One analyst covering the solar-inverter maker $Enphase Energy(ENPH)$ believes it is time for investors to grasp at a “falling knife.” It sounds like a bad idea, but it might not be as dangerous as it sounds.Monday, Raymond James analyst Pavel Molchanov upgraded shares of $Enphase Energy(ENPH)$ to Buy from Hold. He says the price could rise to $225 a share, while he didn’t have a price target when he rated the stock at Hold.The bullish call lifted Enphase stock by about 1.4% to $186.19 in premarket trading on Monday. Futures on the S&P 500SPX +0.89% and Nasdaq CompositeCOMP +0.39% were both down about 0.1%.“We are turning positive on Enphase for the first time since 2013, i.e., ancient history by