If your solar PV system is installed and registered for the Feed-in Tariff (FIT) before the end of the year then your FIT rate will increase just a few months later on 1st April 2014 in line with the annual Retail Prices Index (RPI) adjustment. On average over the past 10 years the RPI, which measures changes over time in the cost of goods and services that people buy, has increased by 3.27% per year with only one reduction since its implementation in 1948. The annual RPI FIT adjustment applies to both the generation and export tariff rates.
Solar PV systems installed and registered for the FIT between 1 April and 31 December have their tariff rate adjusted in line with the RPI from 1 April of the next year. However, solar PV systems installed and registered for the FIT between 1 January and 31 March have to wait another 12 months ie until 1 April the year after before their tariff rate is RPI adjusted. So if you have a PV system installed and registered for the FIT before 31 December 2013, your tariff rate could increase by around 3.27% just a few months later.
If you wait until 2014 then your FIT rate will not change for over a year.In addition, as shown in the table below the FIT rates for new PV systems above 50kW are being reduced by 3.5% from 1 January as part of the quarterly reviews of the FIT rates.
This makes the difference in the FIT rates for systems above 50kW installed before and after the end of this year even greater, as demonstrated in the table below. This shows the different FIT rates at 1 April 2014 for PV systems installed before and after the end of the year based on the average RPI inflation over the past decade of 3.27% per year.