I don't think that Kyocera really derives that much of their revenue from their solar biz, percentage-wise.

Capstone makes little microturbine gensets usually run on natural gas (but not infrequently on landfill or digester gas, and they're hyper-efficient, so let's give them a pass.)

ECD is Uni-Solar, mostly, and some fuel cell and hydrogen storage, that's a pure play. Same for Evergreen Solar.

Magnetek makes inverters, I think a big part of their business is solar...

Ormat = turbines for geothermal generators. Growth business, some environmental complaints, but almost definitely a net winner.

Echelon is really more of a "smart grid" / distributed generation company, and while much of that is clean energy, it's certainly not necessarily so...

Maxwell technologies is an electronic components manufacturer, probably best known for their ultracapcitors, which could be a hybrid car enabling technology, work into wind power controls, etc., but they're mostly a plain-vanilla electronics component manufacturer there....really, same thing for American Power Conversion (perhaps best known for their desktop computer backup batteries, and International Rectifier.)

FCE and Plug Power are pure-play fuel cell companies, but Praxair is just an industrial gas supplier. Hydrogen is probably pretty incidental to them as compared with welding gases (and possibly medical gases - O2 and the like.) Same for Air Products...both are growing their H2 iz aggressively, but I don't know about calling htem clean energy companies.

I was a Ballard Power Systems investor twice across 3 years. The company has very interesting technology; however it is a very poor investment. There are a few reasons for this:

• It has been losing money for 10+ years, which means that the common stock keeps depreciating due to recapitalizations,
• Its technology requires a national infrastructure of hydrogen storage to be useful,
• some of the major automakers have been reluctant to work with a single fuel-cell provider, fearing vendor lockin, and
• hybrid technology engines have seized the industry momentum and popular imagination. All the investment dollars that might have gone to fuel cells are going to hybrids instead.

In short, don't put a dollar into Ballard if you can help it.

I like PBW. I invest in it myself. I wrote an article on investing in alternative energy at my blog site. Please check it out! Let me know what you think.