If you haven't been paying attention to the solar energy industry in China over the last couple years, perhaps now is the time to sit up and take notice - and maybe the time to buy in, as well.

In December of 2005, China Sunergy (also called Suntech and listed as STP) became the first US-listed solar energy company out of China and for over a year was the only such company listed on an American exchange. But the number of solar technology companies listed on U.S. stock exchanges is growing at the moment. Last year saw four Chinese firms show up through IPO's in the US or the UK: Canadian Solar, Inc. (CSIQ) in November on the NASDAQ; Renesola Ltd. (SOLA.L.) in August on London's AIM exchange; Solarfun Power Holdings (SOLF) in December on the NASDAQ; and Trina Solar Limited (TSL) in December on the NYSE.

The most recent arrival to the solar energy IPO scene is LDK Solar, which debuted on Friday on the NYSE and was up not quite 12% at the end of trading. Compare that to the 51% that China Sunergy was up on its first day back in 2005 and you could be a little disappointed. Still the offering raised $469 million for LDK.

Leor Pantilat recently pointed out some good reasons why Chinese companies in the solar power industry are choosing to list their IPO's in the US instead of Shanghai or Hong Kong. The fact that they are lsiting themselves here instead of in China gives US investors an easy path to dip into the Chinese investment scene.

Next in line? Yingli Solar, possibly as soon as later this month; and CEEG to follow probably before the year is out.

Why pay attention now? Engaging China's Geoff Nairn pointed out recently that China was fast becoming "a key player in the solar power industry" for a number of reasons. But financial analysts disagree about whether growth in this sector of the Chinese economic is about to falter or whether it is just experiencing a minor slump. Some of the leading companies are seeing profits come in at less than expected during the Q1. Is it time to bail or is it time to buy in? We'll look at that question over the next few weeks...