How Did Solar Cells Get So Cheap?

Solar photovoltaic modules have suddenly emerged as one of the cheapest options for bulk electricity supply. In a recent Energy Policy article, Kavlak et al. (2018) describe a methodology for quantifying causes of such cost movements and apply it to photovoltaic modules. Their approach, however, overlooks the "butterfly effect'' of serendipitously interacting people and events, without which photovoltaics likely would still be expensive.