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Solar FarmEver wonder how much energy has gone into the making of the solar panel industry and what its impact is? Folks at Stanford University are conducting a study called Global Climate & Energy Project (GCEP) to answer this question. For the first time since the solar boom started, the electricity generated by all of the world's installed solar panels last year probably surpassed the amount of energy going into manufacturing more modules, according to Michael Dale, a postdoctoral fellow at Stanford's Global Climate & Energy Project (GCEP).

Despite its fantastically fast growth rate, PV is producing – or just about to start producing – a net energy benefit to society, The required amount of energy to manufacture and install PV systems is steadily declining, 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 their research. To be considered a success – or simply a positive energy technology – PV panels must ultimately pay back all the energy that went into producing 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.

GCEP is focused on developing game-changing energy technologies that can be deployed broadly. If the industry can continue to drive down the energy inputs, we will derive greater benefits from solar power, she said. Developing new technologies with lower energy requirements will allow us to grow the industry at a faster rate. 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. Continued reduction of the energetic costs of producing PV panels can be accomplished in a variety of ways, such as using less materials or switching to producing panels that have much lower energy costs than technologies based on silicon. The study's data covers the various silicon-based technologies as well as newer ones using cadmium telluride and copper indium gallium diselenide as semiconductors.
March 5. Source: WSJ Blog, Apr 02

The PV industry's energetic costs can differ significantly from its financial costs. For example, installation and the components outside the solar cells, like wiring and inverters, as well as soft costs like permitting, account for a third of the financial cost of a system, but only 13 percent of the energy inputs. The industry is focused primarily on reducing financial costs.

Strategic implications: If current rapid growth rates persist, by 2020 about 10 percent of the world's electricity could be produced by PV systems. At today's energy payback rate, producing and installing the new PV modules would consume around 9 percent of global electricity. However, if the energy intensity of PV systems continues to drop at its current learning rate, then by 2020 less than 2 percent of global electricity will be needed to sustain growth of the industry. This may not happen if special attention is not given to reducing energy inputs.

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