The White House official, who asked not to be identified because the installation is in process, wrote in an e-mail the project is "a part of an energy retrofit that will improve the overall energy efficiency of the building."
The retrofit also includes installing updated building controls and variable speed fans, the official added.
Back in 2010, Chu said, "This project reflects President Obama's strong commitment to U.S. leadership in solar energy and the jobs it will create here at home. Deploying solar energy technologies across the country will help America lead the global economy for years to come."
This is not the first time solar panels have graced the White House's roof: President Jimmy Carter had 32 installed in the late 1970s to provide hot water, but President Ronald Reagan removed them in 1986. Then in 2003 President George W. Bush installed a photovoltaic system on a maintenance building and two solar thermal units. The system heated the White House swimming pool.
Two grass-roots campaigns lobbied Obama at the start of his first term to restore solar panels to the roof.
On Thursday, climate activist Bill McKibben, whose group 350.org had organized one of the campaigns to install solar power at the White House, welcomed the news that the installation had begun.
"Better late than never--in truth, no one should ever have taken down the panels Jimmy Carter put on the roof way back in 1979," he said. "But it's very good to know that once again the country's most powerful address will be drawing some of that power from the sun."
In 1979, Carter had predicted the solar water heater on the White House grounds will "either be a curiosity, a museum piece, an example of a road not taken, or it can be just a small part of one of the greatest and most exciting adventures ever undertaken by the American people."
Because of improvements in technology, the price of solar panels has dropped 97 percent since then, and now the solar industry employs more than 120,000 people and generates enough electricity to power more than 1.3 million American homes, according to Rhone Resch of the Solar Energy Industries Association.
The vast majority of the solar panels Carter installed went to Unity College in Maine, where 16 of them were used on the college's cafeteria to heat water and others were placed in storage. One is at Carter's presidential library in Atlanta, Ga., while another is at the Smithsonian's Museum of American History. Three years ago Unity College gave one of the solar panels to the People of China, and Unity students have restored other panels in its energy labs that are now out on loan. Two Swiss filmmakers chronicled the Carter solar panels' fate in the film, "A Road Not Taken."
The Obama administration has already undertaken a number of measures to increase the federal government's energy efficiency and use of renewable energy while cutting greenhouse gas emissions linked to climate change, a plan the president outlined in an executive order he signed in October 2009.
The administration has doubled the number of hybrid cars and truck in the federal fleet, increased the government’s use of renewable energy to 7 percent, cut the federal government's greenhouse gas emissions by 15 percent and committed $2 billion to upgrade federal buildings' energy efficiency through contracting requirements at no up-front cost to taxpayers.
So far these measures have collectively saved 7 million gallons of gas and been equivalent to permanently removing 1.5 million cars from the road, according to the White House.
Obama has set a new goal of having 20 percent of the federal government's energy use come from renewable power by 2020, which includes the Army, Navy, and Air Force deploying a combined 3 gigawatts of renewable energy by the end of the decade.