Phoenix, Arizona—From a block away, the house was hardly visible, hidden by a dense stand of native mesquite and palo verde trees and tall clumps of prickly pear cactus. Close up, you could see the concrete block structure, built a half century ago when acres of citrus groves were broken into parcels and replaced by homes.

Turning the site back into desert took some work, Brock Tunnicliff explained, standing outside his house on a typical September morning in the Sonoran desert, temperatures in the mid-80s under a nearly cloudless sky. It also took some courage, because desert landscaping isn't popular in Phoenix. Most people here still prefer a lawn out front and a swimming pool in the back.

For Tunnicliff, who works in natural resource management, adopting native landscape was a logical choice in a desert climate. Bolted to his roof was another rational choice: a solar photovoltaic system that supplies most of his family's electricity needs. He installed the system even though he estimates it will take 12 years to break even on the investment.

"That is the future of energy," he said, pointing to the dark blue panels on his roof.

How far in the future is anyone's guess, however. Four years after Tunnicliff installed the system, a satellite image reveals no other solar panels in his neighborhood. In America's sunniest and driest big city, swimming pools still outnumber solar panels by a thousand to one. In fact, Germany—which receives only half as much sunlight as Arizona—has four times as much solar power installed per capita as the Grand Canyon state. Compared nation-to-nation, Germany's advantage is even more lopsided: This darker, cloudier central European country has 23 times more solar power per capita than the United States.

This is Chapter 6 of a six-part series on Germany's remarkable clean break with coal, oil and nuclear energy. Click to read Chapter 1, Chapter 2, Chapter 3, Chapter 4 and Chapter 5. Or read it all now as a Kindle Single ebook on Amazon for 99 cents.

The primary reason for the renewable energy gulf between the United States and Germany can be summed-up in one word: policy. In 2000, Germany's Renewable Energies Act went into effect, and power generated from the sun, wind, and biomass soared. In 2012, U.S. politicians are still wrangling about whether global warming is a hoax.

Click here to view the slideshow of Germany's switch to renewables.

The absurdity of the U.S. impasse over energy reform was highlighted when the primary author of the Germany law, Hans-Josef Fell, told me what I already had heard from other German leaders—that he was inspired to write the act by what today seems like an unlikely source.

"Your President Jimmy Carter was the first politician to promote an industrial revolution with renewables," Fell said when we met in his Berlin office in April. "I looked to the USA in the 1970s. There was wind power in California and solar power on the White House. I thought, 'Oh, this is wonderful! Why can't we have this in Germany?'"

For a time, the United States led the world in developing renewable energy. At one point the Carter administration's Solar Energy Research Institute (SERI) made the dream of a renewable energy economy so real that it set off alarms in the oil-rich countries of the Middle East.

"The big powers are seriously trying to find alternatives to oil by seeking to draw energy from the sun," Saudi Arabia's oil minister Sheikh Ahmad Zaki Yamani warned his colleagues. "We hope to God they will not succeed quickly because our position in that case will be painful."

Four years later, Carter was defeated by Ronald Reagan. The new administration considered SERI a prime example of what it derided as "solar socialism." The budget of the world's leading solar institute was slashed and before long it was back to (oil) business as usual.

As Fell tells it: "Reagan said, 'Go away with this shit of renewables.' And that was that."

A generation of Germans picked up the renewable torch that the Reagan administration tossed aside and bought up SERI-produced patents at fire-sale prices. The renewable energy revolution didn't end. It moved overseas and was renamed die Energiewende.

Can the American renewable energy revolution be restarted? William Reilly, the director of the U.S. Environmental Protection Agency in the George H.W. Bush administration, thinks so. "We're going to get there, one way or another," he told me during a 2009 interview about his solar-powered home.

Indeed, optimists look at recent energy figures and see evidence that a seismic shift has already begun. Since Reilly and I talked, 3,700 megawatts of solar power have been installed in the United States—nearly twice the amount that existed in 2009. More wind power (4,728 megawatts) was added to the U.S. electrical grid in the first three quarters of 2012 than the total generating capacity from wind just a decade ago (4687 megawatts). All told, over the last four years the percentage of our electricity generated by renewables (not including hydroelectric) has doubled.

Still, energy expert John Farrell warns that it's too early to celebrate an America renewable energy renaissance along the lines of Germany's Energiewende. "The U.S. electric grid is poised for a transformation," Farrell, a senior researcher with the Minnesota-based Institute for Local Self-Reliance, told me, "but we're not there yet."

