Panasonic (NASDAQOTH: PCRFY) and Enphase Energy (NASDAQ: ENPH) announced a partnership that will bring AC (alternating current) solar panels to the U.S. market by the summer. Enphase's micro-inverters will be attached to Panasonic's high-efficiency HIT solar panels.The move follows an industry trend to install module-level electronics -- micro-inverters or power optimizers on each solar panel -- at the factory level.