Personal investor. I started investing in clean energy stocks, mostly Chinese companies, in September 2011 which was after they had generally dropped 50-75% in value. I was purchasing CSIQ, DQ, JKS, MY, and YGE at what was close to their 52 week low price, but the only problem was they continued to drop another 15-20% in price before the end of 3Q2011. Fortunately, October 2011 has been a rebound month, and overall, I have gained back most of those losses (CSIQ and DQ are yet to recover). Now, with the European Sovereign Debt Crises in a temporary holding pattern, I am waiting for the 3rd quarter earnings reports for these companies. If the reports are good, then I think these stocks will do well.
Another watch point for these stocks will be the attempt to apply trade tariffs on sales of their products in USA. If the tariffs do not happen, that will be good news. But even if the tariffs do happen, I think these companies will continue to grow and be profitable from their sales within China (which apparently is very committed to clean, renewable energy) as well as around the world.
Other stocks of interest to me: ASYS and MNTA for a bit of diversification.