RPI Indexation

Tariffs are indexed to the Retail Price Index

Each year the set level of the generation and export tariffs will be adjusted pro-rata to the retail price index change in the previous calendar year. The Tariff administrators then publish the updated tariff levels.

When does the index-linking apply?

Aaahh! You’ll be sorry you asked. All tariffs used to go up every year in April based on the RPI in the previous calendar year. But now:

After a system is installed and the tariff is set:

The tariff will index with effect from 1st April in the following year. Therefore for a system is installed in January 2013, the tariff was not indexed until April 2014. Why?

Indexing tariffs for future installations:

This got mixed up with the degression mechanism in April 2013, when the non-PV tariffs were increased in line with RPI, but the PV tariffs were not. Why?

Historical index-linking factors

The indices used so far are:

Year beginning RPI Index Cumulative
1st April 2010 [base year] 0%
1st April 2011 4.8% 4.8%
1st April 2012 4.8% 9.8%
1st April 2013 3.1% 13.2%
1st April 2014 2.7% 16.3%
1st April 2015 1.6% 18.2%