The cost of installing solar energy in the United States is down more than 50 percent since the start of a federal support program, the Energy Department said.

The federal government is supporting solar development through its SunShot initiative, which aims to make the renewable technology competitive. The program aims to move solar power capacity from less than 1 percent of the national electricity supply to 14 percent by 2020.

In a progress review, the Energy Department said it was about 70 percent on its way to reaching its goals. Solar power accounts for about 1 percent of the total electricity consumed in the United States, but represented 30 percent of the new power generation brought online last year.

Energy Secretary Ernest Moniz said that, under the program, solar power is becoming an integral part of the nation's grid.

"The U.S. has over 10 times more solar installed today compared to 2011 when the SunShot Initiative was first launched, and the overall costs of solar have dropped by 65 percent," he said in a statement.

Among the challenges identified in a study series, the Energy Department said integrating solar power into the grid is complex because, in order to maintain an effective market balance, utility system operators would need to favor one source of supply over the other. That could reduce the value and competitiveness of solar power.

For homeowners, meanwhile, federal studies find the technology may still be out of reach. The costs for consumers, however, could go down by up to 60 percent if the industry adopted finance methods that were similar to buying an expensive appliance or installing a new roof.

One of the main challenges outlined in an April report from the Energy Department is how to incorporate small-scale projects like rooftop solar panels into the grid.

Nevertheless, an April report from the International Energy Agency found new electricity generated from solar power saw its largest growth rate in the Americas than in other major economic regions.