In May 2011 Maryland enacted legislation providing a sales and use tax exemption for sales of electricity from qualifying solar energy and residential wind energy equipment to residential customers. In order to qualify for the exemption, the sale of electricity must be for residential use on a property owned by a net metering eligible customer-generator. Maryland already exempted energy sales under residential or domestic rate schedules on file with the Maryland Public Service Commission (PSC) from the sales and use tax. The law therefore places sales/purchases of electricity under residential solar or wind retail power purchase agreements (PPAs) on a level playing field with customer purchases of electricity from the grid. The exemption took effect July 1, 2011.