One smart way to make money in the markets is to buy stocks that are growing fast and still have a huge addressable-market opportunity ahead of them. 

So which stocks fit that mold today? We asked a team of Motley Fool contributors to weigh in, and they called out Alibaba Group (NYSE:BABA)NextEra Energy Partners LP (NYSE:NEP), and Tucows (NASDAQ:TCX)

COins stacked to look like rocket ship

Image source: Getty Images.

Open, sesame!

Anders Bylund (Alibaba Group): Chinese e-commerce titan Alibaba is already a huge business. With a $480 billion market cap and $38 billion in annual revenues, this is no hungry little upstart.

None of that is stopping Alibaba from behaving like a hungry little upstart, though.

BABA Revenue (TTM) Chart

BABA revenue (TTM) data by YCharts.

Alibaba's revenues have nearly tripled over the last three years while free cash flows have more than doubled. The company extracts more than $0.50 of free cash flow from every incoming revenue dollar, making it one of the most efficient cash machines I know.

And this is indeed just the beginning. These fantastic results were achieved from an almost entirely Chinese customer base, though many of Alibaba's buyers end up exporting the goods abroad through channels such as (NASDAQ:AMZN) and eBay (NASDAQ:EBAY). The next time you're shopping for low-cost trinkets, electronics, or sporting goods via eBay's or Amazon's third-party seller programs, there's a good chance that your order will pass through Alibaba's shopping and shipping systems at some point.

The next step will include setting up direct retailing operations in places like Europe and North America, placing Alibaba closer to the end of the e-commerce pipeline and allowing it to grab a larger share of the profits from each item sold. The company managed roughly $500 billion of gross merchandise volume (GMV) last year, but that's still just a 15% share of the Chinese retail market and an even smaller slice of the global opportunity. Chairman Jack Ma hopes to double Alibaba's GMV to a cool $1 trillion by the year 2020.

So Alibaba is staring down a huge runway for further growth, starting from an already huge business. You can buy into this exciting growth story at very reasonable valuation ratios such as 22.5 times forward earnings or 8.5 times Alibaba's book value. I'm already a happy shareholder, watching my Alibaba investment double its value in less than four years.

You should probably join me. This company is going places.

A strong first half for this renewable energy leader

Maxx Chatsko (NextEra Energy Partners LP): On the one hand, NextEra Energy Partners is a renewable energy yieldco -- and most companies in that bucket have struggled mightily in the last several years. On the other hand, its parent is NextEra Energy -- the world's largest utility and the undisputed king of renewable energy deployments. The latter argument wins out as far as investors are concerned.

NextEra Energy Partners has been by far the best performer in its peer group since its IPO. It also just delivered a strong first half of 2018. Compared to the first half of last year, operating income jumped 105% while net income soared by several hundred percent following a healthy benefit from lower corporate tax rates. Cash available for distribution after debt payments increased 37% in the second quarter of 2018 compared to the year-ago period. 

As good as the results have been, this high-growth stock could just be getting started. NextEra Energy Partners just sold off all of its Canadian assets for $573 million, plus another $673 million in debt that the acquirer will assume. That creates a considerable amount of financial flexibility to pursue the company's all-American renewable energy strategy -- and the timing is perfect.

That's because parent NextEra Energy expects to grow its renewable energy backlog from 28,000 megawatts at the end of 2017 to an astounding 40,000 megawatts by 2020. The partnership will have first dibs on acquiring any of those assets made available for sale, which will provide the potential for incredible growth for years to come.

A winning formula

Brian Feroldi (Tucows): Tucows isn't a well-known name among U.S. investors, which is a shame. Few companies can match the return that this company has provided to its investors over the last decade.

TCX Chart

TCX data by YCharts.

Tucows' phenomenal stock price movement is attributable to steady growth in its core business -- internet-domain registration services -- as well as growth in its discount mobile-phone service in the U.S. and the launch of a home fiber internet business.

The company's growth plan from here is quite straightforward: Management will funnel the predictable profits earned in its internet-domain registration business to grow its Ting mobile and Ting internet services.

The potential ahead for both of these businesses is truly massive. Tucows' Ting mobile business only serves about 280,000 subscribers, which rounds to about a 0.1% market share in the U.S.

It's a similar story for the Ting internet business. The company operates in just three small U.S. cities at the moment, with a fourth planned soon. There's almost unlimited room left for expansion in this business segment, too. 

Overall, Tucows' operating history should give investors confidence that it has stumbled upon a winning formula that clearly generates great returns for forward-thinking shareholders. With ample room left for growth, Tucows is a business that I could see myself holding for years to come.