The rapid growth of the solar power industry over the past decade may have exacerbated the global warming situation it was meant to soothe, simply because most of the energy used to manufacture the millions of solar panels came from burning fossil fuels. That irony, according to Stanford University researchers, is coming to an end.

For the first time since the boom started, the electricity generated by all of the world's installed solar photovoltaic (PV) panels last year probably surpassed the amount of energy going into fabricating more modules, according to Michael Dale, a postdoctoral fellow at Stanford's Global Climate & Energy Project (GCEP). With continued technological advances, the global PV industry is poised to pay off its debt of energy as early as 2015, and no later than 2020.

The achievement is largely due to steadily declining energy inputs required to manufacture and install PV systems, according to co-author Sally Benson, GCEP's director. The new study, Benson said, indicates that the amount of energy going into the industry should continue to decline, while the issue remains an important focus of research.

The energy used to produce solar panels is intense. The initial step in producing the silicon at the heart of most panels is to melt silica rock at 3,000 degrees Fahrenheit using electricity, commonly from coal-fired power plants.

As investment and technological development have risen sharply with the number of installed panels, the energetic costs of new PV modules have declined. Thinner silicon wafers are now used to make solar cells, less highly refined materials are now used as the silicon feedstock, and less of the costly material is lost in the manufacturing process. Increasingly, the efficiency of solar cells using thin film technologies that rely on earth-abundant materials such as copper, zinc, tin and carbon have the potential for even greater improvements.

To be considered a success – or simply a positive energy technology – PV panels must ultimately pay back all the energy that went into them, said Dale. The PV industry ran an energy deficit from 2000 to now, consuming 75 percent more energy than it produced just five years ago. The researchers expect this energy debt to be paid off as early as 2015, thanks to declining energy inputs, more durable panels and more efficient conversion of sunlight into electricity.

This story is reprinted from material from Stanford University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.