The federal role in promoting renewables has mainly been through tax credits, including production tax credits (PTC) for onshore wind and investment tax credits (ITC) for solar. Under legislation enacted in late 2015, wind projects starting construction in 2016 are eligible for a PTC of $23/MWh for 10 years; the value of the credit steps down for projects started in subsequent years and is phased out for projects begun after 2019. The ITC is 30% for projects started by the end of 2019 and then steps down over the following two years with the residential credit expiring for projects begun after 2021 while the ITC for non-residential systems falls to 10%.