Transformers step-down voltage from high levels most efficient for long distance transmission to lower levels for safe distribution to homes and businesses. Having enough transformers for replacement and to support expansion of the electrical grid is essential for ensuring reliability of the power system, but currently there is a shortage of transformers.A study by the National Renewable Energy Laboratory (NREL), a U.S. Department of Energy lab, assessed the factors affecting demand for distribution transformers. To tell us about the findings of this analysis is one of the authors, Killian McKenna, Group Manager of Electrical Engineering for NREL. Killian earned a PhD in Electrical Engineering from University College Dublin