FITs or Feed In Tariffs
The UK government Department of Energy & Climate Change used powers granted in the Energy Act 2008 introduced FITs. FITs went live on 1st April 2010.
FITs is limited to systems generating less than 50MW, so most home owners can qualify.
Once a system qualifies for FITs there is a guarantee period in which owners get cash back, from what I can find this is 25 years.