Some companies are obviously great investments -- in hindsight. Sure, we should have bought Starbucks at its IPO and earned amazing returns over the years. Yet for every stock out there screaming "buy me," others simply give us a nudge and a nod. How can we tell tomorrow's obviously great investments from the thousands of pretenders?

The stars' walk of fame
On Motley Fool CAPS, these opportunities can be found among our four-star stocks. In CAPS' proprietary ratings system, they rank higher than most of the other 5,600 stocks in the CAPS universe, but they're just shy of superstardom. While all the attention might be focused on their five-star peers, we can sift through CAPS to find some four-star firms approaching greatness:

  • Alliance Data Systems (NYSE: ADS)
  • Broadcom (Nasdaq: BRCM)
  • Gold Fields (NYSE: GFI)
  • Kodiak Oil & Gas (AMEX: KOG)
  • ReneSola (NYSE: SOL)

Some of these names might surprise you. As its last quarterly report indicates, telecom semiconductor provider Broadcom has been able to dodge the meltdown in the field that seems to be sinking most of its competitors. Almost great? But even familiar names can still offer some of the best opportunities. Perhaps we've just forgotten the potential they still hold. The 100,000 investors over at CAPS chose these companies as less obvious sources for tomorrow's great buys, so let's see why they might merit your attention.

A hot topic
With all the advances that solar stocks have made in the past few years, some companies have floated to the top like cream on milk and are on their way to becoming household names. First Solar (Nasdaq: FSLR), Suntech Power (NYSE: STP), and SunPower are just a few of the more common ones out there.

ReneSola may end up becoming one of them, too. Amid the resurgence of a number of solar names, this Chinese solar wafer manufacturing giant is making a comeback bid after a U.S. IPO earlier this year that was generally considered a flop. Mark it down to poor timing. Had it offered last year when solar stocks were blazing hot -- the names above all doubled in price last year -- ReneSola might have caught fire, too. But it came onto the U.S. markets at a time when profits were being taken from solar stocks and the markets were more jittery than usual. It offered at $13 a share and fell as low as almost $7 a stub in the ensuing weeks.

Yet a series of manufacturing agreements, as well as guidance that calls for an increase in production to 310-320 megawatts from 300 megawatts, makes this low-cost wafer manufacturer with long-term supply agreements a possible sizzler in the future.

Investors like CAPS player tayfur see ReneSola -- as the supplier to the panel manufacturers -- winning, regardless of which other solar companies succeed:

With alternative energy solutions being aggressively sought due to the continuing painful rise in oil prices, [ReneSola] has an advantage of a low price advantage in its manufacturing process. Being a supplier of wafers to the solar panel industry, it succeeds regardless of the eventual winner in the solar panel manufacturing competition. To top it off, It just signed 6 year contracts to supply its customers with its wafers, ensuring a future revenue stream.

Even investors like synergize, who found ReneSola on the basis of technical models, like some of the fundamental underpinnings of this solar supplier:

The stock hit its second bottom last 3/20/2008 at near $7 and since then it's been up and actually doubled. It closed at $15.30 yesterday 4/17/2008. Its first bottom was last 3/10/2008. I thought that this was a double bottom or "W" formation which is a bullish indicator. Yesterday, it announced that the company is increasing its previously issued full year production output and revenue guidance for 2008... I actually picked this stock solely for technical reasons before I found out the news. So I felt very good with my pick.

A great opportunity for you
You've heard directly from CAPS investors on ReneSola, but do you agree? Are these four-star stocks still investment-grade material? On Motley Fool CAPS, you can give your input, which can ultimately influence how they're rated. Outperform or underperform, near-term or well in the future, your opinion counts.

Sign up today for Motley Fool CAPS -- it's completely free. Let's hear what you have to say about the great (and almost-great) companies that interest you.

Suntech Power is a Motley Fool Rule Breakers recommendation. See what other burning stocks are beating the market with a 30-day free trial subscription.

Fool contributor Rich Duprey does not have a financial position in any of the stocks mentioned in this article. You can see his holdings here. The Motley Fool owns shares of Starbucks, which is a Stock Advisor and an Inside Value pick. The Fool has a disclosure policy.