The tariff levels are index-linked so they will track the retail price index
The tariffs last 20 years for almost all of the systems, with the exception of solar PV (25 years for systems installed before 1st August 2012) and micro-CHP (10 years).
Yes – once you start at a given tariff, it is guaranteed for the full period shown above and is index linked.
See the details of RPI-related indexation here.
For those who are already registered, tariffs will only change in accordance with the index-linking described above
For future entrants who are not yet registered, tariff levels can change:
In theory, therefore, a PV installation registered on that date would receive tariffs until 31st March 2046!