Solar power company First Solar (FSLR) late Thursday badly missed expectations for the first quarter. FSLR stock fell in extended trading. X The Tempe, Ariz.-based company earned 40 cents a share on sales of $548 million in the March quarter. However, analysts polled by FactSet had expected earnings of 99 cents a share on sales of $714 million. In the year-earlier period, First Solar lost 41 cents a share on sales of $367 million. Meanwhile, the company kept its full-year outlook unchanged. First Solar predicts 2023 earnings of $7.50 a share on sales of $3.5 billion. That's based on the…