Solar panels are an investment -- not only in terms of money, but also energy. It takes energy to mine, process and purify raw materials, and then to manufacture and install the final product.
Silicon-based panels, which dominate the market for solar power, usually need about two years to return this energy investment. But for technology made with perovskites -- a class of materials causing quite a buzz in the solar research community -- the energy payback time could be as quick as two to three months.
By this metric, perovskite modules are better than any solar technology that is commercially available today.
These are the findings of a study by scientists at Northwestern University and the U.S. Department of Energy's Argonne National Laboratory. The study took a broad perspective in evaluating solar technology: In what's called a cradle-to-grave life cycle assessment, scientists traced a product from the mining of its raw materials until its retirement in a landfill. They determined the ecological impacts of making a solar panel and calculated how long it would take to recover the energy invested.