Solar power will be even more affordable in 2015 than it is now, a new report from Vice President Joe Biden's office predicts.

The cost of energy from rooftop solar panels is about 21 cents per kilowatt-hour today. Within five years, Biden's office said, it will be just 10 cents per kWh. Utility-scale solar will get less expensive, too, moving from an average of 13 cents per kWh to 6 cents.

Last year's Recovery Act allocated $100 billion for research into energy, transportation and medical science. The fruits of those investments are paying off, Biden said: Funds provided by the public sector are helping stimulate private-sector innovation.

"We're planting the seeds of innovation, but private companies and the nation's top researchers are helping them grow, launching entire new industries, transforming our economy and creating hundreds of thousands of new jobs in the process," the vice president said in releasing the report.

With the help of federal and state subsidies, the solar industry should continue to grow - and if today's pace of innovation continues, solar energy could become an even better investment in the years to come.