But there is opportunity in making a solar-fired kiln (mentioned in the article), and produce pure silicon from sand and carbon. The article mentions 1500C, but

But there is opportunity in making a solar-fired kiln (mentioned in the article), and produce pure silicon from sand and carbon. The article mentions 1500C, but I'm not sure if 1800C is attainable with the method. Also, (lack of) vacuum might be a problem.