Morocco has officially switched on Noor I, part of a massive solar thermal power plant in the Sahara Desert that will light up 1 million-plus Moroccan homes using 500,000 crescent-shaped solar mirrors visible from space.

Located near the town of Ouarzazate, the new installation covers thousands of acres and is expected to grow to 6,000 acres by 2018 — larger than the country’s capital city of Rabat — making it the largest concentrated solar power plant in the world, according to Gizmodo and NASA.

Solar thermal power plants, also called concentrated solar power plants, use the sun’s energy to heat water and produce steam that spins energy-generating turbines.

Noor I is creating 160 megawatts of power, making it, in its first phase, already one of the world’s largest solar thermal power plants. If the next phases — Noor II and Noor III — are completed as planned in 2020, the plant is expected to generate 580 megawatts.

Solar thermal power plants capture the sun’s energy as heat, then convert water to steam and turn turbines, NPR reported. The plant is similar to large-scale plants located in the Mohave Desert in the U.S.

A major advantage of solar thermal power (also called concentrated solar power or concentrating solar power) is its ability to store the heat to make energy at night. Unlike photovoltaic systems, thermal systems don’t suddenly produce less when a cloud passes over.

Noor will become the largest concentrated solar power plant in the world,  according to NASA. Almost half of Morocco’s energy is expected to come from renewables, and about a third of that will be from solar.

Morocco imports 97 percent of its energy, according to the World Bank, which helped fund the Noor power plant. Investing in renewable energy will make Morocco less reliant on those imports and reduce the country’s long-term carbon emissions by millions of tons.

Originally, the plan was to deliver the electricity generated by Noor to Europe but several partners pulled out, according to Gizmodo. The African Development Bank and Moroccan government intervened to save the project, and now it’s being used to meet Morocco’s own power needs.

The budget for Phase 1 of the project was $652 million according to data from the Moroccan Ministry of Energy, MiddleEastMonitor reported.

Here’s how the solar thermal power plant produces energy, according to Gizmodo: its crescent-shaped solar mirrors follow the sun all day to soak up sunlight. Each 40-foot-tall mirror focuses light on a steel pipe that carries a synthetic thermal oil solution. The oil in the pipes can reach 740 degrees fahrenheit, and that’s what’s used to create electricity. The heat is used to create steam which drives turbines. The hot oil can be stored to create energy at night.

The technology is more expensive and less widely used than photovoltaic solar panels you might see on residential roofs in many parts of Africa, but is well suited for harnessing the desert’s solar energy, according to TheGuardian.

“The potential for solar power from the desert has been known for decades. In the days after the Chernobyl nuclear accident in 1986, the German particle physicist, Gerhard Knies, calculated that the world’s deserts receive enough energy in a few hours to provide for humanity’s power needs for a whole year.

The challenge though, has been capturing that energy and transporting it to the population centres where it is required.”