If investing in individual stocks makes you too nervous, then exchange-traded funds can be just the answer you're looking for. ETFs give you exposure to a diversified portfolio of stocks, and you can find both broad-based and narrowly focused ETFs to suit just about any investor's wishes.

The stock market's gotten off to a good start in 2020, but some ETFs are leaving the broader market in the dust. In particular, the following three ETFs have given their shareholders strong returns so far this year, and many think they could just be getting started. Below, we'll look more closely at these three ETFs to see what makes them tick.

 Exchange-Traded Fund

Focus Area

Year-to-Date Return

Aberdeen Standard Physical Palladium (NYSEMKT:PALL)

Palladium

26%

Invesco Solar (NYSEMKT:TAN)

Solar energy stocks

22%

Global X Lithium (NYSEMKT:LIT)

Lithium and battery storage stocks

21%

Data source: Fund companies.

All that glitters is not gold

When investors think about precious metals, they usually concentrate on gold and silver. But lately, palladium -- an obscure metal used in automobile catalytic converters -- has taken off. Fetching less than $200 per ounce back in the early 2000s, palladium climbed to nearly $2,600 per ounce in January before falling back slightly. That's up considerably even from the level of just under $2,000 per ounce from late December.

The Aberdeen palladium ETF owns physical palladium, with each share representing a little over 0.094 ounces of the precious metal. With the challenges involved in owning physical bullion, many investors find the ETF a lot easier to buy and sell. The ETF's track record in matching up to the changing price of palladium bullion is excellent, with many finding the 0.60% expense ratio well worth it.

Here comes the sun

Invesco Solar owns shares of companies in the solar and alternative energy space. You'll find a wide range of companies among the ETF's holdings, including not only solar panel manufacturers but also some of the ancillary businesses that help users build out complete solar power systems.

Set of 20 solar panels on a roof, with the sun shining above it.

Image source: Getty Images.

So far in 2020, much of the big gain in the solar ETF has come from makers of solar inverters and power optimization equipment. Companies like Enphase Energy and SolarEdge Technologies specialize in taking the power from solar panels and transforming it for use in homes, and Enphase, in particular, has seen huge gains of nearly 60% so far this year. With interest in renewable energy on the increase, it's not surprising to see Invesco Solar near the top of the list of ETF performers so far in 2020.

Get a charge out of this

On a slightly related note, lithium stocks have been popular lately as well. With rising attention going to battery technology, companies engaged in producing the lithium necessary for top-capacity batteries as well as those actually concentrating on building those batteries have gotten a lot of interest in 2020.

Among Global X Lithium's top holdings, Tesla is the best known, with its lithium-based batteries not only powering its electric vehicles but also poised for us in broader solar power applications. Tesla's massive share price gains have helped the ETF's overall returns immensely. Yet you'll also find good performance from industry players like lithium chemical producer Albemarle. Even as traditional energy stocks have sunk precipitously, these stocks look poised for a long run ahead.

Put these ETFs to work

Often, top-performing ETFs have already seen their biggest gains, and buying them near the top can be dangerous. But in this case, all three of these funds have the potential for even further greatness. That makes them worth a close examination for those looking to take advantage for the rest of 2020 and beyond.