While Americans celebrated U.S. history on the Fourth of July yesterday, a company in Spain celebrated an historic moment for the solar industry: Torresol’s 19.9 megawatt (MW) concentrating solar power plant became the first ever to generate uninterrupted electricity for 24 hours straight.

The plant uses a Power Tower design which features a field of 2,650 mirrors that concentrate sunlight onto a boiler in a central receiver tower. The plant also utilizes molten salt as a heat transfer fluid that allows it to generate electricity when there’s no sunlight.