I don't know about you, but I'm starting to forget what life was like before the Internet.

I can't even remember the last time I rented a movie at my local movie store instead of just logging onto Netflix or looked up a stock quote in a newspaper instead of on Yahoo! Finance.

In a lot of ways, that's sad. But it's also incredible to think that a technology that evolved out of the U.S. government's reaction to the Soviet Union's launching of Sputnik has come to dominate our lives.

Even more incredible ...
Investors who foresaw how profoundly the Internet would change our world have been able to make an absolute fortune off it.

Take those who understood the potential of e-commerce, for example. Most people scoffed at the idea of buying retail goods "online," but early investors in eBay and Amazon.com have grown their money by as much as 525% and 3,645%, respectively.

Needless to say, the Internet revolution turned out to be an unprecedented source of wealth creation. That's why I was blown away when I read that a well-respected venture capitalist now sees a megatrend on the horizon that he says could be ...

"Bigger than the Internet by an order of magnitude"
In case you're unaware, an order of magnitude is a multiple of 10.

That's right ... venture capitalist Ray Lane recently told The Wall Street Journal that he has found something he thinks could be 10 times as big as the Internet.

And he would know. After all, he was also an early backer of Internet companies such as Google, Amazon, and Netscape.

And he's not the only one who's taking notice
In a recent shareholder update, Fidelity Magellan manager Harry Lange outlined several reasons why his fund has begun to focus more on cleantech in general and on solar energy in particular.

  • Technological advancements and greater economies of scale are making it cheaper to produce electricity from solar energy.
  • Thanks to a declining cost curve and the rising cost of conventional fuels, solar energy is becoming more competitive in areas with high electricity costs.
  • Governments worldwide are providing tax incentives for both producers and consumers of solar energy.

The next great bull market?
All of these factors contributed to Wall Street's love affair with solar energy in 2007 ...

Stock

Gain in 2007

Suntech Power

142%

SunPower

251%

First Solar

792%

In fact, by the end of 2007, it looked as though Ray Lane was actually understating the case. But then 2008 hit, and the market began selling off steadily, before heading into an all-out tailspin. The solar sector was particularly hard-hit.

Stock

% Change in 2008

Akeena Solar (NASDAQ:AKNS)

(78%)

Evergreen Solar (NASDAQ:ESLR)

(82%)

Solarfun (NASDAQ:SOLF)

(85%)

Granted, much of this poor performance can be blamed on general market turmoil, massive hedge fund sell-offs, and ever-present recession fears, but it also serves as a reminder that just because you recognize a developing megatrend, that doesn't mean you're guaranteed to cash in on it.

In fact, more often than not, those who jump on board without doing their due diligence will end up losing a fortune.

Just look at the Internet
As anyone who was a 20-something slacker working in Silicon Valley in the late 1990s can tell you, the Internet spawned more big losers than big winners by an order of magnitude.

That's why at Motley Fool Rule Breakers, we've been doing plenty of research on cleantech and keeping a close eye on solar stocks in particular -- but you won't find us recommending every solar stock under the sun.

Among our recommendations, you will find a few carefully selected cleantech companies, including a proven leader in the solar industry and Huaneng Power (NYSE:HNP) -- a Chinese company taking the lead on forays into new clean-coal and nuclear power technologies.

We're also recommending that investors take advantage of major discounts on an alternative-energy exchange-traded fund that holds a wide range of companies involved in cleantech, including Energy Conversion Devices (NASDAQ:ENER), ReneSola (NYSE:SOL), and Yingli Green Energy (NYSE:YGE).

Granted, many of these stocks have been pounded into the ground, along with the rest of the solar sector and the market as a whole. But as the market begins its eventual recovery and the Obama administration begins to make good on its promise to make a massive investment in green energy, these stocks present a compelling profit opportunity.

Not to mention, they were handpicked using Motley Fool co-founder David Gardner's Rule Breakers criteria, which were designed to uncover top-notch growth stocks by finding companies that have:

  • Top-dog and first-mover status in an important, emerging industry.
  • Sustainable competitive advantages gained through business momentum, patent protection, visionary leadership, or inept competitors.
  • Great management with financial backing from smart investors and corporations.

Only time will tell whether this will lead us to gains 10 times greater than those generated by the Internet, but we're always on the lookout for the next millionaire-maker megatrend and the next great growth stock.

If you would like full access to all of our research and recommendations, including our top two picks for new money, we invite you to take a free 30-day guest pass to Rule Breakers. All you have to do is click here. There is no obligation to subscribe.

This article was first published March 24, 2008. It has been updated.

Austin Edwards looks forward to a world powered by sunshine. He owns shares of Google. Google, Suntech Power, and Huaneng Power are Motley Fool Rule Breakers picks. Amazon.com, eBay, and Netflix are Stock Advisor recommendations. eBay is also an Inside Value choice. Huaneng Power is also an Income Investor selection. And yes, even the Fool's disclosure policy sneered at that pun about "recommending every solar stock under the sun."