First Solar (FSLR), a new member of IBD Leaderboard, has rallied sharply in recent months. Today's column introduces a double butterfly options trade in First Solar stock.X After watching the daily recaps on IBD Live this past week, my eyes turned to First Solar stock. Clearly it's a strong name in a previously weak sector. According to IBD Stock Checkup, the utility-scale solar infrastructure firm hosts a mediocre 72 Relative Strength Rating. However, the Composite Rating is 93 on a scale of 1 to 99, tops ...