That isn't easy. Let me explain why. While there are many companies manufacturing solar panels and related equipment, most of the manufacturers are divisions of much larger companies. You can participate in Solar, for instance, with shares of BP but the solar portion will be tiny compared to the oil portion of your investment.
One way to start building a list of candidates is to examine the portfolios of the exchange traded funds that are focused on "green" investing. Here's a link to an article on the "Seeking Alpha" website that lists the major green funds:
http://seekingalpha.com/article/36094-the-green-investor-choosing-an-alternative-energy-etf
Scott
