Here's a seemingly simple solar power fact*: the sun bathes Earth with enough energy in one hour (4.3 x 10²⁰ joules) to more than fill all of humanity's present energy use in a year (4.1 x 10²⁰ joules). So how to convert it? In the world of solar energy harvesting, there's a constant battle between cost and efficiency. On the one hand, complex and expensive triple-junction photovoltaic cells can turn more than 40 percent of the (specially concentrated) sunlight that falls on them into electricity. On the other, cheap, plastic solar cells under development convert less than 5 percent.

In between, ubiquitous photovoltaics—the multicrystalline silicon solar panels cropping up on rooftops across the country and, indeed, the world—struggle to balance the need for (relatively) easy manufacturing and low cost with technology to get the most electrons for your solar buck.

Chevron will tap sunlight to help it get more oil out of the ground in California. The company will partner with BrightSource Energy—a solar start-up that Chevron helps fund—to develop 29 megawatts of thermal power from the sun's rays.

The idea is simple (and ancient): use mirrors to concentrate the sun's rays onto a water tank, turning said water to steam. The steam can then be used to turn a turbine and produce electricity or, in this case, pumped down a well to loosen heavy oils.

The plant slated for the Coalinga Oil Field near Fresno will employ at least 3,000 mirrors to concentrate light on a more than 300-foot tower with water inside. Chevron hopes it will be fully operational by the end of next year. "The only problem we have is when it's cloudy," said Sergio Hoyos, a business developer at Chevron Technology Ventures, at the city council meeting last week where the plan was unveiled, according to Reuters.

If solar power is ever going to take off—and the world needs it to—photovoltaic cells will have to become a whole lot cheaper to produce.

Making solar cells from silicon, the most common approach, can be expensive and relatively inefficient at turning sunlight into electricity. As semiconductor manufacturer Applied Materials chief technology officer Mark Pinto told me last year: "With solar, it's all about cost."

But there are signs of improvement, writes Richard Swanson of SunPower Corp. in this week's Science. Last year, manufacturers made 5 gigawatts of photovoltaic panels. And some of these panels required just under six grams of silicon per watt of power—down from 15 grams at the turn of the century. And that watt of power now costs around $1.40 to produce compared with $2 or more in the 1990s.

Duke Energy wants to put a power plant on your house.

Over the next year, the utility plans to spend $50 million to plop a variety of photovoltaic panels on commercial buildings, the roofs of private homes, and other property in North Carolina.

Once installed, the 10 megawatts worth of solar panels are expected to produce enough alternating-current electricity to power 1,300 homes. But the utility’s main goals for the demonstration project are to gain experience with distributed generation—putting the power plant closer to the customer—and with integrating intermittent, renewable resources like sunshine into the grid.

It was a banner year for wind-energy in 2008, with the U.S. installing enough wind turbines to power two million homes and surpassing Germany to become the country with the most capability of generating power from wind. But can the U.S. remain in the lead in the midst of the recession?

A report released Monday by two wind-power advocacy organizations—the Brussels-based Global Wind Energy Council (GWEC) and Washington, D.C.'s American Wind Energy Association (AWEA)—showed that the U.S. doubled its capacity to create wind power last year. Meanwhile, a clean-energy analyst at investment bank Jeffries & Co., Michael McNamara, told Reuters that the U.S. will become the world's top solar producer this year. (Update [Feb. 6]: McNamara tells us today that the statement attributed to him wasn't quite right. "The U.S. will likely be the biggest producer of solar power in the future," he said.) More than 1,000 megawatts in solar power capacity were installed in the U.S. last year, says Monique Hanis, a spokesperson for the Solar Energy Industries Association (SEIA).

Toyota won't just be adding solar panels to its popular Prius gas-electric hybrid car—like the solar electric conversion kit seen at left—it'll be powering a version of it exclusively via sunshine, according to The Nikkei, Japan's business newspaper. In fact, Toyota will be relying on the solar-electric car to "turn around its struggling business," which resulted in its first operating loss in more than 70 years, the Associated Press reports.

ScientificAmerican.com and other media outlets reported last summer that Toyota was planning to begin selling a Prius with some solar panels as early as May of this year. But the latest reports are that the Japanese automaker is seeking to build a totally solar-driven vehicle.

Maybe they're trying to bring the dead back to life.

A Spanish town alarmed about climate change has installed solar panels on its mausoleums, turning "a place of perpetual rest into one buzzing with renewable energy," the Associated Press reports with mirth.

The 462 panels are mounted on graves in the blue-collar town of Santa Coloma de Gramenet outside of Barcelona. The panels started absorbing energy from the sun to power the local grid last Wednesday, three years after the project began, according to the AP.

So long, Mars Lander.

The NASA robot’s $475-million mission is over, after increasingly cold weather and diminishing sun on Mars got the better of the lander, which relied on sunlight to recharge its solar battery, scientists said yesterday. It hasn’t contacted Earth since November 2.

"We are actually ceasing operations, declaring an end to operations at this point," Barry Goldstein, Phoenix mission project manager at NASA's Jet Propulsion Laboratory in California, told reporters yesterday. "We'll constantly turn on the radio and try to hail Phoenix and see if it's alive, but at this point nobody on the team has any expectations of that happening."

The amount of solar photovoltaics harnessing electricity from sunshine in the U.S. will more than double by 2013, thanks to plans to build 800 megawatts (MW) worth in California. The two vast solar farms—covering more than 12 square miles—will be among the largest ever built in the world and dwarf the current U.S. record holder: Nellis Air Force Base in Nevada with 14 MW. In fact, the total amount of solar photovoltaics connected to the grid in the entire U.S. is just 473 MW at present.

"These landmark agreements signal the arrival of utility-scale PV solar power that may be cost-competitive with solar thermal and wind energy," said Jack Keenan, chief operating officer and senior vice president for utility PG&E, which made the deal, in an announcement yesterday.