Installation estimates

Because of the time delay in registering some installations, the FITs register understates the total capacity installed under the Feed-In Tariffs

It is clear from the reports that some systems are registered some months after they are installed and commissioned. See our original press release.

Installation data and estimates

In addition to the monthly registration data, Ofgem periodically publishes a list of all installations. This shows the date each installation was commissioned and the date it applied for registration. Confusingly it doesn't show the date it was actually registered so it is hard to match to Ofgem's registration report, on which the rest of the data in this section is based.

This graph gives a rough estimate of the possible profile of FITs installations, calculated on the basis summarised below.

The estimated installed volume is shown alongside the monthly registration data, which matches the figures below and here. The timing difference is shown by the line on the graph.

Commissioning, applications and registrations

Analysis of the installations list suggests that the average time between commissioning and applying for registration is about 0.7 months. Comparing this list with the registration reports suggests that it then takes an average of 2.4 months for a system to be registered. This has been as high as 5 months, but recent figures suggest that the overall delay is now less than a month.

... and there are some anomalies. For example the report issued at the end of September 2011 listed applications for 308MW of capacity, yet the online reporting shows that 316MW had been registered (more than had applied!). In the previous month 288MW had applied, but only 232 had been registered.

Basis of the estimate

We have used the installation data from the detailed database for the early months, but augmented this to take into account the possible effect of registration delays. This is based on a purely statistical analysis of the register, using the registration data analysed elsewhere in this section of the website.

In particular we have looked at the timing of registrations in relation to the tariff band period to which they apply, as shown in this graph, which appears in larger size here.