While solar power is nothing new, maintaining solar power when the sun doesn't shine is another approach that is being implemented in both Arizona and California.

Recently, Flagstaff, Ariz. residents woke up to an unexpected snowfall, which resulted in thousands turning up their electric heating.  In order to meet the demands of the morning peak, Arizona Public Service used the previous afternoon's sunshine, The New York Times reports.

A new closely monitored solar project called Solana is underway. So how does it work?

"The energy is gathered in a three-square-mile patch of desert bulldozed flat near Gila Bend, about 50 miles southwest of Phoenix. A sprawling network of parabolic mirrors focuses the sun's energy on black-painted pipes, which carry the heat to huge tanks of molten salt. When the sun has set, the plant can draw heat back out of the molten salt to continue making steam and electricity."

"The emerging technology is one way that the utility industry is trying to make electricity from the sun available even when it is not shining, overcoming one of the major shortcomings of solar power," the NY Times adds.

Due to the "major shortcomings of solar power," regulators are zeroing in on the issue. In California, the Public Utilities Commission approved a rule last week that will require the state's three big investor-owned utilities and other electric industry players to install storage by 2024.

"The impetus to require storage is definitely inspired by the success of solar," said Robert Gibson, vice president of the Solar Electric Power Association, a nonprofit educational group. "Hopefully the California initiative is going to kick-start this and bring down costs," he said. Battery makers have predicted progress, he said, adding that cost-effective storage "has always been a few years out."

While many associate Arizona and California with an abundance of sunshine that clearly isn't always the case, and regular solar panels just aren't cutting it.

Arizona Public Service's faces its biggest obstacle in the early morning, "before the sun is high enough to hit conventional solar panels, the kind installed on rooftops to turn sunlight into electric current."

In addition to Arizona, California is increasingly facing the same problem in the evening, "when the sun is too low for the panels to work, just as thousands of people are returning home and workplaces are still humming."

While solar panels can help utilities meet afternoon peaks, they are falling short on the morning or evening ones; "by 6 p.m., panels are producing only about half their maximum, even if they are installed on tracking devices that tilt the panels to follow the sun across the sky."

"Solana is a $2-billion project built with a $1.45 billion loan guarantee from the Department of Energy. Close behind is the Ivanpah project in California. It uses a field of mirrors the size of garage doors, mounted on thousands of pillars, to focus the sun's light on a tower with a tank painted black, the NY Times adds. "Engineers say that design could incorporate storage efficiently, because the tank reaches very high temperatures. That plant will enter commercial operation by the end of October."

Mexico has also come into the solar energy arena.

The country that is "poised to allow foreign oil extraction for the first time in 75 years," is finding that its abundant natural resources also appeal to investors in a much cleaner energy: sunshine," Bloomberg reports.

First Solar Inc. (FSLR) of the U.S. has bought its first projects in Mexico, while more than a dozen other developers including Germany's Saferay GmbH and Spain's Grupotec Tecnologia Solar SL own licenses there.

A top 10 oil producer, Mexico has cleaner plans on the horizon. The country anticipates it will generate 35 percent of its power from clean sources by 2026, up from less than 15 percent now, to curb emissions and diversify its energy mix.

"A global surplus of solar panels has made them cheaper, while the costly oil-fired plants common in areas such as Durango, Sonora and southern Baja California make solar a competitive option."

With that said it's important to note that like Arizona and California, Mexico may also run into the same solar energy issue and need to tap into solar power when the sun isn't shining. Who knows, maybe Mexico might use the Solana solar project as a model down the road.