The numbers support Farrell's caution. Renewable energy's share of the total American electrical pie is pitifully low—just 6 percent. Germany gets a full 25 percent of its electricity from renewable sources—and has its sights set on a goal of 30 percent by 2020 and 80 percent by 2050. Hans-Josef Fell thinks Germany can do even better, reaching 100 percent renewable energy by 2050.

The problem in the United States, John Farrell maintains, is that even as implemented by the relatively renewable-friendly Obama administration, current U.S. federal policy will only take us so far. We may be just now waking up to what the Germans realized more than a dozen years ago. "An energy revolution is only possible with a decentralized structure using proven instruments like the Feed-in Tariff," Farrell said.

If the success of America's energy transformation depends on policy, its potential undoing is found in another single word: politics.

Republicans have seized on the failure of a few government-supported renewable energy projects to damn the entire effort and score easy political points. The GOP head of the Senate Environment and Public Works Committee has called climate change "the greatest hoax ever perpetrated on the American people." Despite polls that consistently show an overwhelming majority of Americans favor more solar power, the GOP-controlled House just as consistently rejects measures that would move in that direction. Meanwhile, oil-rich Saudi Arabia, the country that once was alarmed by Jimmy Carter's plans for increasing renewable energy, recently announced its own $100 billion program to develop solar power—a plan more ambitious than anything currently entertained by the United States.

Still, the experts I talked with in Germany were surprisingly bullish on the chances for a renewed U.S. Energiewende. Jens Kendzia, chief of staff to Green Party leader Bärbel Höhn, believes that the recent progress in the U.S.—small as it is—carries the seeds of an energy transformation. "As you get things done," he said, "it changes the political equation."

That is, after all, how the Energiewende grew and flourished in Germany. When one person in a village installed solar panels and began receiving monthly payments for electricity pumped onto the grid, neighbors took note. Soon panels showed up on more roofs. As Rainer Baake, who helped write the EEG, put it: "Success paves the way for success."

I heard this leitmotif of pragmatic optimism playing wherever I traveled in Germany, and I saw its results in wind turbines spinning out electricity and in solar panels mounted everywhere from the Reichstag roof in Berlin to countless barns and sheds across the German countryside.

Nowhere was this song of hard work and optimism joined more completely with tangible results than at an electrical cooperative in the Black Forest, Schönau Power Supply, that some regard as the Energiewende's birthplace. What began as a parents' movement against nuclear power after the 1986 nuclear disaster at Chernobyl, has grown into one of the largest providers of green energy in Germany. Ursula Sladek was a schoolteacher and mother of five young children when the radiation fell on the village of Schönau. When we talked at the company headquarters in early May, she said she had no idea at the time that she would one day be running an electrical utility with more than 130,000 households and small businesses as customers.

"We just wanted our utility to stop using nuclear power. It seemed very reasonable to me," she said, shaking her head at her own naiveté. "They refused. We wouldn't back down." Then she grinned and wagged her finger, which I took to mean: They should have listened.

In 2011, Sladek was awarded the prestigious Goldman Environmental Prize for her persistent efforts "illustrating how social entrepreneurship and environmental stewardship can come together to tackle...the world's most urgent challenges."

Can the United States learn from these lessons and come together to transform its own energy economy?

As we discussed this question, Ursula turned to Eva Stegen, her communications director, who was more proficient in English, and spoke to her in German.

Stegen laughed before translating.

"She says she once heard a certain sentence by your President Kennedy. She thinks it applies—with a bit of a change. It is: 'Ask not what your energy supplier can do for you, ask what you can do for the Energiewende.'"

Later, sleepless on the long flight west to America, I pulled out my notebook and reread the interview with Sladek. I had dutifully transcribed the Kennedy quote, even though it had seemed light and frivolous at the time, as I'm sure Sladek had meant it to be. But flying home over the dark Atlantic, the words seemed to take on substance. With its Emersonian theme of self-reliance and the "we're-all-in-this-together" affirmation, the quote seemed like a fitting proverb for an Energiewende, American style. Or, at the very least, I thought as I put the notebook away and began to will myself to sleep, it was a start.

Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

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Funding for Clean Break was provided by the Heinrich Böll Foundation, through a Climate Media Fellowship, and by the Rockefeller Brothers Fund.