Jim Cramer advised against buying the solar company's stock on margin after a caller mentioned purchasing at $275. The stock recently traded around $241. A bullish thesis from a retail investor highlighted its forward P/E ratio of 10.43. The broader cleantech sector faces headwinds from weak demand, policy uncertainty, and unfavorable subsidy shifts, capping near-term upside. Despite this, the stock gained on a day the broader market dipped.