The United States has supported research into photovoltaics for almost 40 years, recently with a 30 percent investment tax credit. Japan instituted incentives in the 1990s, when photovoltaics cost at least five times as much as residential electricity. In the new millennium, Germany instituted incentives an order of magnitude larger.

Thanks to these efforts, the cost of photovoltaic modules has dropped 40 percent in the last 18 months. Photovoltaic electricity now costs about 15 cents per kilowatt-hour in the best sunlight. That's only twice the cost of wholesale electricity and wind. Costs are expected to continue decreasing, and electricity is worth more during the daytime than at night. That means this technology is finally cheap enough to become a significant element in plans to combat climate change and oil dependence (see "Solar's Great Leap Forward").

The advantages of solar panels are clear. They need no fuel or water, and sunlight is nearly limitless. With 100 times the energy potential of wind, sunlight is sufficient to meet all our energy needs. Photovoltaic panels are also unique for their long, low-cost operating life--now 30 to 40 years, someday perhaps 100. And unlike energy sources that require a constant input of fuel, photovoltaic electricity is almost free once its initial capital cost is recovered.

In 2008, when the U.S. Department of Energy drafted a report looking at the potential for "20 percent wind energy by 2030," the plan called for only 5 percent of the country's energy to come from solar power. Soon, the department will publish a new "solar vision" examining the potential for a plan incorporating 10 percent solar photovoltaics, 10 percent solar thermal, and 10 percent wind by the same year. Meanwhile, further DOE work will look at a goal of deriving 80 percent of our energy from renewable sources in 2050. The European Climate Foundation has released a study with McKinsey showing that renewables could produce 100 percent of European electricity by that date. The reports maintain that reaching these targets will have minimal impact on electricity prices.

The ingredients for a fully green solution to climate change and oil dependence are in our grasp. They include electricity from wind and solar photovoltaics; electric vehicles to get us off gasoline; smart grid and transmission technologies to distribute solar and wind power and to balance supply with demand; and domestic natural gas to fill in the gaps. We don't have to turn Earth's crust into a carbon-sequestration experiment, increase our risks with nuclear, or convert arable land to energy farming. We are on track to deploy safe, renewable technologies to stabilize the price of oil and dial down carbon dioxide emissions as much as we want. Confirming photovoltaics' place among these technologies is a big step in the right direction.

Ken Zweibel is director of the GW Solar Institute at George Washington University.