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The sun sets over a field of solar energy panels as wind turbines spin nearby, Sept. 4, 2015, near Nauen, Germany. Sean Gallup/Getty Images

Thousands of roofs across Germany are dotted with the metallic glint of solar panels, producing energy that has fueled nearly 7 percent of the country's energy demand since last year. It points to a steady growth since the first introduction of solar power in the early 2000s. The German government has encouraged this widespread use of renewable energy by making the process more accessible and affordable compared to other countries: Installing solar panels on a German home involves little more than filling out basic paperwork and an investment of a few thousand dollars.

“It’s about as easy as renovating your bathroom,” explained Craig Morris, a renewable energy analyst in Germany who has studied renewable energy for two decades.

Despite their overcast climates, European leaders in Germany and France are offering compelling cases for using solar energy, which they have already integrated in their respective power grids and other public installations. Dozens of world leaders met on Monday to discuss climate change at a United Nations summit in Paris and Germany and France, which rank near the top for global energy efficiency, could serve as examples for creative uses of government-subsidized solar energy all over the world.

In the past 10 years, Germany and France have looked to shift from primarily coal and nuclear-fueled energy economies to a mixture of fossil fuel and renewable energy. Unlike other solar leaders in Europe, such as Spain or Italy, the climates of these Western European nations are not the sunniest. Both countries see an average of 1,600 hours of sunshine per year, compared to more than double that number in other warmer countries.

In Germany, a combination of private and public investment spurred a major energy transition toward photovoltaics, or solar panels, composing part of the alternative fuels which provide one-third of the country's energy. The government instituted a feed-in tariff system, which guarantees individuals with solar panels that they can sell energy back to the grid at a price above the retail rate of electricity. “The people encouraged the government to do this, so this is really a case of the government giving people a legal framework that would allow the people to have their investments in renewable energy be profitable,” said Morris.

The concerted effort of the German government to encourage renewable energy is referred to as Energiewende, meaning “energy transition” in German. Energiewende refers to a series of initiatives that began in 2002 which aimed at slowly reducing dependence on fossil fuels by mid-century. Renewable energy, including solar power, is set to account for 33 percent of all domestic power consumption in Germany in 2015, compared to 10 percent in the U.S.

The shift from fossil fuels to renewable energy is not without its costs, however. Critics have pointed out that moving toward alternative fuels, coupled with the loss of cheap Russian gas following the European Union's sanctions on Russia, has pushed electricity prices in Germany steadily up, with the price hovering around 18 cents per kilowatt-hour compared to 7 cents per kilowatt-hour in the U.S. Germany has long had some of the highest electricity costs in the world, however, and proponents of solar power say the long-term effects will save money.

“In the long run, it’s much cheaper to use renewable energy because there are few marginal costs,” said Stefanie Groll of the Boell Foundation, a think tank for green policy reform based out of Germany. She said that the success of solar energy in Germany had been in large part due to the low investment costs, made possible by the government tariff system. The main upfront cost for interested citizens was for installation of the panels. “The wind and the sun -- they don’t charge a bill,” she said.

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Students installed photovoltaic panels in September in Ungersheim, eastern France. AFP/Getty Images

France was slow to embrace these changes and is not as established as Germany when it comes to the implementation of solar energy, but the market is growing in a stable way, according to industry professionals. “It’s still ongoing steadily, and it’s extremely competitive in the sense that the power that’s produced by those solar farms is cheaper than wind ... and it’s way cheaper than any new nuclear facility,” said Marc-Alain Behar of Solaire Direct, a French company that designs, installs and operates photovoltaic farms worldwide.

The thrust in France has come primarily from top-down government initiatives, including subsidies and the installation of solar farms. The legislative body of France passed a law in March that dictates that all new commercial buildings constructed across the nation must be at least partially covered in plants or solar panels.

Around 17.5 percent of all energy in France comes from renewable energy, according to the renewable energy information service, Clean Energy Wire. “It’s relatively modest compared to what’s been going on in other European markets,” said Behar, “but it’s still running quite steadily, as opposed to other markets.” The German solar market in particular has seen fluctuations because of this fixed-tariff model. On especially sunny days, for instance, when solar panels are producing large quantities of energy for the grid, the high supply should lower the cost per kilowatt-hour. Given the fixed-tariff system, however, owners of solar panels are still paid the same price per kilowatt-hour, meaning that the energy is being bought for more than it's worth.

Renewable Energy Production in the United States | FindTheData

Looking to implement solar lessons in France in other parts of the world, French President François Hollande and Indian Prime Minister Narendra Modi launched a global initiative Monday during the climate talks in Paris to bring solar energy to nations worldwide, Reuters reported. The International Solar Alliance sought to establish solar capacities in developing nations, particularly in the tropics.

Across the Atlantic Ocean, the United States has lagged behind Germany and France when it comes to renewable energy: Alternative energy sources account for only about 13 percent of electricity production in the U.S. Subsidies and grid-connectedness vary greatly state by state, with some states like Massachusetts or California enjoying highly developed solar infrastructures while others like South Carolina or Nebraska have very few subsidies. The scope of solar energy in the U.S. is narrow, particularly because solar panels are nearly twice as expensive in the U.S. as they are in Germany, often because of governmental red tape such as expensive permitting procedures.

Solar power in the U.S. would also face additional geographic challenges. “The way the grid is being operated is, of course, more complicated in the U.S.,” said Hendrik Hamann, a researcher in physical sciences for IBM, noting the sheer size of the country compared to Germany and the obstacles concerning storing and transporting solar energy.

“It is only sustainable if we can get the intermittence right,” said Hamann, criticizing the German model for not taking into account possible fluctuations in the market. He noted that the technology to store solar energy was being developed, and that when it is in place, the principle of cheap renewable energy could flourish in the U.S. “If the wind blows, the sun shines, it’s very cheap,” he said.