When investors think defense, they think utility stocks.

The S&P 500's utility sector behaved anything but defensively in 2019, however. The Utilities Select Sector SPDR Fund (XLU) delivered a 25.9% total return last year - better than more than half the index's sectors, including the revamped, "growthier" communications sector and consumer discretionary stocks.

That's surely a pleasant surprise for utility-stock investors. Many enter the sector looking not for growth, but stability in down markets and the dependable dividends these companies can afford thanks to the often regulated nature of the utility business.

Like most of the market, utility stocks did get stretched as a result of their 2019 run. "The utility sector currently trades at a P/E of 19.3x, versus a 15-year historical average of 15.01x, which represents a 29% premium to the S&P 500," Michael Sheldon, executive director and CIO of financial planner RDM Financial Group, told Kiplinger in a December email.

While Sheldon is concerned about the sector's valuation, he's also quick to point out that many utility stocks have low beta - a measure of volatility. Thus, they're still providing more stability compared to the overall market.

Here are 10 of the best utility stocks to buy for 2020. This isn't your usual group of utilities, either. While some of these names should be expected to provide a traditional combination of dividend income and lower volatility, a few are set up for potential growth thanks to their connection to green-energy initiatives.

Algonquin Power and Utilities

Toronto-based Algonquin Power & Utilities (AQN, $14.18) held its 2019 Investor Day in early December. And the company had plenty of good news to discuss across meetings in both Toronto and New York.

As the utility stock heads into its next decade of