The US Department of Energy (DoE) on Thursday announced an ambitious new target to cut the cost of solar energy by 60% this decade, a step it calls “essential” to accelerating deployment and achieving President Joe Biden’s goal of a carbon-free electric grid by 2035.

To reach that goal in the next 15 years, hundreds of gigawatts of solar energy need to be installed at a rate up to five times faster than it is now, according to DoE, which forecasts that modules could generate between 30% and 50% of a US electricity supply devoid of fossil fuels.