Solar energy has a reputation as being a clean energy source but hasn't earned it — at least not up until now. That's because in a darkly ironic truth, the power used to manufacture solar panels still comes mainly from electricity generated by fossil fuels. But a new study from Stanford researchers says that the balance may be tipping: all the solar panels online around the world last year produced enough energy to make up for the energy it took to make them, researchers are able to say with more than 50 percent confidence.

There are some important caveats to that future outlook

The future looks even brighter, according to the study, with researchers projecting that the industry will be generating enough power between 2015 and 2020 to offset all of the historic creation costs. There are some important caveats to that future outlook, including that installation and materials costs continue to drop at the rapid rate they have been. Still, the researchers are optimistic solar has finally turned an important corner on its way to becoming a more mainstream energy source. Their full results were published today in the journal Environmental Science and Technology.