Contingent degression: corridors, triggers and levels

The contingent element of degression is related to trigger points of capacity deployed under the FITs

The level (or sometimes the timing) of degression can be varied depending on the capacity actually registered for tariffs in the given period.

Two degression approaches have been set; one for solar PV, and one for hydro, wind and AD. The timing and default degression percentages are shown here.

Tariffs for larger-scale wind and hydro are not subject to degression in the same way, but linked to pricing under the RO.

Contingent degression factors

The default degression levels can be adjusted, depending on the actual new capacity installed.

If actual installations are within the default ‘corridor’ the default degression (3.5% per quarter for PV, 5% per annum for others) will apply.

If deployment is below this, a lower degression level applies; and above the default corridor are 2/3 higher triggers where increased degression levels would be used, as shown below.

Degression factors based on deployment

Technology Low corridor Default corridor High 1 corridor High 2 corridor High 3 corridor
AD biogas 2.5% p.a 5% p.a 10% p.a 20% p.a
Hydro 2.5% p.a 5% p.a 10% p.a 20% p.a
Solar PV 0% 3.5% p.q 7% p.q 14% p.q 28% p.q
Wind 2.5% p.a 5% p.a 10% p.a 20% p.a

Contingent ‘degression bands’

The deployment corridors are assessed in various system size bands:

Installed capacity ‘trigger levels’ which define the applicable degression corridor

Technology and band Low corridor Default corridor High 1 corridor High 2 corridor High 3 corridor
AD biogas
<=500kW 0-2.3MW 2.3-4.5MW 4.5-9MW >9MW
>500kW 0-19.2MW 19.2-38.4MW 38.4-76.9MW >76.9MW
Total 0-12.5MW 12.5-25MW 25-50.1MW >50.1MW
Solar PV
<=10kW 0-100MW 100-200MW 200-250MW 250-300MW >300MW
>10kW<=50kW 0-50MW 50-100MW 100-150MW 150-200MW >200MW
>50kW 0-50MW 50-100MW 100-150MW 150-200MW >200MW
<=100kW 0-3.3MW 3.3-6.5MW 65-13.1MW >13.1MW
>100kW n/a 0-36.7MW 36.7-73.4MW >73.4MW

For solar PV, the relevant deployment period is the 3-month period ending three months before the degression applies. For other technologies, it is the calendar year ending three months before the degression rate changes. (See applicable degression dates here).

The actual levels achieved in period which have already completed are shown at the bottom of this page.

Emergency adjustments

In addition to all that the government can impose an emergiency degression at the half year for those technologies which are degressed annually.

It has tried to explain thecircumstances on when and how this would be done, if required.

Anyone remember the time we advised government to “keep it simple”?

Actual deployment levels and related degression %

Th government will publish the relevant deployment figures here, and Ofgem will use them to calculate the revised tariffs, which we show in the blue columns here.

Relevant figures published to date are:

Actual deployment figures and relevant contingent degression

Technology and band Deployment (MW) Corridor Degression rate
Solar PV from 1st May to end Jul 2012 from 1st Nov 2012
<=10kW 163.769 Default 3.5%
>10kW<=50kW 57.091 Default 3.5%
>50kW 13.938 Low 0%