Are solar panels really saving us any energy? They may seem to have a minimal impact on the envireonment, but it takes energy to mine, process and purify raw materials, and then to manufacture and install the final product.
Market dominating silicon-based panels typically require about two years to return the initial energy investment. But for technology made with perovskites, a type of materials now creating excitement in the solar research community, the energy payback time could be as fast as two to three months, a study by scientists at Northwestern University and the U.S. Department of Energy’s Argonne National Laboratory has found.
That means perovskite modules are more economically and energy efficient than any solar technology commercially available today.
In what is termed a cradle-to-grave life cycle assessment, the research traced products from the mining of its raw materials up to its end in a landfill. They established ecological impacts of making a solar panel, then calculated how long it would take to recover the energy invested.
Corresponding author Fengqi You, assistant professor of chemical and biological engineering at Northwestern, said:
“People see 11 percent efficiency and assume it’s a better product than something that’s 9 percent efficient. But that’s not necessarily true.”
A more complete way to assess solar technology is the energy payback time, which also considers the energy that went into creating the product. Perovskites lag silicon in conversion efficiency, however, they take much less energy to be made into a solar module. So perovskite modules nose ahead with a substantially shorter energy payback time, the shortest, in fact, among existing options for solar power.
Co-author Seth Darling, an Argonne scientist, said:
“Appreciating energy payback times is important if we want to move perovskites from the world of scientific curiosity to the world of relevant commercial technology.”
While this paper featured a thorough environmental assessment of different solar power options, further studies are needed to factor in economic costs. Before putting a perovskite panel on the market, scientists will likely have to replace gold and other unsustainable materials, for both environmental and economic reasons, Darling said.
Jian Gong, Seth B. Darlingb and Fengqi You
Perovskite photovoltaics: life-cycle assessment of energy and environmental impacts
Energy Environ. Sci., 2015,8, 1953-1968 DOI: 10.1039/C5EE00615E
Illustration shows the semi-cubic structure of perovskite materials, and how they would fit into a solar power device. An Argonne-Northwestern study found that perovskite-based solar technology has the quickest energy payback time of all current solar technologies. Credit: Seth Darling