One of the criticisms that's been leveled at the photovoltaic panel industry is that it can take more energy to make the panels than the panels produce over their usable lifespan. But a new study indicates that that may no longer be true, and that the PV panel industry may "pay back" the energy invested in all previous years of panel production as early as 2020.
It takes energy to make PV panels, especially the highly efficient, old-school crystalline silicon kind. Even just creating the silicon crystals requires heating rock or sand to around 3,000°F, and that's not counting the creation of the electronics that connect the silicon wafers to the grid, and the mounting hardware that holds the whole thing together. And then there's the energy used to ship the panels and install them.
As recently as 2010, according to a study by Michael Dale and Sally M. Benson at Stanford University's Global Climate and Energy Project, the amount of energy it took to fabricate and install photovoltaic panels may well still have outstripped the energy end-users gained by using them -- a classic example of a negative Energy Return on Energy Invested (EROEI).
But according to that study, recently published in the journal Environmental Science and Technology, a combination of more efficient manufacturing processes and greater energy productivity at the "user-end" mean that PV manufacturing was probably already energy positive by 2012, using less energy in manufacture than is created when the panels are used. And by 2020, say Dale and Benson, the surplus EROEI from photovoltaic power will likely be large enough to "pay back" the energy deficit accrued in all those earlier years of PV manufacturing.
Dale and Stanford University produced a video to explain the results of the study in laypersons' terms (hat tip to Francie Diep at PopSci for the link):
Which means that at some point soon, the energy investment our global society has put into PV will start to pay off. If it hasn't already.