 systems over the next five years.”

As of this year, the country’s five leading solar states were California with 972,647, Arizona with 138,142, New York with 115,019, New Jersey with 105,453, and Massachusetts 92,076. As recently as 2010, California was the leading solar state—with only about 74,000 total installations. The report lists Texas, Utah, Florida, Rhode Island, and Maryland as states looking ahead to rapid solar growth.

“For all its momentum, the U.S. solar market has not been without its challenges,” Greentech notes. “ It reached two million installations a year later than analysts initially predicted, largely due to a drop in residential installations stemming from the decline of SolarCity/Tesla.”

Between 2016 and 2017, residential solar installations fell 15%, but Tesla’s share plummeted from 650 to 352 megawatts, Greentech recalls. “This was a significant drag on hitting the two-million-system mark, since residential systems make up 96% of a tally that counts the smallest rooftop PV array on equal weight with the biggest solar farm.” But Tesla’s pullback eventually opened space for other installers to pick up the slack.

The analysts said import tariffs on solar equipment had only a “negligible” impact on the industry, the publication adds.

“The residential sector has become much more diverse in terms of actual companies involved over the last three years,” said Wood Mackenzie Senior Solar Analyst Michelle Davis. “Tesla having a smaller share has meant that in the last couple quarters, as the market has recovered, other companies have picked up that market share.”