Mark Bortman of Exact Solar in Yardley, Pa., says having leased solar panels on a roof can add an extra step when selling a house. He says typically a buyer will assume the remainder of the lease, but that requires a credit check and some paperwork Jeff Brady/NPR hide caption

itoggle caption Jeff Brady/NPR

Firefighters douse blazes after a freight train loaded with oil derailed in Lac-Megantic, Quebec, last July. AFP/Getty Images hide caption

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Businessman Tom Wolf talks to U.S. Rep. Allyson Schwartz before the Pennsylvania Democratic Gubernatorial Primary Debate last week in Philadelphia. Michael Perez/AP hide caption

itoggle caption Michael Perez/AP