The major publicly traded solar inverter companies are Power-One (NASD:PWER), Satcon (NASD:SATC), SMA Solar (OTC:SMTGF), Siemens (NYSE:SI), Advanced Energy Industries (NASD:AEIS), Schneider Electric (OTC:SBGSF) and upstart Enphase Energy (NASD:ENPH). Over the last year the industry has faced eroding margins and an increasingly competitive environment. This parallels the problems of solar manufacturers: the industry has too much capacity for a market that is not growing as fast as many expected.