Invesco Solar ETF(AMEX:TAN)

TAN offers a unique take on renewable energy, holding a concentrated portfolio of companies involved in the solar energy industry, thus cutting out much of the broader renewable energy market. The funds selection universe begins with global solar energy companies of all caps including all solar technologies (crystalline and thin-film photovoltaic solar and solar thermal), the entire value chain (raw materials, installers, to financing), and related solar equipment (power inverters and encapsulates).These eligible companies are then categorized into two groups: pure-play or medium-play stocks. Pure-play companies consider solar industry as their primary business wherein they generate more than two-thirds of their revenue from. Medium-play companies cover those with multiple business industries but still are generating more than one-third of their revenue from solar related business. The funds weighting scheme attempts to boost exposure to pure-play companies and therefore underweights the medium-play group. Index constituents are rebalanced quarterly.