Editor's note: This article has been updated from Friday, Jan. 13,  to include Real Money columnist Bruce Kamich's charts and analyses. Prices have also been updated.

Solar energy is hot. Utility capacity is growing exponentially in the U.S. and abroad. By mid-century solar energy is expected to produce more than 15% of the world's electricity, up from 1% today.

Investors eager to tap into this growth phenomenon though must choose wisely. The growth can come from many different, largely small-cap companies marketing a variety of products and services. So there are no sure winners. This makes solar a much more wide open field than wind power, the second-fastest energy growth source, where the increases will come mostly from continuing to produce and install the same types of large wind turbine developments.

Some companies appear to have more promise than others, says The Street's Barry Rehfeld. Among them are SunPower (SPWR) - Get Report , First Solar (FSLR) - Get Report and, surprise, Tesla (TSLA) - Get Report .

Real Money's Kamich's also published his views on the trio Friday, Jan. 13. He sees a near-term recovery for First Solar, but says Tesla may need to recharge and a SunPower rally is somewhere over the rainbow.

Kamich says First Solar has gotten plenty of media attention, but it hasn't translated into investor enthusiasm until recently. FSLR had made a significant decline last year breaking below the lows of 2015.

That was last year. 2017 is a new year and we should save some positive thoughts for FSLR. Let's check the latest charts and indicators.

In this twelve-month daily bar chart of FSLR, below, we can see how prices were cut in half and then some more from March to November. Volume was heavier on some of the sharp declines signaling that traders and investors were voting with their feet. The slope of the 50-day moving average line has been negative since April but prices recently closed above the average line. The 200-day moving average turned down in early August and still has a negative slope. Volume was heavy for much of November as prices sunk to new lows. This heavier volume pattern could be considered "throw in the towel" selling.

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Kamich says Tesla's stock has rallied the past five weeks, notching a new high for the move up Friday. Despite a $50 rally, our indicators have not strengthened all that much, so we are reluctant to get too enthusiastic.

Let me show you the latest charts and indicators to explain my position.

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In this one-year daily bar chart of TSLA, above, we can see prices quickly rallied above the 50-day and 200-day moving averages in December. The slope of the 50-day has turned positive. The On-Balance-Volume (OBV) line has turned up modestly the past four weeks and shows there is some increase in aggressive buying. There is a small bearish divergence between the higher price highs in late December and early January and equal highs from the momentum study.

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SunPower may have stopped falling, says Kamich, but it doesn't look as if it has attracted serious buyers yet. It's sunny days are probably somewhere in the future. Over the rainbow perhaps?

In this one-year daily chart of SPWR, below, we can see a long decline. There is a runaway, or measuring, gap in August. Prices reached a low, but probably not a bottom, in November. There was some increase in volume at the November nadir, but not a really heavy pace to suggest "throw in the towel" dumping.

Prices recently crept above the 50-day simple moving average line, but the slope of the line is still pointed down. The 200-day moving average line is well above the market, and had a bearish slope all year.

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Rehfeld says SunPower and solar energy are virtually synonymous. It has long produced the most efficient PV panel in the world. That gives it an important edge in large scale developments and on many rooftops because buyers need less land or space to get all the energy they need. Also, with fewer panels needed, installation costs are lower too.

Its stock was making a spectacular recovery from the Great Recession until oil prices plummeted in 2014. Losing over 80% of its value since then to close Thursday at $7.31, the shares look like a bargain with investment in solar growing and, with that development, costs falling.

First Solar may be the choice for investors with a more conservative bent. It's the industry leader -- three times the size of SunPower -- and betting on the low-cost, thin-film PV. The company has been consistently profitable and its shares have not been beaten down as badly -- nor had increased as much -- as those of SunPower.

It, too, is a bargain. Closing at $34.87 Thursday, it is trading at a price to earnings multiple of just over 7. That's a little more than a quarter of the multiple for the S&P 500 index. It's trading midday Tuesday at $35.60.

Tesla, of course, is known as an electric car company, but it is in two solar businesses, one extremely important. Two months ago, it acquired SolarCity, the largest leaser and installer of solar panel systems for homes and business. Indeed, thanks to investments by Tesla and SolarCity, solar power is the source of all the electricity on an island in the American Samoa.

But Tesla's ace in the hole is its lithium ion battery business. Last week, Tesla began production in its Nevada battery gigafactory. This puts Tesla in a position to be one of the dominate players in producing storage capacity for solar energy.

Tesla's shares, at $235.76 Tuesday, have languished since oil prices collapsed. However, with three solar-complementary revenue drivers (i.e. the factory is run on solar energy exclusively) Tesla's prospects for its stock to finally take another leap up have never been more promising.

Rehfeld says Solar has a variety of competing technologies. There is the photovoltaic (PV or light) and thermal (heat) solar power. Among companies that produce PV equipment, some may produce the more expensive and more efficient rigid solar panels, while other may make the less costly and less efficient thin-film collectors.

They may also do business different ways. Companies may excel at selling solar through distributed channels (i.e., retail for rooftop installations) rather than centralized outlets (i.e. solar farms or fields for utilities). They may, in fact, lease solar equipment instead of selling it. Businesses that produce batteries to store solar power, for use when the sun doesn't shine, are also important to the success of solar energy.

Whatever investors do, solar energy and these three stocks deserve their attention.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.