A Department of Energy effort to lower the cost of solar power has hit a key goal thee years early, officials said Tuesday.

The agency is also set to expand the goals of its SunShot Initiative and pump new funding into reducing costs and expanding energy storage, the department announced.

The price of electricity generated by utility-scale solar photovoltaic systems fell to $0.06 per kilowatt hour this year, achieving a 2020 goal of the SunShot program three years early. Prices for residential and commercial systems are 86 percent and 89 percent toward achieving their price goals, the Energy Department reported.

Given the reduction in prices, the agency said it will continue its work to cut costs further and fund projects that "will focus on a broader scope of Administration priorities," including electric grid reliability and energy storage.

"With the impressive decline in solar prices, it is time to address additional emerging challenges," said Daniel Simmons, the agency's acting assistant secretary for energy efficiency and renewable energy.

"As we look to the future, DOE will focus new solar R&D on the secretary's priorities, which include strengthening the reliability and resilience of the electric grid while integrating solar energy."

The Energy Department said it will spend $82 million to research energy storage and grid reliability technologies for solar power.

Solar supplies about 1.5 percent of U.S. electricity, but it's one of the fastest-growing sources of power in the country. Companies installed 2,387 megawatts of solar panels in the second quarter of 2017, and solar power capacity grew by 8 percent.

Updated at 2:16 p.m.